/*-------------------------------------------------------------------------
 * drawElements Quality Program OpenGL ES Utilities
 * ------------------------------------------------
 *
 * Copyright 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 *//*!
 * \file
 * \brief Utility functions and structures for texture tests. This code
 * is originated from the modules/glshared/glsTextureTestUtil.hpp and it
 * is tightly coupled with the GLES and Vulkan texture tests!
 *//*--------------------------------------------------------------------*/

#include "gluTextureTestUtil.hpp"

#include "tcuFloat.hpp"
#include "tcuImageCompare.hpp"
#include "tcuTestLog.hpp"
#include "tcuVectorUtil.hpp"

#include "deMath.h"
#include "deStringUtil.hpp"

#include <string>

using std::string;

namespace glu
{

namespace TextureTestUtil
{

enum
{
    MIN_SUBPIXEL_BITS = 4
};

SamplerType getSamplerType(tcu::TextureFormat format)
{
    using tcu::TextureFormat;

    switch (format.type)
    {
    case TextureFormat::SIGNED_INT8:
    case TextureFormat::SIGNED_INT16:
    case TextureFormat::SIGNED_INT32:
        return SAMPLERTYPE_INT;

    case TextureFormat::UNSIGNED_INT8:
    case TextureFormat::UNSIGNED_INT32:
    case TextureFormat::UNSIGNED_INT_1010102_REV:
        return SAMPLERTYPE_UINT;

    // Texture formats used in depth/stencil textures.
    case TextureFormat::UNSIGNED_INT16:
    case TextureFormat::UNSIGNED_INT_24_8:
        return (format.order == TextureFormat::D || format.order == TextureFormat::DS) ? SAMPLERTYPE_FLOAT :
                                                                                         SAMPLERTYPE_UINT;

    default:
        return SAMPLERTYPE_FLOAT;
    }
}

SamplerType getFetchSamplerType(tcu::TextureFormat format)
{
    using tcu::TextureFormat;

    switch (format.type)
    {
    case TextureFormat::SIGNED_INT8:
    case TextureFormat::SIGNED_INT16:
    case TextureFormat::SIGNED_INT32:
        return SAMPLERTYPE_FETCH_INT;

    case TextureFormat::UNSIGNED_INT8:
    case TextureFormat::UNSIGNED_INT32:
    case TextureFormat::UNSIGNED_INT_1010102_REV:
        return SAMPLERTYPE_FETCH_UINT;

    // Texture formats used in depth/stencil textures.
    case TextureFormat::UNSIGNED_INT16:
    case TextureFormat::UNSIGNED_INT_24_8:
        return (format.order == TextureFormat::D || format.order == TextureFormat::DS) ? SAMPLERTYPE_FETCH_FLOAT :
                                                                                         SAMPLERTYPE_FETCH_UINT;

    default:
        return SAMPLERTYPE_FETCH_FLOAT;
    }
}

static tcu::Texture1DView getSubView(const tcu::Texture1DView &view, int baseLevel, int maxLevel,
                                     tcu::ImageViewMinLodParams *minLodParams DE_UNUSED_ATTR)
{
    const int clampedBase = de::clamp(baseLevel, 0, view.getNumLevels() - 1);
    const int clampedMax  = de::clamp(maxLevel, clampedBase, view.getNumLevels() - 1);
    const int numLevels   = clampedMax - clampedBase + 1;
    return tcu::Texture1DView(numLevels, view.getLevels() + clampedBase);
}

static tcu::Texture2DView getSubView(const tcu::Texture2DView &view, int baseLevel, int maxLevel,
                                     tcu::ImageViewMinLodParams *minLodParams = DE_NULL)
{
    const int clampedBase = de::clamp(baseLevel, 0, view.getNumLevels() - 1);
    const int clampedMax  = de::clamp(maxLevel, clampedBase, view.getNumLevels() - 1);
    const int numLevels   = clampedMax - clampedBase + 1;
    return tcu::Texture2DView(numLevels, view.getLevels() + clampedBase, view.isES2(), minLodParams);
}

static tcu::TextureCubeView getSubView(const tcu::TextureCubeView &view, int baseLevel, int maxLevel,
                                       tcu::ImageViewMinLodParams *minLodParams = DE_NULL)
{
    const int clampedBase = de::clamp(baseLevel, 0, view.getNumLevels() - 1);
    const int clampedMax  = de::clamp(maxLevel, clampedBase, view.getNumLevels() - 1);
    const int numLevels   = clampedMax - clampedBase + 1;
    const tcu::ConstPixelBufferAccess *levels[tcu::CUBEFACE_LAST];

    for (int face = 0; face < tcu::CUBEFACE_LAST; face++)
        levels[face] = view.getFaceLevels((tcu::CubeFace)face) + clampedBase;

    return tcu::TextureCubeView(numLevels, levels, false, minLodParams);
}

static tcu::Texture3DView getSubView(const tcu::Texture3DView &view, int baseLevel, int maxLevel,
                                     tcu::ImageViewMinLodParams *minLodParams = DE_NULL)
{
    const int clampedBase = de::clamp(baseLevel, 0, view.getNumLevels() - 1);
    const int clampedMax  = de::clamp(maxLevel, clampedBase, view.getNumLevels() - 1);
    const int numLevels   = clampedMax - clampedBase + 1;
    return tcu::Texture3DView(numLevels, view.getLevels() + clampedBase, false, minLodParams);
}

static tcu::TextureCubeArrayView getSubView(const tcu::TextureCubeArrayView &view, int baseLevel, int maxLevel,
                                            tcu::ImageViewMinLodParams *minLodParams DE_UNUSED_ATTR = DE_NULL)
{
    const int clampedBase = de::clamp(baseLevel, 0, view.getNumLevels() - 1);
    const int clampedMax  = de::clamp(maxLevel, clampedBase, view.getNumLevels() - 1);
    const int numLevels   = clampedMax - clampedBase + 1;
    return tcu::TextureCubeArrayView(numLevels, view.getLevels() + clampedBase);
}

inline float linearInterpolate(float t, float minVal, float maxVal)
{
    return minVal + (maxVal - minVal) * t;
}

inline tcu::Vec4 linearInterpolate(float t, const tcu::Vec4 &a, const tcu::Vec4 &b)
{
    return a + (b - a) * t;
}

inline float bilinearInterpolate(float x, float y, const tcu::Vec4 &quad)
{
    float w00 = (1.0f - x) * (1.0f - y);
    float w01 = (1.0f - x) * y;
    float w10 = x * (1.0f - y);
    float w11 = x * y;
    return quad.x() * w00 + quad.y() * w10 + quad.z() * w01 + quad.w() * w11;
}

float triangleInterpolate(float v0, float v1, float v2, float x, float y)
{
    return v0 + (v2 - v0) * x + (v1 - v0) * y;
}

float triangleInterpolate(const tcu::Vec3 &v, float x, float y)
{
    return triangleInterpolate(v.x(), v.y(), v.z(), x, y);
}

// 1D lookup LOD computation.

float computeLodFromDerivates(LodMode mode, float dudx, float dudy)
{
    float p = 0.0f;
    switch (mode)
    {
    // \note [mika] Min and max bounds equal to exact with 1D textures
    case LODMODE_EXACT:
    case LODMODE_MIN_BOUND:
    case LODMODE_MAX_BOUND:
        p = de::max(deFloatAbs(dudx), deFloatAbs(dudy));
        break;

    default:
        DE_ASSERT(false);
    }

    return deFloatLog2(p);
}

float computeNonProjectedTriLod(LodMode mode, const tcu::IVec2 &dstSize, int32_t srcSize, const tcu::Vec3 &sq)
{
    float dux = (sq.z() - sq.x()) * (float)srcSize;
    float duy = (sq.y() - sq.x()) * (float)srcSize;
    float dx  = (float)dstSize.x();
    float dy  = (float)dstSize.y();

    return computeLodFromDerivates(mode, dux / dx, duy / dy);
}

// 2D lookup LOD computation.

float computeLodFromDerivates(LodMode mode, float dudx, float dvdx, float dudy, float dvdy)
{
    float p = 0.0f;
    switch (mode)
    {
    case LODMODE_EXACT:
        p = de::max(deFloatSqrt(dudx * dudx + dvdx * dvdx), deFloatSqrt(dudy * dudy + dvdy * dvdy));
        break;

    case LODMODE_MIN_BOUND:
    case LODMODE_MAX_BOUND:
    {
        float mu = de::max(deFloatAbs(dudx), deFloatAbs(dudy));
        float mv = de::max(deFloatAbs(dvdx), deFloatAbs(dvdy));

        p = mode == LODMODE_MIN_BOUND ? de::max(mu, mv) : mu + mv;
        break;
    }

    default:
        DE_ASSERT(false);
    }

    return deFloatLog2(p);
}

float computeNonProjectedTriLod(LodMode mode, const tcu::IVec2 &dstSize, const tcu::IVec2 &srcSize, const tcu::Vec3 &sq,
                                const tcu::Vec3 &tq)
{
    float dux = (sq.z() - sq.x()) * (float)srcSize.x();
    float duy = (sq.y() - sq.x()) * (float)srcSize.x();
    float dvx = (tq.z() - tq.x()) * (float)srcSize.y();
    float dvy = (tq.y() - tq.x()) * (float)srcSize.y();
    float dx  = (float)dstSize.x();
    float dy  = (float)dstSize.y();

    return computeLodFromDerivates(mode, dux / dx, dvx / dx, duy / dy, dvy / dy);
}

// 3D lookup LOD computation.

float computeLodFromDerivates(LodMode mode, float dudx, float dvdx, float dwdx, float dudy, float dvdy, float dwdy)
{
    float p = 0.0f;
    switch (mode)
    {
    case LODMODE_EXACT:
        p = de::max(deFloatSqrt(dudx * dudx + dvdx * dvdx + dwdx * dwdx),
                    deFloatSqrt(dudy * dudy + dvdy * dvdy + dwdy * dwdy));
        break;

    case LODMODE_MIN_BOUND:
    case LODMODE_MAX_BOUND:
    {
        float mu = de::max(deFloatAbs(dudx), deFloatAbs(dudy));
        float mv = de::max(deFloatAbs(dvdx), deFloatAbs(dvdy));
        float mw = de::max(deFloatAbs(dwdx), deFloatAbs(dwdy));

        p = mode == LODMODE_MIN_BOUND ? de::max(de::max(mu, mv), mw) : (mu + mv + mw);
        break;
    }

    default:
        DE_ASSERT(false);
    }

    return deFloatLog2(p);
}

float computeNonProjectedTriLod(LodMode mode, const tcu::IVec2 &dstSize, const tcu::IVec3 &srcSize, const tcu::Vec3 &sq,
                                const tcu::Vec3 &tq, const tcu::Vec3 &rq)
{
    float dux = (sq.z() - sq.x()) * (float)srcSize.x();
    float duy = (sq.y() - sq.x()) * (float)srcSize.x();
    float dvx = (tq.z() - tq.x()) * (float)srcSize.y();
    float dvy = (tq.y() - tq.x()) * (float)srcSize.y();
    float dwx = (rq.z() - rq.x()) * (float)srcSize.z();
    float dwy = (rq.y() - rq.x()) * (float)srcSize.z();
    float dx  = (float)dstSize.x();
    float dy  = (float)dstSize.y();

    return computeLodFromDerivates(mode, dux / dx, dvx / dx, dwx / dx, duy / dy, dvy / dy, dwy / dy);
}

static inline float projectedTriInterpolate(const tcu::Vec3 &s, const tcu::Vec3 &w, float nx, float ny)
{
    return (s[0] * (1.0f - nx - ny) / w[0] + s[1] * ny / w[1] + s[2] * nx / w[2]) /
           ((1.0f - nx - ny) / w[0] + ny / w[1] + nx / w[2]);
}

static inline float triDerivateX(const tcu::Vec3 &s, const tcu::Vec3 &w, float wx, float width, float ny)
{
    float d = w[1] * w[2] * (width * (ny - 1.0f) + wx) - w[0] * (w[2] * width * ny + w[1] * wx);
    return (w[0] * w[1] * w[2] * width *
            (w[1] * (s[0] - s[2]) * (ny - 1.0f) + ny * (w[2] * (s[1] - s[0]) + w[0] * (s[2] - s[1])))) /
           (d * d);
}

static inline float triDerivateY(const tcu::Vec3 &s, const tcu::Vec3 &w, float wy, float height, float nx)
{
    float d = w[1] * w[2] * (height * (nx - 1.0f) + wy) - w[0] * (w[1] * height * nx + w[2] * wy);
    return (w[0] * w[1] * w[2] * height *
            (w[2] * (s[0] - s[1]) * (nx - 1.0f) + nx * (w[0] * (s[1] - s[2]) + w[1] * (s[2] - s[0])))) /
           (d * d);
}

// 1D lookup LOD.
static float computeProjectedTriLod(LodMode mode, const tcu::Vec3 &u, const tcu::Vec3 &projection, float wx, float wy,
                                    float width, float height)
{
    // Exact derivatives.
    float dudx = triDerivateX(u, projection, wx, width, wy / height);
    float dudy = triDerivateY(u, projection, wy, height, wx / width);

    return computeLodFromDerivates(mode, dudx, dudy);
}

// 2D lookup LOD.
static float computeProjectedTriLod(LodMode mode, const tcu::Vec3 &u, const tcu::Vec3 &v, const tcu::Vec3 &projection,
                                    float wx, float wy, float width, float height)
{
    // Exact derivatives.
    float dudx = triDerivateX(u, projection, wx, width, wy / height);
    float dvdx = triDerivateX(v, projection, wx, width, wy / height);
    float dudy = triDerivateY(u, projection, wy, height, wx / width);
    float dvdy = triDerivateY(v, projection, wy, height, wx / width);

    return computeLodFromDerivates(mode, dudx, dvdx, dudy, dvdy);
}

// 3D lookup LOD.
static float computeProjectedTriLod(LodMode mode, const tcu::Vec3 &u, const tcu::Vec3 &v, const tcu::Vec3 &w,
                                    const tcu::Vec3 &projection, float wx, float wy, float width, float height)
{
    // Exact derivatives.
    float dudx = triDerivateX(u, projection, wx, width, wy / height);
    float dvdx = triDerivateX(v, projection, wx, width, wy / height);
    float dwdx = triDerivateX(w, projection, wx, width, wy / height);
    float dudy = triDerivateY(u, projection, wy, height, wx / width);
    float dvdy = triDerivateY(v, projection, wy, height, wx / width);
    float dwdy = triDerivateY(w, projection, wy, height, wx / width);

    return computeLodFromDerivates(mode, dudx, dvdx, dwdx, dudy, dvdy, dwdy);
}

static inline tcu::Vec4 execSample(const tcu::Texture1DView &src, const ReferenceParams &params, float s, float lod)
{
    if (params.samplerType == SAMPLERTYPE_SHADOW)
        return tcu::Vec4(src.sampleCompare(params.sampler, params.ref, s, lod), 0.0, 0.0, 1.0f);
    else
        return src.sample(params.sampler, s, lod);
}

static inline tcu::Vec4 execSample(const tcu::Texture2DView &src, const ReferenceParams &params, float s, float t,
                                   float lod)
{
    if (params.samplerType == SAMPLERTYPE_SHADOW)
        return tcu::Vec4(src.sampleCompare(params.sampler, params.ref, s, t, lod), 0.0, 0.0, 1.0f);
    else
        return src.sample(params.sampler, s, t, lod);
}

static inline tcu::Vec4 execSample(const tcu::TextureCubeView &src, const ReferenceParams &params, float s, float t,
                                   float r, float lod)
{
    if (params.samplerType == SAMPLERTYPE_SHADOW)
        return tcu::Vec4(src.sampleCompare(params.sampler, params.ref, s, t, r, lod), 0.0, 0.0, 1.0f);
    else
        return src.sample(params.sampler, s, t, r, lod);
}

static inline tcu::Vec4 execSample(const tcu::Texture2DArrayView &src, const ReferenceParams &params, float s, float t,
                                   float r, float lod)
{
    if (params.samplerType == SAMPLERTYPE_SHADOW)
        return tcu::Vec4(src.sampleCompare(params.sampler, params.ref, s, t, r, lod), 0.0, 0.0, 1.0f);
    else
        return src.sample(params.sampler, s, t, r, lod);
}

static inline tcu::Vec4 execSample(const tcu::TextureCubeArrayView &src, const ReferenceParams &params, float s,
                                   float t, float r, float q, float lod)
{
    if (params.samplerType == SAMPLERTYPE_SHADOW)
        return tcu::Vec4(src.sampleCompare(params.sampler, params.ref, s, t, r, q, lod), 0.0, 0.0, 1.0f);
    else
        return src.sample(params.sampler, s, t, r, q, lod);
}

static inline tcu::Vec4 execSample(const tcu::Texture1DArrayView &src, const ReferenceParams &params, float s, float t,
                                   float lod)
{
    if (params.samplerType == SAMPLERTYPE_SHADOW)
        return tcu::Vec4(src.sampleCompare(params.sampler, params.ref, s, t, lod), 0.0, 0.0, 1.0f);
    else
        return src.sample(params.sampler, s, t, lod);
}

static void sampleTextureNonProjected(const tcu::SurfaceAccess &dst, const tcu::Texture1DView &rawSrc,
                                      const tcu::Vec4 &sq, const ReferenceParams &params)
{
    // Separate combined DS formats
    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::Texture1DView src = getEffectiveTextureView(rawSrc, srcLevelStorage, params.sampler);

    float lodBias = (params.flags & ReferenceParams::USE_BIAS) ? params.bias : 0.0f;

    tcu::IVec2 dstSize = tcu::IVec2(dst.getWidth(), dst.getHeight());
    int srcSize        = src.getWidth();

    // Coordinates and lod per triangle.
    tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    float triLod[2]   = {de::clamp(computeNonProjectedTriLod(params.lodMode, dstSize, srcSize, triS[0]) + lodBias,
                                   params.minLod, params.maxLod),
                         de::clamp(computeNonProjectedTriLod(params.lodMode, dstSize, srcSize, triS[1]) + lodBias,
                                   params.minLod, params.maxLod)};

    for (int y = 0; y < dst.getHeight(); y++)
    {
        for (int x = 0; x < dst.getWidth(); x++)
        {
            float yf = ((float)y + 0.5f) / (float)dst.getHeight();
            float xf = ((float)x + 0.5f) / (float)dst.getWidth();

            int triNdx = xf + yf >= 1.0f ? 1 : 0; // Top left fill rule.
            float triX = triNdx ? 1.0f - xf : xf;
            float triY = triNdx ? 1.0f - yf : yf;

            float s   = triangleInterpolate(triS[triNdx].x(), triS[triNdx].y(), triS[triNdx].z(), triX, triY);
            float lod = triLod[triNdx];

            dst.setPixel(execSample(src, params, s, lod) * params.colorScale + params.colorBias, x, y);
        }
    }
}

template <class PixelAccess>
static void sampleTextureNonProjected(const PixelAccess &dst, const tcu::Texture2DView &rawSrc, const tcu::Vec4 &sq,
                                      const tcu::Vec4 &tq, const ReferenceParams &params)
{
    // Separate combined DS formats
    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    tcu::Texture2DView src = getEffectiveTextureView(rawSrc, srcLevelStorage, params.sampler);

    float lodBias = (params.flags & ReferenceParams::USE_BIAS) ? params.bias : 0.0f;

    tcu::IVec2 dstSize = tcu::IVec2(dst.getWidth(), dst.getHeight());
    tcu::IVec2 srcSize = tcu::IVec2(src.getWidth(), src.getHeight());

    // Coordinates and lod per triangle.
    tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    float triLod[2]   = {
        de::clamp(computeNonProjectedTriLod(params.lodMode, dstSize, srcSize, triS[0], triT[0]) + lodBias,
                    params.minLod, params.maxLod),
        de::clamp(computeNonProjectedTriLod(params.lodMode, dstSize, srcSize, triS[1], triT[1]) + lodBias,
                    params.minLod, params.maxLod)};

    for (int y = 0; y < dst.getHeight(); y++)
    {
        for (int x = 0; x < dst.getWidth(); x++)
        {
            float yf = ((float)y + 0.5f) / (float)dst.getHeight();
            float xf = ((float)x + 0.5f) / (float)dst.getWidth();

            int triNdx = xf + yf >= 1.0f ? 1 : 0; // Top left fill rule.
            float triX = triNdx ? 1.0f - xf : xf;
            float triY = triNdx ? 1.0f - yf : yf;

            float s   = triangleInterpolate(triS[triNdx].x(), triS[triNdx].y(), triS[triNdx].z(), triX, triY);
            float t   = triangleInterpolate(triT[triNdx].x(), triT[triNdx].y(), triT[triNdx].z(), triX, triY);
            float lod = triLod[triNdx];

            if (params.imageViewMinLod != 0.0f && params.samplerType == SAMPLERTYPE_FETCH_FLOAT)
                lod = (float)params.lodTexelFetch;

            if (params.float16TexCoord)
            {
                s = tcu::Float16(s, tcu::ROUND_TO_ZERO).asFloat();
                t = tcu::Float16(t, tcu::ROUND_TO_ZERO).asFloat();
            }

            dst.setPixel(execSample(src, params, s, t, lod) * params.colorScale + params.colorBias, x, y);
        }
    }
}

static void sampleTextureProjected(const tcu::SurfaceAccess &dst, const tcu::Texture1DView &rawSrc, const tcu::Vec4 &sq,
                                   const ReferenceParams &params)
{
    // Separate combined DS formats
    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::Texture1DView src = getEffectiveTextureView(rawSrc, srcLevelStorage, params.sampler);

    float lodBias = (params.flags & ReferenceParams::USE_BIAS) ? params.bias : 0.0f;
    float dstW    = (float)dst.getWidth();
    float dstH    = (float)dst.getHeight();

    tcu::Vec4 uq = sq * (float)src.getWidth();

    tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    tcu::Vec3 triU[2] = {uq.swizzle(0, 1, 2), uq.swizzle(3, 2, 1)};
    tcu::Vec3 triW[2] = {params.w.swizzle(0, 1, 2), params.w.swizzle(3, 2, 1)};

    for (int py = 0; py < dst.getHeight(); py++)
    {
        for (int px = 0; px < dst.getWidth(); px++)
        {
            float wx = (float)px + 0.5f;
            float wy = (float)py + 0.5f;
            float nx = wx / dstW;
            float ny = wy / dstH;

            int triNdx  = nx + ny >= 1.0f ? 1 : 0;
            float triWx = triNdx ? dstW - wx : wx;
            float triWy = triNdx ? dstH - wy : wy;
            float triNx = triNdx ? 1.0f - nx : nx;
            float triNy = triNdx ? 1.0f - ny : ny;

            float s   = projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy);
            float lod = computeProjectedTriLod(params.lodMode, triU[triNdx], triW[triNdx], triWx, triWy,
                                               (float)dst.getWidth(), (float)dst.getHeight()) +
                        lodBias;

            dst.setPixel(execSample(src, params, s, lod) * params.colorScale + params.colorBias, px, py);
        }
    }
}

template <class PixelAccess>
static void sampleTextureProjected(const PixelAccess &dst, const tcu::Texture2DView &rawSrc, const tcu::Vec4 &sq,
                                   const tcu::Vec4 &tq, const ReferenceParams &params)
{
    // Separate combined DS formats
    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::Texture2DView src = getEffectiveTextureView(rawSrc, srcLevelStorage, params.sampler);

    float lodBias = (params.flags & ReferenceParams::USE_BIAS) ? params.bias : 0.0f;
    float dstW    = (float)dst.getWidth();
    float dstH    = (float)dst.getHeight();

    tcu::Vec4 uq = sq * (float)src.getWidth();
    tcu::Vec4 vq = tq * (float)src.getHeight();

    tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    tcu::Vec3 triU[2] = {uq.swizzle(0, 1, 2), uq.swizzle(3, 2, 1)};
    tcu::Vec3 triV[2] = {vq.swizzle(0, 1, 2), vq.swizzle(3, 2, 1)};
    tcu::Vec3 triW[2] = {params.w.swizzle(0, 1, 2), params.w.swizzle(3, 2, 1)};

    for (int py = 0; py < dst.getHeight(); py++)
    {
        for (int px = 0; px < dst.getWidth(); px++)
        {
            float wx = (float)px + 0.5f;
            float wy = (float)py + 0.5f;
            float nx = wx / dstW;
            float ny = wy / dstH;

            int triNdx  = nx + ny >= 1.0f ? 1 : 0;
            float triWx = triNdx ? dstW - wx : wx;
            float triWy = triNdx ? dstH - wy : wy;
            float triNx = triNdx ? 1.0f - nx : nx;
            float triNy = triNdx ? 1.0f - ny : ny;

            float s   = projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy);
            float t   = projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy);
            float lod = computeProjectedTriLod(params.lodMode, triU[triNdx], triV[triNdx], triW[triNdx], triWx, triWy,
                                               (float)dst.getWidth(), (float)dst.getHeight()) +
                        lodBias;

            dst.setPixel(execSample(src, params, s, t, lod) * params.colorScale + params.colorBias, px, py);
        }
    }
}

void sampleTexture(const tcu::PixelBufferAccess &dst, const tcu::Texture2DView &src, const float *texCoord,
                   const ReferenceParams &params)
{
    tcu::ImageViewMinLodParams minLodParams = {
        params.baseLevel, // int baseLevel;
        {
            params.imageViewMinLod,     // float minLod;
            params.imageViewMinLodMode, // ImageViewMinLodMode
        },
        params.samplerType == SAMPLERTYPE_FETCH_FLOAT // bool intTexCoord;
    };

    const tcu::Texture2DView view =
        getSubView(src, params.baseLevel, params.maxLevel, params.imageViewMinLod != 0.0f ? &minLodParams : DE_NULL);
    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[2 + 0], texCoord[4 + 0], texCoord[6 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[2 + 1], texCoord[4 + 1], texCoord[6 + 1]);

    if (params.flags & ReferenceParams::PROJECTED)
        sampleTextureProjected(dst, view, sq, tq, params);
    else
        sampleTextureNonProjected(dst, view, sq, tq, params);
}

void sampleTexture(const tcu::SurfaceAccess &dst, const tcu::Texture2DView &src, const float *texCoord,
                   const ReferenceParams &params)
{
    tcu::ImageViewMinLodParams minLodParams = {
        params.baseLevel, // int baseLevel;
        {
            params.imageViewMinLod,     // float minLod;
            params.imageViewMinLodMode, // ImageViewMinLodMode
        },
        params.samplerType == SAMPLERTYPE_FETCH_FLOAT // bool intTexCoord;
    };

    const tcu::Texture2DView view =
        getSubView(src, params.baseLevel, params.maxLevel, params.imageViewMinLod != 0.0f ? &minLodParams : DE_NULL);
    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[2 + 0], texCoord[4 + 0], texCoord[6 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[2 + 1], texCoord[4 + 1], texCoord[6 + 1]);

    if (params.flags & ReferenceParams::PROJECTED)
        sampleTextureProjected(dst, view, sq, tq, params);
    else
        sampleTextureNonProjected(dst, view, sq, tq, params);
}

void sampleTexture(const tcu::SurfaceAccess &dst, const tcu::Texture1DView &src, const float *texCoord,
                   const ReferenceParams &params)
{
    const tcu::Texture1DView view = getSubView(src, params.baseLevel, params.maxLevel, DE_NULL);
    const tcu::Vec4 sq            = tcu::Vec4(texCoord[0], texCoord[1], texCoord[2], texCoord[3]);

    if (params.flags & ReferenceParams::PROJECTED)
        sampleTextureProjected(dst, view, sq, params);
    else
        sampleTextureNonProjected(dst, view, sq, params);
}

static float computeCubeLodFromDerivates(LodMode lodMode, const tcu::Vec3 &coord, const tcu::Vec3 &coordDx,
                                         const tcu::Vec3 &coordDy, const int faceSize)
{
    const tcu::CubeFace face = tcu::selectCubeFace(coord);
    int maNdx                = 0;
    int sNdx                 = 0;
    int tNdx                 = 0;

    // \note Derivate signs don't matter when computing lod
    switch (face)
    {
    case tcu::CUBEFACE_NEGATIVE_X:
    case tcu::CUBEFACE_POSITIVE_X:
        maNdx = 0;
        sNdx  = 2;
        tNdx  = 1;
        break;
    case tcu::CUBEFACE_NEGATIVE_Y:
    case tcu::CUBEFACE_POSITIVE_Y:
        maNdx = 1;
        sNdx  = 0;
        tNdx  = 2;
        break;
    case tcu::CUBEFACE_NEGATIVE_Z:
    case tcu::CUBEFACE_POSITIVE_Z:
        maNdx = 2;
        sNdx  = 0;
        tNdx  = 1;
        break;
    default:
        DE_ASSERT(false);
    }

    {
        const float sc   = coord[sNdx];
        const float tc   = coord[tNdx];
        const float ma   = de::abs(coord[maNdx]);
        const float scdx = coordDx[sNdx];
        const float tcdx = coordDx[tNdx];
        const float madx = de::abs(coordDx[maNdx]);
        const float scdy = coordDy[sNdx];
        const float tcdy = coordDy[tNdx];
        const float mady = de::abs(coordDy[maNdx]);
        const float dudx = float(faceSize) * 0.5f * (scdx * ma - sc * madx) / (ma * ma);
        const float dvdx = float(faceSize) * 0.5f * (tcdx * ma - tc * madx) / (ma * ma);
        const float dudy = float(faceSize) * 0.5f * (scdy * ma - sc * mady) / (ma * ma);
        const float dvdy = float(faceSize) * 0.5f * (tcdy * ma - tc * mady) / (ma * ma);

        return computeLodFromDerivates(lodMode, dudx, dvdx, dudy, dvdy);
    }
}

static void sampleTextureCube(const tcu::SurfaceAccess &dst, const tcu::TextureCubeView &rawSrc, const tcu::Vec4 &sq,
                              const tcu::Vec4 &tq, const tcu::Vec4 &rq, const ReferenceParams &params)
{
    // Separate combined DS formats
    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::TextureCubeView src = getEffectiveTextureView(rawSrc, srcLevelStorage, params.sampler);

    const tcu::IVec2 dstSize = tcu::IVec2(dst.getWidth(), dst.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const int srcSize        = src.getSize();

    // Coordinates per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {params.w.swizzle(0, 1, 2), params.w.swizzle(3, 2, 1)};

    const float lodBias((params.flags & ReferenceParams::USE_BIAS) ? params.bias : 0.0f);

    for (int py = 0; py < dst.getHeight(); py++)
    {
        for (int px = 0; px < dst.getWidth(); px++)
        {
            const float wx = (float)px + 0.5f;
            const float wy = (float)py + 0.5f;
            const float nx = wx / dstW;
            const float ny = wy / dstH;

            const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
            const float triNx = triNdx ? 1.0f - nx : nx;
            const float triNy = triNdx ? 1.0f - ny : ny;

            const tcu::Vec3 coord(triangleInterpolate(triS[triNdx], triNx, triNy),
                                  triangleInterpolate(triT[triNdx], triNx, triNy),
                                  triangleInterpolate(triR[triNdx], triNx, triNy));
            const tcu::Vec3 coordDx(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                    triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy),
                                    triDerivateX(triR[triNdx], triW[triNdx], wx, dstW, triNy));
            const tcu::Vec3 coordDy(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                    triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx),
                                    triDerivateY(triR[triNdx], triW[triNdx], wy, dstH, triNx));

            const float lod =
                de::clamp(computeCubeLodFromDerivates(params.lodMode, coord, coordDx, coordDy, srcSize) + lodBias,
                          params.minLod, params.maxLod);

            dst.setPixel(execSample(src, params, coord.x(), coord.y(), coord.z(), lod) * params.colorScale +
                             params.colorBias,
                         px, py);
        }
    }
}

void sampleTexture(const tcu::SurfaceAccess &dst, const tcu::TextureCubeView &src, const float *texCoord,
                   const ReferenceParams &params)
{
    tcu::ImageViewMinLodParams minLodParams = {
        params.baseLevel, // int baseLevel;
        {
            params.imageViewMinLod,     // float minLod;
            params.imageViewMinLodMode, // ImageViewMinLodMode
        },
        params.samplerType == SAMPLERTYPE_FETCH_FLOAT // bool intTexCoord;
    };

    const tcu::TextureCubeView view =
        getSubView(src, params.baseLevel, params.maxLevel, params.imageViewMinLod != 0.0f ? &minLodParams : DE_NULL);
    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[3 + 0], texCoord[6 + 0], texCoord[9 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[3 + 1], texCoord[6 + 1], texCoord[9 + 1]);
    const tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[3 + 2], texCoord[6 + 2], texCoord[9 + 2]);

    return sampleTextureCube(dst, view, sq, tq, rq, params);
}

static void sampleTextureNonProjected(const tcu::SurfaceAccess &dst, const tcu::Texture2DArrayView &rawSrc,
                                      const tcu::Vec4 &sq, const tcu::Vec4 &tq, const tcu::Vec4 &rq,
                                      const ReferenceParams &params)
{
    // Separate combined DS formats
    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::Texture2DArrayView src = getEffectiveTextureView(rawSrc, srcLevelStorage, params.sampler);

    float lodBias = (params.flags & ReferenceParams::USE_BIAS) ? params.bias : 0.0f;

    tcu::IVec2 dstSize = tcu::IVec2(dst.getWidth(), dst.getHeight());
    tcu::IVec2 srcSize = tcu::IVec2(src.getWidth(), src.getHeight());

    // Coordinates and lod per triangle.
    tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    float triLod[2]   = {
        de::clamp(computeNonProjectedTriLod(params.lodMode, dstSize, srcSize, triS[0], triT[0]) + lodBias,
                    params.minLod, params.maxLod),
        de::clamp(computeNonProjectedTriLod(params.lodMode, dstSize, srcSize, triS[1], triT[1]) + lodBias,
                    params.minLod, params.maxLod)};

    for (int y = 0; y < dst.getHeight(); y++)
    {
        for (int x = 0; x < dst.getWidth(); x++)
        {
            float yf = ((float)y + 0.5f) / (float)dst.getHeight();
            float xf = ((float)x + 0.5f) / (float)dst.getWidth();

            int triNdx = xf + yf >= 1.0f ? 1 : 0; // Top left fill rule.
            float triX = triNdx ? 1.0f - xf : xf;
            float triY = triNdx ? 1.0f - yf : yf;

            float s   = triangleInterpolate(triS[triNdx].x(), triS[triNdx].y(), triS[triNdx].z(), triX, triY);
            float t   = triangleInterpolate(triT[triNdx].x(), triT[triNdx].y(), triT[triNdx].z(), triX, triY);
            float r   = triangleInterpolate(triR[triNdx].x(), triR[triNdx].y(), triR[triNdx].z(), triX, triY);
            float lod = triLod[triNdx];

            dst.setPixel(execSample(src, params, s, t, r, lod) * params.colorScale + params.colorBias, x, y);
        }
    }
}

void sampleTexture(const tcu::SurfaceAccess &dst, const tcu::Texture2DArrayView &src, const float *texCoord,
                   const ReferenceParams &params)
{
    tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[3 + 0], texCoord[6 + 0], texCoord[9 + 0]);
    tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[3 + 1], texCoord[6 + 1], texCoord[9 + 1]);
    tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[3 + 2], texCoord[6 + 2], texCoord[9 + 2]);

    DE_ASSERT(!(params.flags & ReferenceParams::PROJECTED)); // \todo [2012-02-17 pyry] Support projected lookups.
    sampleTextureNonProjected(dst, src, sq, tq, rq, params);
}

static void sampleTextureNonProjected(const tcu::SurfaceAccess &dst, const tcu::Texture1DArrayView &rawSrc,
                                      const tcu::Vec4 &sq, const tcu::Vec4 &tq, const ReferenceParams &params)
{
    // Separate combined DS formats
    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::Texture1DArrayView src = getEffectiveTextureView(rawSrc, srcLevelStorage, params.sampler);

    float lodBias = (params.flags & ReferenceParams::USE_BIAS) ? params.bias : 0.0f;

    tcu::IVec2 dstSize = tcu::IVec2(dst.getWidth(), dst.getHeight());
    int32_t srcSize    = src.getWidth();

    // Coordinates and lod per triangle.
    tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    float triLod[2]   = {computeNonProjectedTriLod(params.lodMode, dstSize, srcSize, triS[0]) + lodBias,
                         computeNonProjectedTriLod(params.lodMode, dstSize, srcSize, triS[1]) + lodBias};

    for (int y = 0; y < dst.getHeight(); y++)
    {
        for (int x = 0; x < dst.getWidth(); x++)
        {
            float yf = ((float)y + 0.5f) / (float)dst.getHeight();
            float xf = ((float)x + 0.5f) / (float)dst.getWidth();

            int triNdx = xf + yf >= 1.0f ? 1 : 0; // Top left fill rule.
            float triX = triNdx ? 1.0f - xf : xf;
            float triY = triNdx ? 1.0f - yf : yf;

            float s   = triangleInterpolate(triS[triNdx].x(), triS[triNdx].y(), triS[triNdx].z(), triX, triY);
            float t   = triangleInterpolate(triT[triNdx].x(), triT[triNdx].y(), triT[triNdx].z(), triX, triY);
            float lod = triLod[triNdx];

            dst.setPixel(execSample(src, params, s, t, lod) * params.colorScale + params.colorBias, x, y);
        }
    }
}

void sampleTexture(const tcu::SurfaceAccess &dst, const tcu::Texture1DArrayView &src, const float *texCoord,
                   const ReferenceParams &params)
{
    tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[2 + 0], texCoord[4 + 0], texCoord[6 + 0]);
    tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[2 + 1], texCoord[4 + 1], texCoord[6 + 1]);

    DE_ASSERT(!(params.flags & ReferenceParams::PROJECTED)); // \todo [2014-06-09 mika] Support projected lookups.
    sampleTextureNonProjected(dst, src, sq, tq, params);
}

static void sampleTextureNonProjected(const tcu::SurfaceAccess &dst, const tcu::Texture3DView &rawSrc,
                                      const tcu::Vec4 &sq, const tcu::Vec4 &tq, const tcu::Vec4 &rq,
                                      const ReferenceParams &params)
{
    // Separate combined DS formats
    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::Texture3DView src = getEffectiveTextureView(rawSrc, srcLevelStorage, params.sampler);

    float lodBias = (params.flags & ReferenceParams::USE_BIAS) ? params.bias : 0.0f;

    tcu::IVec2 dstSize = tcu::IVec2(dst.getWidth(), dst.getHeight());
    tcu::IVec3 srcSize = tcu::IVec3(src.getWidth(), src.getHeight(), src.getDepth());

    // Coordinates and lod per triangle.
    tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    float triLod[2]   = {
        de::clamp(computeNonProjectedTriLod(params.lodMode, dstSize, srcSize, triS[0], triT[0], triR[0]) + lodBias,
                    params.minLod, params.maxLod),
        de::clamp(computeNonProjectedTriLod(params.lodMode, dstSize, srcSize, triS[1], triT[1], triR[1]) + lodBias,
                    params.minLod, params.maxLod)};

    for (int y = 0; y < dst.getHeight(); y++)
    {
        for (int x = 0; x < dst.getWidth(); x++)
        {
            float yf = ((float)y + 0.5f) / (float)dst.getHeight();
            float xf = ((float)x + 0.5f) / (float)dst.getWidth();

            int triNdx = xf + yf >= 1.0f ? 1 : 0; // Top left fill rule.
            float triX = triNdx ? 1.0f - xf : xf;
            float triY = triNdx ? 1.0f - yf : yf;

            float s   = triangleInterpolate(triS[triNdx].x(), triS[triNdx].y(), triS[triNdx].z(), triX, triY);
            float t   = triangleInterpolate(triT[triNdx].x(), triT[triNdx].y(), triT[triNdx].z(), triX, triY);
            float r   = triangleInterpolate(triR[triNdx].x(), triR[triNdx].y(), triR[triNdx].z(), triX, triY);
            float lod = triLod[triNdx];

            if (params.imageViewMinLod != 0.0f && params.samplerType == SAMPLERTYPE_FETCH_FLOAT)
                lod = (float)params.lodTexelFetch;

            dst.setPixel(src.sample(params.sampler, s, t, r, lod) * params.colorScale + params.colorBias, x, y);
        }
    }
}

static void sampleTextureProjected(const tcu::SurfaceAccess &dst, const tcu::Texture3DView &rawSrc, const tcu::Vec4 &sq,
                                   const tcu::Vec4 &tq, const tcu::Vec4 &rq, const ReferenceParams &params)
{
    // Separate combined DS formats
    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::Texture3DView src = getEffectiveTextureView(rawSrc, srcLevelStorage, params.sampler);

    float lodBias = (params.flags & ReferenceParams::USE_BIAS) ? params.bias : 0.0f;
    float dstW    = (float)dst.getWidth();
    float dstH    = (float)dst.getHeight();

    tcu::Vec4 uq = sq * (float)src.getWidth();
    tcu::Vec4 vq = tq * (float)src.getHeight();
    tcu::Vec4 wq = rq * (float)src.getDepth();

    tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    tcu::Vec3 triU[2] = {uq.swizzle(0, 1, 2), uq.swizzle(3, 2, 1)};
    tcu::Vec3 triV[2] = {vq.swizzle(0, 1, 2), vq.swizzle(3, 2, 1)};
    tcu::Vec3 triW[2] = {wq.swizzle(0, 1, 2), wq.swizzle(3, 2, 1)};
    tcu::Vec3 triP[2] = {params.w.swizzle(0, 1, 2), params.w.swizzle(3, 2, 1)};

    for (int py = 0; py < dst.getHeight(); py++)
    {
        for (int px = 0; px < dst.getWidth(); px++)
        {
            float wx = (float)px + 0.5f;
            float wy = (float)py + 0.5f;
            float nx = wx / dstW;
            float ny = wy / dstH;

            int triNdx  = nx + ny >= 1.0f ? 1 : 0;
            float triWx = triNdx ? dstW - wx : wx;
            float triWy = triNdx ? dstH - wy : wy;
            float triNx = triNdx ? 1.0f - nx : nx;
            float triNy = triNdx ? 1.0f - ny : ny;

            float s   = projectedTriInterpolate(triS[triNdx], triP[triNdx], triNx, triNy);
            float t   = projectedTriInterpolate(triT[triNdx], triP[triNdx], triNx, triNy);
            float r   = projectedTriInterpolate(triR[triNdx], triP[triNdx], triNx, triNy);
            float lod = computeProjectedTriLod(params.lodMode, triU[triNdx], triV[triNdx], triW[triNdx], triP[triNdx],
                                               triWx, triWy, (float)dst.getWidth(), (float)dst.getHeight()) +
                        lodBias;

            dst.setPixel(src.sample(params.sampler, s, t, r, lod) * params.colorScale + params.colorBias, px, py);
        }
    }
}

void sampleTexture(const tcu::SurfaceAccess &dst, const tcu::Texture3DView &src, const float *texCoord,
                   const ReferenceParams &params)
{
    tcu::ImageViewMinLodParams minLodParams = {
        params.baseLevel, // int baseLevel;
        {
            params.imageViewMinLod,     // float minLod;
            params.imageViewMinLodMode, // ImageViewMinLodMode
        },
        params.samplerType == SAMPLERTYPE_FETCH_FLOAT // bool intTexCoord;
    };

    const tcu::Texture3DView view =
        getSubView(src, params.baseLevel, params.maxLevel, params.imageViewMinLod != 0.0f ? &minLodParams : DE_NULL);
    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[3 + 0], texCoord[6 + 0], texCoord[9 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[3 + 1], texCoord[6 + 1], texCoord[9 + 1]);
    const tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[3 + 2], texCoord[6 + 2], texCoord[9 + 2]);

    if (params.flags & ReferenceParams::PROJECTED)
        sampleTextureProjected(dst, view, sq, tq, rq, params);
    else
        sampleTextureNonProjected(dst, view, sq, tq, rq, params);
}

static void sampleTextureCubeArray(const tcu::SurfaceAccess &dst, const tcu::TextureCubeArrayView &rawSrc,
                                   const tcu::Vec4 &sq, const tcu::Vec4 &tq, const tcu::Vec4 &rq, const tcu::Vec4 &qq,
                                   const ReferenceParams &params)
{
    // Separate combined DS formats
    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::TextureCubeArrayView src = getEffectiveTextureView(rawSrc, srcLevelStorage, params.sampler);

    const float dstW = (float)dst.getWidth();
    const float dstH = (float)dst.getHeight();

    // Coordinates per triangle.
    tcu::Vec3 triS[2]       = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    tcu::Vec3 triT[2]       = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    tcu::Vec3 triR[2]       = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    tcu::Vec3 triQ[2]       = {qq.swizzle(0, 1, 2), qq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {params.w.swizzle(0, 1, 2), params.w.swizzle(3, 2, 1)};

    const float lodBias = (params.flags & ReferenceParams::USE_BIAS) ? params.bias : 0.0f;

    for (int py = 0; py < dst.getHeight(); py++)
    {
        for (int px = 0; px < dst.getWidth(); px++)
        {
            const float wx = (float)px + 0.5f;
            const float wy = (float)py + 0.5f;
            const float nx = wx / dstW;
            const float ny = wy / dstH;

            const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
            const float triNx = triNdx ? 1.0f - nx : nx;
            const float triNy = triNdx ? 1.0f - ny : ny;

            const tcu::Vec3 coord(triangleInterpolate(triS[triNdx], triNx, triNy),
                                  triangleInterpolate(triT[triNdx], triNx, triNy),
                                  triangleInterpolate(triR[triNdx], triNx, triNy));

            const float coordQ = triangleInterpolate(triQ[triNdx], triNx, triNy);

            const tcu::Vec3 coordDx(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                    triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy),
                                    triDerivateX(triR[triNdx], triW[triNdx], wx, dstW, triNy));
            const tcu::Vec3 coordDy(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                    triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx),
                                    triDerivateY(triR[triNdx], triW[triNdx], wy, dstH, triNx));

            const float lod =
                de::clamp(computeCubeLodFromDerivates(params.lodMode, coord, coordDx, coordDy, src.getSize()) + lodBias,
                          params.minLod, params.maxLod);

            dst.setPixel(execSample(src, params, coord.x(), coord.y(), coord.z(), coordQ, lod) * params.colorScale +
                             params.colorBias,
                         px, py);
        }
    }
}

void sampleTexture(const tcu::SurfaceAccess &dst, const tcu::TextureCubeArrayView &src, const float *texCoord,
                   const ReferenceParams &params)
{
    tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[4 + 0], texCoord[8 + 0], texCoord[12 + 0]);
    tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[4 + 1], texCoord[8 + 1], texCoord[12 + 1]);
    tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[4 + 2], texCoord[8 + 2], texCoord[12 + 2]);
    tcu::Vec4 qq = tcu::Vec4(texCoord[0 + 3], texCoord[4 + 3], texCoord[8 + 3], texCoord[12 + 3]);

    sampleTextureCubeArray(dst, src, sq, tq, rq, qq, params);
}

void fetchTexture(const tcu::SurfaceAccess &dst, const tcu::ConstPixelBufferAccess &src, const float *texCoord,
                  const tcu::Vec4 &colorScale, const tcu::Vec4 &colorBias)
{
    const tcu::Vec4 sq      = tcu::Vec4(texCoord[0], texCoord[1], texCoord[2], texCoord[3]);
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};

    for (int y = 0; y < dst.getHeight(); y++)
    {
        for (int x = 0; x < dst.getWidth(); x++)
        {
            const float yf = ((float)y + 0.5f) / (float)dst.getHeight();
            const float xf = ((float)x + 0.5f) / (float)dst.getWidth();

            const int triNdx = xf + yf >= 1.0f ? 1 : 0; // Top left fill rule.
            const float triX = triNdx ? 1.0f - xf : xf;
            const float triY = triNdx ? 1.0f - yf : yf;

            const float s = triangleInterpolate(triS[triNdx].x(), triS[triNdx].y(), triS[triNdx].z(), triX, triY);

            dst.setPixel(src.getPixel((int)s, 0) * colorScale + colorBias, x, y);
        }
    }
}

bool compareImages(tcu::TestLog &log, const tcu::Surface &reference, const tcu::Surface &rendered, tcu::RGBA threshold)
{
    return tcu::pixelThresholdCompare(log, "Result", "Image comparison result", reference, rendered, threshold,
                                      tcu::COMPARE_LOG_RESULT);
}

bool compareImages(tcu::TestLog &log, const char *name, const char *desc, const tcu::Surface &reference,
                   const tcu::Surface &rendered, tcu::RGBA threshold)
{
    return tcu::pixelThresholdCompare(log, name, desc, reference, rendered, threshold, tcu::COMPARE_LOG_RESULT);
}

int measureAccuracy(tcu::TestLog &log, const tcu::Surface &reference, const tcu::Surface &rendered, int bestScoreDiff,
                    int worstScoreDiff)
{
    return tcu::measurePixelDiffAccuracy(log, "Result", "Image comparison result", reference, rendered, bestScoreDiff,
                                         worstScoreDiff, tcu::COMPARE_LOG_EVERYTHING);
}

inline int rangeDiff(int x, int a, int b)
{
    if (x < a)
        return a - x;
    else if (x > b)
        return x - b;
    else
        return 0;
}

inline tcu::RGBA rangeDiff(tcu::RGBA p, tcu::RGBA a, tcu::RGBA b)
{
    int rMin = de::min(a.getRed(), b.getRed());
    int rMax = de::max(a.getRed(), b.getRed());
    int gMin = de::min(a.getGreen(), b.getGreen());
    int gMax = de::max(a.getGreen(), b.getGreen());
    int bMin = de::min(a.getBlue(), b.getBlue());
    int bMax = de::max(a.getBlue(), b.getBlue());
    int aMin = de::min(a.getAlpha(), b.getAlpha());
    int aMax = de::max(a.getAlpha(), b.getAlpha());

    return tcu::RGBA(rangeDiff(p.getRed(), rMin, rMax), rangeDiff(p.getGreen(), gMin, gMax),
                     rangeDiff(p.getBlue(), bMin, bMax), rangeDiff(p.getAlpha(), aMin, aMax));
}

inline bool rangeCompare(tcu::RGBA p, tcu::RGBA a, tcu::RGBA b, tcu::RGBA threshold)
{
    tcu::RGBA diff = rangeDiff(p, a, b);
    return diff.getRed() <= threshold.getRed() && diff.getGreen() <= threshold.getGreen() &&
           diff.getBlue() <= threshold.getBlue() && diff.getAlpha() <= threshold.getAlpha();
}

void computeQuadTexCoord1D(std::vector<float> &dst, float left, float right)
{
    dst.resize(4);

    dst[0] = left;
    dst[1] = left;
    dst[2] = right;
    dst[3] = right;
}

void computeQuadTexCoord1DArray(std::vector<float> &dst, int layerNdx, float left, float right)
{
    dst.resize(4 * 2);

    dst[0] = left;
    dst[1] = (float)layerNdx;
    dst[2] = left;
    dst[3] = (float)layerNdx;
    dst[4] = right;
    dst[5] = (float)layerNdx;
    dst[6] = right;
    dst[7] = (float)layerNdx;
}

void computeQuadTexCoord2D(std::vector<float> &dst, const tcu::Vec2 &bottomLeft, const tcu::Vec2 &topRight)
{
    dst.resize(4 * 2);

    dst[0] = bottomLeft.x();
    dst[1] = bottomLeft.y();
    dst[2] = bottomLeft.x();
    dst[3] = topRight.y();
    dst[4] = topRight.x();
    dst[5] = bottomLeft.y();
    dst[6] = topRight.x();
    dst[7] = topRight.y();
}

void computeQuadTexCoord2DArray(std::vector<float> &dst, int layerNdx, const tcu::Vec2 &bottomLeft,
                                const tcu::Vec2 &topRight)
{
    dst.resize(4 * 3);

    dst[0]  = bottomLeft.x();
    dst[1]  = bottomLeft.y();
    dst[2]  = (float)layerNdx;
    dst[3]  = bottomLeft.x();
    dst[4]  = topRight.y();
    dst[5]  = (float)layerNdx;
    dst[6]  = topRight.x();
    dst[7]  = bottomLeft.y();
    dst[8]  = (float)layerNdx;
    dst[9]  = topRight.x();
    dst[10] = topRight.y();
    dst[11] = (float)layerNdx;
}

void computeQuadTexCoord3D(std::vector<float> &dst, const tcu::Vec3 &p0, const tcu::Vec3 &p1, const tcu::IVec3 &dirSwz)
{
    tcu::Vec3 f0 = tcu::Vec3(0.0f, 0.0f, 0.0f).swizzle(dirSwz[0], dirSwz[1], dirSwz[2]);
    tcu::Vec3 f1 = tcu::Vec3(0.0f, 1.0f, 0.0f).swizzle(dirSwz[0], dirSwz[1], dirSwz[2]);
    tcu::Vec3 f2 = tcu::Vec3(1.0f, 0.0f, 0.0f).swizzle(dirSwz[0], dirSwz[1], dirSwz[2]);
    tcu::Vec3 f3 = tcu::Vec3(1.0f, 1.0f, 0.0f).swizzle(dirSwz[0], dirSwz[1], dirSwz[2]);

    tcu::Vec3 v0 = p0 + (p1 - p0) * f0;
    tcu::Vec3 v1 = p0 + (p1 - p0) * f1;
    tcu::Vec3 v2 = p0 + (p1 - p0) * f2;
    tcu::Vec3 v3 = p0 + (p1 - p0) * f3;

    dst.resize(4 * 3);

    dst[0]  = v0.x();
    dst[1]  = v0.y();
    dst[2]  = v0.z();
    dst[3]  = v1.x();
    dst[4]  = v1.y();
    dst[5]  = v1.z();
    dst[6]  = v2.x();
    dst[7]  = v2.y();
    dst[8]  = v2.z();
    dst[9]  = v3.x();
    dst[10] = v3.y();
    dst[11] = v3.z();
}

void computeQuadTexCoordCube(std::vector<float> &dst, tcu::CubeFace face)
{
    static const float texCoordNegX[] = {-1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f,
                                         -1.0f, 1.0f, 1.0f,  -1.0f, -1.0f, 1.0f};
    static const float texCoordPosX[] = {+1.0f, 1.0f, 1.0f,  +1.0f, -1.0f, 1.0f,
                                         +1.0f, 1.0f, -1.0f, +1.0f, -1.0f, -1.0f};
    static const float texCoordNegY[] = {-1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f,
                                         1.0f,  -1.0f, 1.0f, 1.0f,  -1.0f, -1.0f};
    static const float texCoordPosY[] = {-1.0f, +1.0f, -1.0f, -1.0f, +1.0f, 1.0f,
                                         1.0f,  +1.0f, -1.0f, 1.0f,  +1.0f, 1.0f};
    static const float texCoordNegZ[] = {1.0f,  1.0f, -1.0f, 1.0f,  -1.0f, -1.0f,
                                         -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f};
    static const float texCoordPosZ[] = {-1.0f, 1.0f, +1.0f, -1.0f, -1.0f, +1.0f,
                                         1.0f,  1.0f, +1.0f, 1.0f,  -1.0f, +1.0f};

    const float *texCoord = DE_NULL;
    int texCoordSize      = DE_LENGTH_OF_ARRAY(texCoordNegX);

    switch (face)
    {
    case tcu::CUBEFACE_NEGATIVE_X:
        texCoord = texCoordNegX;
        break;
    case tcu::CUBEFACE_POSITIVE_X:
        texCoord = texCoordPosX;
        break;
    case tcu::CUBEFACE_NEGATIVE_Y:
        texCoord = texCoordNegY;
        break;
    case tcu::CUBEFACE_POSITIVE_Y:
        texCoord = texCoordPosY;
        break;
    case tcu::CUBEFACE_NEGATIVE_Z:
        texCoord = texCoordNegZ;
        break;
    case tcu::CUBEFACE_POSITIVE_Z:
        texCoord = texCoordPosZ;
        break;
    default:
        DE_ASSERT(false);
        return;
    }

    dst.resize(texCoordSize);
    std::copy(texCoord, texCoord + texCoordSize, dst.begin());
}

void computeQuadTexCoordCube(std::vector<float> &dst, tcu::CubeFace face, const tcu::Vec2 &bottomLeft,
                             const tcu::Vec2 &topRight)
{
    int sRow    = 0;
    int tRow    = 0;
    int mRow    = 0;
    float sSign = 1.0f;
    float tSign = 1.0f;
    float mSign = 1.0f;

    switch (face)
    {
    case tcu::CUBEFACE_NEGATIVE_X:
        mRow  = 0;
        sRow  = 2;
        tRow  = 1;
        mSign = -1.0f;
        tSign = -1.0f;
        break;
    case tcu::CUBEFACE_POSITIVE_X:
        mRow  = 0;
        sRow  = 2;
        tRow  = 1;
        sSign = -1.0f;
        tSign = -1.0f;
        break;
    case tcu::CUBEFACE_NEGATIVE_Y:
        mRow  = 1;
        sRow  = 0;
        tRow  = 2;
        mSign = -1.0f;
        tSign = -1.0f;
        break;
    case tcu::CUBEFACE_POSITIVE_Y:
        mRow = 1;
        sRow = 0;
        tRow = 2;
        break;
    case tcu::CUBEFACE_NEGATIVE_Z:
        mRow  = 2;
        sRow  = 0;
        tRow  = 1;
        mSign = -1.0f;
        sSign = -1.0f;
        tSign = -1.0f;
        break;
    case tcu::CUBEFACE_POSITIVE_Z:
        mRow  = 2;
        sRow  = 0;
        tRow  = 1;
        tSign = -1.0f;
        break;
    default:
        DE_ASSERT(false);
        return;
    }

    dst.resize(3 * 4);

    dst[0 + mRow] = mSign;
    dst[3 + mRow] = mSign;
    dst[6 + mRow] = mSign;
    dst[9 + mRow] = mSign;

    dst[0 + sRow] = sSign * bottomLeft.x();
    dst[3 + sRow] = sSign * bottomLeft.x();
    dst[6 + sRow] = sSign * topRight.x();
    dst[9 + sRow] = sSign * topRight.x();

    dst[0 + tRow] = tSign * bottomLeft.y();
    dst[3 + tRow] = tSign * topRight.y();
    dst[6 + tRow] = tSign * bottomLeft.y();
    dst[9 + tRow] = tSign * topRight.y();
}

void computeQuadTexCoordCubeArray(std::vector<float> &dst, tcu::CubeFace face, const tcu::Vec2 &bottomLeft,
                                  const tcu::Vec2 &topRight, const tcu::Vec2 &layerRange)
{
    int sRow       = 0;
    int tRow       = 0;
    int mRow       = 0;
    const int qRow = 3;
    float sSign    = 1.0f;
    float tSign    = 1.0f;
    float mSign    = 1.0f;
    const float l0 = layerRange.x();
    const float l1 = layerRange.y();

    switch (face)
    {
    case tcu::CUBEFACE_NEGATIVE_X:
        mRow  = 0;
        sRow  = 2;
        tRow  = 1;
        mSign = -1.0f;
        tSign = -1.0f;
        break;
    case tcu::CUBEFACE_POSITIVE_X:
        mRow  = 0;
        sRow  = 2;
        tRow  = 1;
        sSign = -1.0f;
        tSign = -1.0f;
        break;
    case tcu::CUBEFACE_NEGATIVE_Y:
        mRow  = 1;
        sRow  = 0;
        tRow  = 2;
        mSign = -1.0f;
        tSign = -1.0f;
        break;
    case tcu::CUBEFACE_POSITIVE_Y:
        mRow = 1;
        sRow = 0;
        tRow = 2;
        break;
    case tcu::CUBEFACE_NEGATIVE_Z:
        mRow  = 2;
        sRow  = 0;
        tRow  = 1;
        mSign = -1.0f;
        sSign = -1.0f;
        tSign = -1.0f;
        break;
    case tcu::CUBEFACE_POSITIVE_Z:
        mRow  = 2;
        sRow  = 0;
        tRow  = 1;
        tSign = -1.0f;
        break;
    default:
        DE_ASSERT(false);
        return;
    }

    dst.resize(4 * 4);

    dst[0 + mRow]  = mSign;
    dst[4 + mRow]  = mSign;
    dst[8 + mRow]  = mSign;
    dst[12 + mRow] = mSign;

    dst[0 + sRow]  = sSign * bottomLeft.x();
    dst[4 + sRow]  = sSign * bottomLeft.x();
    dst[8 + sRow]  = sSign * topRight.x();
    dst[12 + sRow] = sSign * topRight.x();

    dst[0 + tRow]  = tSign * bottomLeft.y();
    dst[4 + tRow]  = tSign * topRight.y();
    dst[8 + tRow]  = tSign * bottomLeft.y();
    dst[12 + tRow] = tSign * topRight.y();

    if (l0 != l1)
    {
        dst[0 + qRow]  = l0;
        dst[4 + qRow]  = l0 * 0.5f + l1 * 0.5f;
        dst[8 + qRow]  = l0 * 0.5f + l1 * 0.5f;
        dst[12 + qRow] = l1;
    }
    else
    {
        dst[0 + qRow]  = l0;
        dst[4 + qRow]  = l0;
        dst[8 + qRow]  = l0;
        dst[12 + qRow] = l0;
    }
}

// Texture result verification

//! Verifies texture lookup results and returns number of failed pixels.
int computeTextureLookupDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                             const tcu::PixelBufferAccess &errorMask, const tcu::Texture1DView &baseView,
                             const float *texCoord, const ReferenceParams &sampleParams,
                             const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                             qpWatchDog *watchDog)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::Texture1DView src =
        getEffectiveTextureView(getSubView(baseView, sampleParams.baseLevel, sampleParams.maxLevel, DE_NULL),
                                srcLevelStorage, sampleParams.sampler);

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0], texCoord[1], texCoord[2], texCoord[3]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const int srcSize        = src.getWidth();

    // Coordinates and lod per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        // Ugly hack, validation can take way too long at the moment.
        if (watchDog)
            qpWatchDog_touch(watchDog);

        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = (result.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;
            const tcu::Vec4 refPix = (reference.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;

            // Try comparison to ideal reference first, and if that fails use slower verificator.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(resPix - refPix), lookupPrec.colorThreshold)))
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
                const float triWx = triNdx ? dstW - wx : wx;
                const float triWy = triNdx ? dstH - wy : wy;
                const float triNx = triNdx ? 1.0f - nx : nx;
                const float triNy = triNdx ? 1.0f - ny : ny;

                const float coord   = projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy);
                const float coordDx = triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy) * float(srcSize);
                const float coordDy = triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx) * float(srcSize);

                tcu::Vec2 lodBounds = tcu::computeLodBoundsFromDerivates(coordDx, coordDy, lodPrec);

                // Compute lod bounds across lodOffsets range.
                for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                {
                    const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                    const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                    const float nxo = wxo / dstW;
                    const float nyo = wyo / dstH;

                    const float coordDxo = triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo) * float(srcSize);
                    const float coordDyo = triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo) * float(srcSize);
                    const tcu::Vec2 lodO = tcu::computeLodBoundsFromDerivates(coordDxo, coordDyo, lodPrec);

                    lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                    lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                }

                const tcu::Vec2 clampedLod = tcu::clampLodBounds(
                    lodBounds + lodBias, tcu::Vec2(sampleParams.minLod, sampleParams.maxLod), lodPrec);
                const bool isOk =
                    tcu::isLookupResultValid(src, sampleParams.sampler, lookupPrec, coord, clampedLod, resPix);

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

int computeTextureLookupDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                             const tcu::PixelBufferAccess &errorMask, const tcu::Texture2DView &baseView,
                             const float *texCoord, const ReferenceParams &sampleParams,
                             const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                             qpWatchDog *watchDog)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    tcu::ImageViewMinLodParams minLodParams = {
        sampleParams.baseLevel, // int baseLevel;
        {
            sampleParams.imageViewMinLod,     // float minLod;
            sampleParams.imageViewMinLodMode, // ImageViewMinLodMode
        },
        sampleParams.samplerType == SAMPLERTYPE_FETCH_FLOAT // bool intTexCoord;
    };

    const tcu::Texture2DView view = getSubView(baseView, sampleParams.baseLevel, sampleParams.maxLevel,
                                               sampleParams.imageViewMinLod != 0.0f ? &minLodParams : DE_NULL);

    const tcu::Texture2DView src = getEffectiveTextureView(view, srcLevelStorage, sampleParams.sampler);

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[2 + 0], texCoord[4 + 0], texCoord[6 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[2 + 1], texCoord[4 + 1], texCoord[6 + 1]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const tcu::IVec2 srcSize = tcu::IVec2(src.getWidth(), src.getHeight());

    // Coordinates and lod per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    // imageViewMinLodRel is used to calculate the image level to sample from, when VK_EXT_image_view_min_lod extension is enabled.
    // The value is relative to baseLevel as the Texture*View 'src' was created as the baseLevel being level[0].
    const float imageViewMinLodRel = sampleParams.imageViewMinLod - (float)sampleParams.baseLevel;
    // We need to adapt ImageView's minLod value to the mipmap mdoe (i.e. nearest or linear) so we clamp with the right minLod value later.
    const float imageViewMinLodRelMode = tcu::isSamplerMipmapModeLinear(sampleParams.sampler.minFilter) ?
                                             deFloatFloor(imageViewMinLodRel) :
                                             (float)deClamp32((int)deFloatCeil(imageViewMinLodRel + 0.5f) - 1,
                                                              sampleParams.baseLevel, sampleParams.maxLevel);
    const float minLod = (sampleParams.imageViewMinLod != 0.0f) ? de::max(imageViewMinLodRelMode, sampleParams.minLod) :
                                                                  sampleParams.minLod;

    const float posEps = 1.0f / float(1 << MIN_SUBPIXEL_BITS);

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        // Ugly hack, validation can take way too long at the moment.
        if (watchDog)
            qpWatchDog_touch(watchDog);

        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = (result.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;
            const tcu::Vec4 refPix = (reference.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;

            // Try comparison to ideal reference first, and if that fails use slower verificator.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(resPix - refPix), lookupPrec.colorThreshold)))
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const bool tri0 = (wx - posEps) / dstW + (wy - posEps) / dstH <= 1.0f;
                const bool tri1 = (wx + posEps) / dstW + (wy + posEps) / dstH >= 1.0f;

                bool isOk = false;

                DE_ASSERT(tri0 || tri1);

                // Pixel can belong to either of the triangles if it lies close enough to the edge.
                for (int triNdx = (tri0 ? 0 : 1); triNdx <= (tri1 ? 1 : 0); triNdx++)
                {
                    const float triWx = triNdx ? dstW - wx : wx;
                    const float triWy = triNdx ? dstH - wy : wy;
                    const float triNx = triNdx ? 1.0f - nx : nx;
                    const float triNy = triNdx ? 1.0f - ny : ny;

                    const tcu::Vec2 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                          projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy));
                    const tcu::Vec2 coordDx = tcu::Vec2(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                                        triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy)) *
                                              srcSize.asFloat();
                    const tcu::Vec2 coordDy = tcu::Vec2(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                                        triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx)) *
                                              srcSize.asFloat();

                    tcu::Vec2 lodBounds =
                        tcu::computeLodBoundsFromDerivates(coordDx.x(), coordDx.y(), coordDy.x(), coordDy.y(), lodPrec);

                    // Compute lod bounds across lodOffsets range.
                    for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                    {
                        const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                        const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                        const float nxo = wxo / dstW;
                        const float nyo = wyo / dstH;

                        const tcu::Vec2 coordDxo = tcu::Vec2(triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo),
                                                             triDerivateX(triT[triNdx], triW[triNdx], wxo, dstW, nyo)) *
                                                   srcSize.asFloat();
                        const tcu::Vec2 coordDyo = tcu::Vec2(triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo),
                                                             triDerivateY(triT[triNdx], triW[triNdx], wyo, dstH, nxo)) *
                                                   srcSize.asFloat();
                        const tcu::Vec2 lodO = tcu::computeLodBoundsFromDerivates(coordDxo.x(), coordDxo.y(),
                                                                                  coordDyo.x(), coordDyo.y(), lodPrec);

                        lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                        lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                    }

                    const tcu::Vec2 clampedLod =
                        tcu::clampLodBounds(lodBounds + lodBias, tcu::Vec2(minLod, sampleParams.maxLod), lodPrec);
                    if (tcu::isLookupResultValid(src, sampleParams.sampler, lookupPrec, coord, clampedLod, resPix))
                    {
                        isOk = true;
                        break;
                    }
                }

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

bool verifyTextureResult(tcu::TestContext &testCtx, const tcu::ConstPixelBufferAccess &result,
                         const tcu::Texture1DView &src, const float *texCoord, const ReferenceParams &sampleParams,
                         const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                         const tcu::PixelFormat &pixelFormat)
{
    tcu::TestLog &log = testCtx.getLog();
    tcu::Surface reference(result.getWidth(), result.getHeight());
    tcu::Surface errorMask(result.getWidth(), result.getHeight());
    int numFailedPixels;

    DE_ASSERT(getCompareMask(pixelFormat) == lookupPrec.colorMask);

    sampleTexture(tcu::SurfaceAccess(reference, pixelFormat), src, texCoord, sampleParams);
    numFailedPixels = computeTextureLookupDiff(result, reference.getAccess(), errorMask.getAccess(), src, texCoord,
                                               sampleParams, lookupPrec, lodPrec, testCtx.getWatchDog());

    if (numFailedPixels > 0)
        log << tcu::TestLog::Message << "ERROR: Result verification failed, got " << numFailedPixels
            << " invalid pixels!" << tcu::TestLog::EndMessage;

    log << tcu::TestLog::ImageSet("VerifyResult", "Verification result")
        << tcu::TestLog::Image("Rendered", "Rendered image", result);

    if (numFailedPixels > 0)
    {
        log << tcu::TestLog::Image("Reference", "Ideal reference image", reference)
            << tcu::TestLog::Image("ErrorMask", "Error mask", errorMask);
    }

    log << tcu::TestLog::EndImageSet;

    return numFailedPixels == 0;
}

bool verifyTextureResult(tcu::TestContext &testCtx, const tcu::ConstPixelBufferAccess &result,
                         const tcu::Texture2DView &src, const float *texCoord, const ReferenceParams &sampleParams,
                         const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                         const tcu::PixelFormat &pixelFormat)
{
    tcu::TestLog &log = testCtx.getLog();
    tcu::Surface reference(result.getWidth(), result.getHeight());
    tcu::Surface errorMask(result.getWidth(), result.getHeight());
    int numFailedPixels;

    DE_ASSERT(getCompareMask(pixelFormat) == lookupPrec.colorMask);

    sampleTexture(tcu::SurfaceAccess(reference, pixelFormat), src, texCoord, sampleParams);
    numFailedPixels = computeTextureLookupDiff(result, reference.getAccess(), errorMask.getAccess(), src, texCoord,
                                               sampleParams, lookupPrec, lodPrec, testCtx.getWatchDog());

    if (numFailedPixels > 0)
        log << tcu::TestLog::Message << "ERROR: Result verification failed, got " << numFailedPixels
            << " invalid pixels!" << tcu::TestLog::EndMessage;

    log << tcu::TestLog::ImageSet("VerifyResult", "Verification result")
        << tcu::TestLog::Image("Rendered", "Rendered image", result);

    if (numFailedPixels > 0)
    {
        log << tcu::TestLog::Image("Reference", "Ideal reference image", reference)
            << tcu::TestLog::Image("ErrorMask", "Error mask", errorMask);
    }

    log << tcu::TestLog::EndImageSet;

    return numFailedPixels == 0;
}

//! Verifies texture lookup results and returns number of failed pixels.
int computeTextureLookupDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                             const tcu::PixelBufferAccess &errorMask, const tcu::TextureCubeView &baseView,
                             const float *texCoord, const ReferenceParams &sampleParams,
                             const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                             qpWatchDog *watchDog)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    tcu::ImageViewMinLodParams minLodParams = {
        sampleParams.baseLevel, // int baseLevel;
        {
            sampleParams.imageViewMinLod,     // float minLod;
            sampleParams.imageViewMinLodMode, // ImageViewMinLodMode
        },
        sampleParams.samplerType == SAMPLERTYPE_FETCH_FLOAT // bool intTexCoord;
    };

    const tcu::TextureCubeView src =
        getEffectiveTextureView(getSubView(baseView, sampleParams.baseLevel, sampleParams.maxLevel,
                                           sampleParams.imageViewMinLod != 0.0f ? &minLodParams : DE_NULL),
                                srcLevelStorage, sampleParams.sampler);

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[3 + 0], texCoord[6 + 0], texCoord[9 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[3 + 1], texCoord[6 + 1], texCoord[9 + 1]);
    const tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[3 + 2], texCoord[6 + 2], texCoord[9 + 2]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const int srcSize        = src.getSize();

    // Coordinates per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    const float posEps = 1.0f / float(1 << MIN_SUBPIXEL_BITS);

    // imageViewMinLodRel is used to calculate the image level to sample from, when VK_EXT_image_view_min_lod extension is enabled.
    // The value is relative to baseLevel as the Texture*View 'src' was created as the baseLevel being level[0].
    const float imageViewMinLodRel = sampleParams.imageViewMinLod - (float)sampleParams.baseLevel;
    // We need to adapt ImageView's minLod value to the mipmap mdoe (i.e. nearest or linear) so we clamp with the right minLod value later.
    const float imageViewMinLodRelMode = tcu::isSamplerMipmapModeLinear(sampleParams.sampler.minFilter) ?
                                             deFloatFloor(imageViewMinLodRel) :
                                             (float)deClamp32((int)deFloatCeil(imageViewMinLodRel + 0.5f) - 1,
                                                              sampleParams.baseLevel, sampleParams.maxLevel);
    const float minLod = (sampleParams.imageViewMinLod != 0.0f) ? de::max(imageViewMinLodRelMode, sampleParams.minLod) :
                                                                  sampleParams.minLod;

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),

        // \note Not strictly allowed by spec, but implementations do this in practice.
        tcu::Vec2(-1, -1),
        tcu::Vec2(-1, +1),
        tcu::Vec2(+1, -1),
        tcu::Vec2(+1, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        // Ugly hack, validation can take way too long at the moment.
        if (watchDog)
            qpWatchDog_touch(watchDog);

        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = (result.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;
            const tcu::Vec4 refPix = (reference.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;

            // Try comparison to ideal reference first, and if that fails use slower verificator.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(resPix - refPix), lookupPrec.colorThreshold)))
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const bool tri0 = (wx - posEps) / dstW + (wy - posEps) / dstH <= 1.0f;
                const bool tri1 = (wx + posEps) / dstW + (wy + posEps) / dstH >= 1.0f;

                bool isOk = false;

                DE_ASSERT(tri0 || tri1);

                // Pixel can belong to either of the triangles if it lies close enough to the edge.
                for (int triNdx = (tri0 ? 0 : 1); triNdx <= (tri1 ? 1 : 0); triNdx++)
                {
                    const float triWx = triNdx ? dstW - wx : wx;
                    const float triWy = triNdx ? dstH - wy : wy;
                    const float triNx = triNdx ? 1.0f - nx : nx;
                    const float triNy = triNdx ? 1.0f - ny : ny;

                    const tcu::Vec3 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                          projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy),
                                          projectedTriInterpolate(triR[triNdx], triW[triNdx], triNx, triNy));
                    const tcu::Vec3 coordDx(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                            triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy),
                                            triDerivateX(triR[triNdx], triW[triNdx], wx, dstW, triNy));
                    const tcu::Vec3 coordDy(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                            triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx),
                                            triDerivateY(triR[triNdx], triW[triNdx], wy, dstH, triNx));

                    tcu::Vec2 lodBounds =
                        tcu::computeCubeLodBoundsFromDerivates(coord, coordDx, coordDy, srcSize, lodPrec);

                    // Compute lod bounds across lodOffsets range.
                    for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                    {
                        const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                        const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                        const float nxo = wxo / dstW;
                        const float nyo = wyo / dstH;

                        const tcu::Vec3 coordO(projectedTriInterpolate(triS[triNdx], triW[triNdx], nxo, nyo),
                                               projectedTriInterpolate(triT[triNdx], triW[triNdx], nxo, nyo),
                                               projectedTriInterpolate(triR[triNdx], triW[triNdx], nxo, nyo));
                        const tcu::Vec3 coordDxo(triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo),
                                                 triDerivateX(triT[triNdx], triW[triNdx], wxo, dstW, nyo),
                                                 triDerivateX(triR[triNdx], triW[triNdx], wxo, dstW, nyo));
                        const tcu::Vec3 coordDyo(triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo),
                                                 triDerivateY(triT[triNdx], triW[triNdx], wyo, dstH, nxo),
                                                 triDerivateY(triR[triNdx], triW[triNdx], wyo, dstH, nxo));
                        const tcu::Vec2 lodO =
                            tcu::computeCubeLodBoundsFromDerivates(coordO, coordDxo, coordDyo, srcSize, lodPrec);

                        lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                        lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                    }

                    const tcu::Vec2 clampedLod =
                        tcu::clampLodBounds(lodBounds + lodBias, tcu::Vec2(minLod, sampleParams.maxLod), lodPrec);

                    if (tcu::isLookupResultValid(src, sampleParams.sampler, lookupPrec, coord, clampedLod, resPix))
                    {
                        isOk = true;
                        break;
                    }
                }

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

bool verifyTextureResult(tcu::TestContext &testCtx, const tcu::ConstPixelBufferAccess &result,
                         const tcu::TextureCubeView &src, const float *texCoord, const ReferenceParams &sampleParams,
                         const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                         const tcu::PixelFormat &pixelFormat)
{
    tcu::TestLog &log = testCtx.getLog();
    tcu::Surface reference(result.getWidth(), result.getHeight());
    tcu::Surface errorMask(result.getWidth(), result.getHeight());
    int numFailedPixels;

    DE_ASSERT(getCompareMask(pixelFormat) == lookupPrec.colorMask);

    sampleTexture(tcu::SurfaceAccess(reference, pixelFormat), src, texCoord, sampleParams);
    numFailedPixels = computeTextureLookupDiff(result, reference.getAccess(), errorMask.getAccess(), src, texCoord,
                                               sampleParams, lookupPrec, lodPrec, testCtx.getWatchDog());

    if (numFailedPixels > 0)
        log << tcu::TestLog::Message << "ERROR: Result verification failed, got " << numFailedPixels
            << " invalid pixels!" << tcu::TestLog::EndMessage;

    log << tcu::TestLog::ImageSet("VerifyResult", "Verification result")
        << tcu::TestLog::Image("Rendered", "Rendered image", result);

    if (numFailedPixels > 0)
    {
        log << tcu::TestLog::Image("Reference", "Ideal reference image", reference)
            << tcu::TestLog::Image("ErrorMask", "Error mask", errorMask);
    }

    log << tcu::TestLog::EndImageSet;

    return numFailedPixels == 0;
}

//! Verifies texture lookup results and returns number of failed pixels.
int computeTextureLookupDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                             const tcu::PixelBufferAccess &errorMask, const tcu::Texture3DView &baseView,
                             const float *texCoord, const ReferenceParams &sampleParams,
                             const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                             qpWatchDog *watchDog)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    tcu::ImageViewMinLodParams minLodParams = {
        sampleParams.baseLevel, // int baseLevel;
        {
            sampleParams.imageViewMinLod,     // float minLod;
            sampleParams.imageViewMinLodMode, // ImageViewMinLodMode
        },
        sampleParams.samplerType == SAMPLERTYPE_FETCH_FLOAT // bool intTexCoord;
    };

    const tcu::Texture3DView src =
        getEffectiveTextureView(getSubView(baseView, sampleParams.baseLevel, sampleParams.maxLevel,
                                           sampleParams.imageViewMinLod != 0.0f ? &minLodParams : DE_NULL),
                                srcLevelStorage, sampleParams.sampler);

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[3 + 0], texCoord[6 + 0], texCoord[9 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[3 + 1], texCoord[6 + 1], texCoord[9 + 1]);
    const tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[3 + 2], texCoord[6 + 2], texCoord[9 + 2]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const tcu::IVec3 srcSize = tcu::IVec3(src.getWidth(), src.getHeight(), src.getDepth());

    // Coordinates and lod per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    // imageViewMinLodRel is used to calculate the image level to sample from, when VK_EXT_image_view_min_lod extension is enabled.
    // The value is relative to baseLevel as the Texture*View 'src' was created as the baseLevel being level[0].
    const float imageViewMinLodRel = sampleParams.imageViewMinLod - (float)sampleParams.baseLevel;
    // We need to adapt ImageView's minLod value to the mipmap mdoe (i.e. nearest or linear) so we clamp with the right minLod value later.
    const float imageViewMinLodRelMode = tcu::isSamplerMipmapModeLinear(sampleParams.sampler.minFilter) ?
                                             deFloatFloor(imageViewMinLodRel) :
                                             (float)deClamp32((int)deFloatCeil(imageViewMinLodRel + 0.5f) - 1,
                                                              sampleParams.baseLevel, sampleParams.maxLevel);
    const float minLod = (sampleParams.imageViewMinLod != 0.0f) ? de::max(imageViewMinLodRelMode, sampleParams.minLod) :
                                                                  sampleParams.minLod;

    const float posEps = 1.0f / float(1 << MIN_SUBPIXEL_BITS);

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        // Ugly hack, validation can take way too long at the moment.
        if (watchDog)
            qpWatchDog_touch(watchDog);

        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = (result.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;
            const tcu::Vec4 refPix = (reference.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;

            // Try comparison to ideal reference first, and if that fails use slower verificator.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(resPix - refPix), lookupPrec.colorThreshold)))
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const bool tri0 = (wx - posEps) / dstW + (wy - posEps) / dstH <= 1.0f;
                const bool tri1 = (wx + posEps) / dstW + (wy + posEps) / dstH >= 1.0f;

                bool isOk = false;

                DE_ASSERT(tri0 || tri1);

                // Pixel can belong to either of the triangles if it lies close enough to the edge.
                for (int triNdx = (tri0 ? 0 : 1); triNdx <= (tri1 ? 1 : 0); triNdx++)
                {
                    const float triWx = triNdx ? dstW - wx : wx;
                    const float triWy = triNdx ? dstH - wy : wy;
                    const float triNx = triNdx ? 1.0f - nx : nx;
                    const float triNy = triNdx ? 1.0f - ny : ny;

                    const tcu::Vec3 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                          projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy),
                                          projectedTriInterpolate(triR[triNdx], triW[triNdx], triNx, triNy));
                    const tcu::Vec3 coordDx = tcu::Vec3(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                                        triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy),
                                                        triDerivateX(triR[triNdx], triW[triNdx], wx, dstW, triNy)) *
                                              srcSize.asFloat();
                    const tcu::Vec3 coordDy = tcu::Vec3(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                                        triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx),
                                                        triDerivateY(triR[triNdx], triW[triNdx], wy, dstH, triNx)) *
                                              srcSize.asFloat();

                    tcu::Vec2 lodBounds = tcu::computeLodBoundsFromDerivates(
                        coordDx.x(), coordDx.y(), coordDx.z(), coordDy.x(), coordDy.y(), coordDy.z(), lodPrec);

                    // Compute lod bounds across lodOffsets range.
                    for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                    {
                        const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                        const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                        const float nxo = wxo / dstW;
                        const float nyo = wyo / dstH;

                        const tcu::Vec3 coordDxo = tcu::Vec3(triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo),
                                                             triDerivateX(triT[triNdx], triW[triNdx], wxo, dstW, nyo),
                                                             triDerivateX(triR[triNdx], triW[triNdx], wxo, dstW, nyo)) *
                                                   srcSize.asFloat();
                        const tcu::Vec3 coordDyo = tcu::Vec3(triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo),
                                                             triDerivateY(triT[triNdx], triW[triNdx], wyo, dstH, nxo),
                                                             triDerivateY(triR[triNdx], triW[triNdx], wyo, dstH, nxo)) *
                                                   srcSize.asFloat();
                        const tcu::Vec2 lodO =
                            tcu::computeLodBoundsFromDerivates(coordDxo.x(), coordDxo.y(), coordDxo.z(), coordDyo.x(),
                                                               coordDyo.y(), coordDyo.z(), lodPrec);

                        lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                        lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                    }

                    const tcu::Vec2 clampedLod =
                        tcu::clampLodBounds(lodBounds + lodBias, tcu::Vec2(minLod, sampleParams.maxLod), lodPrec);

                    if (tcu::isLookupResultValid(src, sampleParams.sampler, lookupPrec, coord, clampedLod, resPix))
                    {
                        isOk = true;
                        break;
                    }
                }

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

bool verifyTextureResult(tcu::TestContext &testCtx, const tcu::ConstPixelBufferAccess &result,
                         const tcu::Texture3DView &src, const float *texCoord, const ReferenceParams &sampleParams,
                         const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                         const tcu::PixelFormat &pixelFormat)
{
    tcu::TestLog &log = testCtx.getLog();
    tcu::Surface reference(result.getWidth(), result.getHeight());
    tcu::Surface errorMask(result.getWidth(), result.getHeight());
    int numFailedPixels;

    DE_ASSERT(getCompareMask(pixelFormat) == lookupPrec.colorMask);

    sampleTexture(tcu::SurfaceAccess(reference, pixelFormat), src, texCoord, sampleParams);
    numFailedPixels = computeTextureLookupDiff(result, reference.getAccess(), errorMask.getAccess(), src, texCoord,
                                               sampleParams, lookupPrec, lodPrec, testCtx.getWatchDog());

    if (numFailedPixels > 0)
        log << tcu::TestLog::Message << "ERROR: Result verification failed, got " << numFailedPixels
            << " invalid pixels!" << tcu::TestLog::EndMessage;

    log << tcu::TestLog::ImageSet("VerifyResult", "Verification result")
        << tcu::TestLog::Image("Rendered", "Rendered image", result);

    if (numFailedPixels > 0)
    {
        log << tcu::TestLog::Image("Reference", "Ideal reference image", reference)
            << tcu::TestLog::Image("ErrorMask", "Error mask", errorMask);
    }

    log << tcu::TestLog::EndImageSet;

    return numFailedPixels == 0;
}

//! Verifies texture lookup results and returns number of failed pixels.
int computeTextureLookupDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                             const tcu::PixelBufferAccess &errorMask, const tcu::Texture1DArrayView &baseView,
                             const float *texCoord, const ReferenceParams &sampleParams,
                             const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                             qpWatchDog *watchDog)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::Texture1DArrayView src = getEffectiveTextureView(baseView, srcLevelStorage, sampleParams.sampler);

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[2 + 0], texCoord[4 + 0], texCoord[6 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[2 + 1], texCoord[4 + 1], texCoord[6 + 1]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const float srcSize      = float(src.getWidth()); // For lod computation, thus #layers is ignored.

    // Coordinates and lod per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        // Ugly hack, validation can take way too long at the moment.
        if (watchDog)
            qpWatchDog_touch(watchDog);

        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = (result.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;
            const tcu::Vec4 refPix = (reference.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;

            // Try comparison to ideal reference first, and if that fails use slower verificator.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(resPix - refPix), lookupPrec.colorThreshold)))
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
                const float triWx = triNdx ? dstW - wx : wx;
                const float triWy = triNdx ? dstH - wy : wy;
                const float triNx = triNdx ? 1.0f - nx : nx;
                const float triNy = triNdx ? 1.0f - ny : ny;

                const tcu::Vec2 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy));
                const float coordDx = triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy) * srcSize;
                const float coordDy = triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx) * srcSize;

                tcu::Vec2 lodBounds = tcu::computeLodBoundsFromDerivates(coordDx, coordDy, lodPrec);

                // Compute lod bounds across lodOffsets range.
                for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                {
                    const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                    const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                    const float nxo = wxo / dstW;
                    const float nyo = wyo / dstH;

                    const float coordDxo = triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo) * srcSize;
                    const float coordDyo = triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo) * srcSize;
                    const tcu::Vec2 lodO = tcu::computeLodBoundsFromDerivates(coordDxo, coordDyo, lodPrec);

                    lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                    lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                }

                const tcu::Vec2 clampedLod = tcu::clampLodBounds(
                    lodBounds + lodBias, tcu::Vec2(sampleParams.minLod, sampleParams.maxLod), lodPrec);
                const bool isOk =
                    tcu::isLookupResultValid(src, sampleParams.sampler, lookupPrec, coord, clampedLod, resPix);

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

//! Verifies texture lookup results and returns number of failed pixels.
int computeTextureLookupDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                             const tcu::PixelBufferAccess &errorMask, const tcu::Texture2DArrayView &baseView,
                             const float *texCoord, const ReferenceParams &sampleParams,
                             const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                             qpWatchDog *watchDog)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    const tcu::Texture2DArrayView src = getEffectiveTextureView(baseView, srcLevelStorage, sampleParams.sampler);

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[3 + 0], texCoord[6 + 0], texCoord[9 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[3 + 1], texCoord[6 + 1], texCoord[9 + 1]);
    const tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[3 + 2], texCoord[6 + 2], texCoord[9 + 2]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const tcu::Vec2 srcSize =
        tcu::IVec2(src.getWidth(), src.getHeight()).asFloat(); // For lod computation, thus #layers is ignored.

    // Coordinates and lod per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        // Ugly hack, validation can take way too long at the moment.
        if (watchDog)
            qpWatchDog_touch(watchDog);

        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = (result.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;
            const tcu::Vec4 refPix = (reference.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;

            // Try comparison to ideal reference first, and if that fails use slower verificator.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(resPix - refPix), lookupPrec.colorThreshold)))
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
                const float triWx = triNdx ? dstW - wx : wx;
                const float triWy = triNdx ? dstH - wy : wy;
                const float triNx = triNdx ? 1.0f - nx : nx;
                const float triNy = triNdx ? 1.0f - ny : ny;

                const tcu::Vec3 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triR[triNdx], triW[triNdx], triNx, triNy));
                const tcu::Vec2 coordDx = tcu::Vec2(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                                    triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy)) *
                                          srcSize;
                const tcu::Vec2 coordDy = tcu::Vec2(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                                    triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx)) *
                                          srcSize;

                tcu::Vec2 lodBounds =
                    tcu::computeLodBoundsFromDerivates(coordDx.x(), coordDx.y(), coordDy.x(), coordDy.y(), lodPrec);

                // Compute lod bounds across lodOffsets range.
                for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                {
                    const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                    const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                    const float nxo = wxo / dstW;
                    const float nyo = wyo / dstH;

                    const tcu::Vec2 coordDxo = tcu::Vec2(triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo),
                                                         triDerivateX(triT[triNdx], triW[triNdx], wxo, dstW, nyo)) *
                                               srcSize;
                    const tcu::Vec2 coordDyo = tcu::Vec2(triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo),
                                                         triDerivateY(triT[triNdx], triW[triNdx], wyo, dstH, nxo)) *
                                               srcSize;
                    const tcu::Vec2 lodO = tcu::computeLodBoundsFromDerivates(coordDxo.x(), coordDxo.y(), coordDyo.x(),
                                                                              coordDyo.y(), lodPrec);

                    lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                    lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                }

                const tcu::Vec2 clampedLod = tcu::clampLodBounds(
                    lodBounds + lodBias, tcu::Vec2(sampleParams.minLod, sampleParams.maxLod), lodPrec);
                const bool isOk =
                    tcu::isLookupResultValid(src, sampleParams.sampler, lookupPrec, coord, clampedLod, resPix);

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

bool verifyTextureResult(tcu::TestContext &testCtx, const tcu::ConstPixelBufferAccess &result,
                         const tcu::Texture1DArrayView &src, const float *texCoord, const ReferenceParams &sampleParams,
                         const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                         const tcu::PixelFormat &pixelFormat)
{
    tcu::TestLog &log = testCtx.getLog();
    tcu::Surface reference(result.getWidth(), result.getHeight());
    tcu::Surface errorMask(result.getWidth(), result.getHeight());
    int numFailedPixels;

    DE_ASSERT(getCompareMask(pixelFormat) == lookupPrec.colorMask);

    sampleTexture(tcu::SurfaceAccess(reference, pixelFormat), src, texCoord, sampleParams);
    numFailedPixels = computeTextureLookupDiff(result, reference.getAccess(), errorMask.getAccess(), src, texCoord,
                                               sampleParams, lookupPrec, lodPrec, testCtx.getWatchDog());

    if (numFailedPixels > 0)
        log << tcu::TestLog::Message << "ERROR: Result verification failed, got " << numFailedPixels
            << " invalid pixels!" << tcu::TestLog::EndMessage;

    log << tcu::TestLog::ImageSet("VerifyResult", "Verification result")
        << tcu::TestLog::Image("Rendered", "Rendered image", result);

    if (numFailedPixels > 0)
    {
        log << tcu::TestLog::Image("Reference", "Ideal reference image", reference)
            << tcu::TestLog::Image("ErrorMask", "Error mask", errorMask);
    }

    log << tcu::TestLog::EndImageSet;

    return numFailedPixels == 0;
}

bool verifyTextureResult(tcu::TestContext &testCtx, const tcu::ConstPixelBufferAccess &result,
                         const tcu::Texture2DArrayView &src, const float *texCoord, const ReferenceParams &sampleParams,
                         const tcu::LookupPrecision &lookupPrec, const tcu::LodPrecision &lodPrec,
                         const tcu::PixelFormat &pixelFormat)
{
    tcu::TestLog &log = testCtx.getLog();
    tcu::Surface reference(result.getWidth(), result.getHeight());
    tcu::Surface errorMask(result.getWidth(), result.getHeight());
    int numFailedPixels;

    DE_ASSERT(getCompareMask(pixelFormat) == lookupPrec.colorMask);

    sampleTexture(tcu::SurfaceAccess(reference, pixelFormat), src, texCoord, sampleParams);
    numFailedPixels = computeTextureLookupDiff(result, reference.getAccess(), errorMask.getAccess(), src, texCoord,
                                               sampleParams, lookupPrec, lodPrec, testCtx.getWatchDog());

    if (numFailedPixels > 0)
        log << tcu::TestLog::Message << "ERROR: Result verification failed, got " << numFailedPixels
            << " invalid pixels!" << tcu::TestLog::EndMessage;

    log << tcu::TestLog::ImageSet("VerifyResult", "Verification result")
        << tcu::TestLog::Image("Rendered", "Rendered image", result);

    if (numFailedPixels > 0)
    {
        log << tcu::TestLog::Image("Reference", "Ideal reference image", reference)
            << tcu::TestLog::Image("ErrorMask", "Error mask", errorMask);
    }

    log << tcu::TestLog::EndImageSet;

    return numFailedPixels == 0;
}

//! Verifies texture lookup results and returns number of failed pixels.
int computeTextureLookupDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                             const tcu::PixelBufferAccess &errorMask, const tcu::TextureCubeArrayView &baseView,
                             const float *texCoord, const ReferenceParams &sampleParams,
                             const tcu::LookupPrecision &lookupPrec, const tcu::IVec4 &coordBits,
                             const tcu::LodPrecision &lodPrec, qpWatchDog *watchDog)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    std::vector<tcu::ConstPixelBufferAccess> srcLevelStorage;
    tcu::ImageViewMinLodParams minLodParams = {
        sampleParams.baseLevel, // int baseLevel;
        {
            sampleParams.imageViewMinLod,     // float minLod;
            sampleParams.imageViewMinLodMode, // ImageViewMinLodMode
        },
        sampleParams.samplerType == SAMPLERTYPE_FETCH_FLOAT // bool intTexCoord;
    };

    const tcu::TextureCubeArrayView src =
        getEffectiveTextureView(getSubView(baseView, sampleParams.baseLevel, sampleParams.maxLevel,
                                           sampleParams.imageViewMinLod != 0.0f ? &minLodParams : DE_NULL),
                                srcLevelStorage, sampleParams.sampler);

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[4 + 0], texCoord[8 + 0], texCoord[12 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[4 + 1], texCoord[8 + 1], texCoord[12 + 1]);
    const tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[4 + 2], texCoord[8 + 2], texCoord[12 + 2]);
    const tcu::Vec4 qq = tcu::Vec4(texCoord[0 + 3], texCoord[4 + 3], texCoord[8 + 3], texCoord[12 + 3]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const int srcSize        = src.getSize();

    // Coordinates per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    const tcu::Vec3 triQ[2] = {qq.swizzle(0, 1, 2), qq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    const float posEps = 1.0f / float((1 << 4) + 1); // ES3 requires at least 4 subpixel bits.

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),

        // \note Not strictly allowed by spec, but implementations do this in practice.
        tcu::Vec2(-1, -1),
        tcu::Vec2(-1, +1),
        tcu::Vec2(+1, -1),
        tcu::Vec2(+1, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        // Ugly hack, validation can take way too long at the moment.
        if (watchDog)
            qpWatchDog_touch(watchDog);

        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = (result.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;
            const tcu::Vec4 refPix = (reference.getPixel(px, py) - sampleParams.colorBias) / sampleParams.colorScale;

            // Try comparison to ideal reference first, and if that fails use slower verificator.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(resPix - refPix), lookupPrec.colorThreshold)))
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const bool tri0 = nx + ny - posEps <= 1.0f;
                const bool tri1 = nx + ny + posEps >= 1.0f;

                bool isOk = false;

                DE_ASSERT(tri0 || tri1);

                // Pixel can belong to either of the triangles if it lies close enough to the edge.
                for (int triNdx = (tri0 ? 0 : 1); triNdx <= (tri1 ? 1 : 0); triNdx++)
                {
                    const float triWx = triNdx ? dstW - wx : wx;
                    const float triWy = triNdx ? dstH - wy : wy;
                    const float triNx = triNdx ? 1.0f - nx : nx;
                    const float triNy = triNdx ? 1.0f - ny : ny;

                    const tcu::Vec4 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                          projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy),
                                          projectedTriInterpolate(triR[triNdx], triW[triNdx], triNx, triNy),
                                          projectedTriInterpolate(triQ[triNdx], triW[triNdx], triNx, triNy));
                    const tcu::Vec3 coordDx(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                            triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy),
                                            triDerivateX(triR[triNdx], triW[triNdx], wx, dstW, triNy));
                    const tcu::Vec3 coordDy(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                            triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx),
                                            triDerivateY(triR[triNdx], triW[triNdx], wy, dstH, triNx));

                    tcu::Vec2 lodBounds =
                        tcu::computeCubeLodBoundsFromDerivates(coord.toWidth<3>(), coordDx, coordDy, srcSize, lodPrec);

                    // Compute lod bounds across lodOffsets range.
                    for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                    {
                        const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                        const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                        const float nxo = wxo / dstW;
                        const float nyo = wyo / dstH;

                        const tcu::Vec3 coordO(projectedTriInterpolate(triS[triNdx], triW[triNdx], nxo, nyo),
                                               projectedTriInterpolate(triT[triNdx], triW[triNdx], nxo, nyo),
                                               projectedTriInterpolate(triR[triNdx], triW[triNdx], nxo, nyo));
                        const tcu::Vec3 coordDxo(triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo),
                                                 triDerivateX(triT[triNdx], triW[triNdx], wxo, dstW, nyo),
                                                 triDerivateX(triR[triNdx], triW[triNdx], wxo, dstW, nyo));
                        const tcu::Vec3 coordDyo(triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo),
                                                 triDerivateY(triT[triNdx], triW[triNdx], wyo, dstH, nxo),
                                                 triDerivateY(triR[triNdx], triW[triNdx], wyo, dstH, nxo));
                        const tcu::Vec2 lodO =
                            tcu::computeCubeLodBoundsFromDerivates(coordO, coordDxo, coordDyo, srcSize, lodPrec);

                        lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                        lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                    }

                    const tcu::Vec2 clampedLod = tcu::clampLodBounds(
                        lodBounds + lodBias, tcu::Vec2(sampleParams.minLod, sampleParams.maxLod), lodPrec);

                    if (tcu::isLookupResultValid(src, sampleParams.sampler, lookupPrec, coordBits, coord, clampedLod,
                                                 resPix))
                    {
                        isOk = true;
                        break;
                    }
                }

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

bool verifyTextureResult(tcu::TestContext &testCtx, const tcu::ConstPixelBufferAccess &result,
                         const tcu::TextureCubeArrayView &src, const float *texCoord,
                         const ReferenceParams &sampleParams, const tcu::LookupPrecision &lookupPrec,
                         const tcu::IVec4 &coordBits, const tcu::LodPrecision &lodPrec,
                         const tcu::PixelFormat &pixelFormat)
{
    tcu::TestLog &log = testCtx.getLog();
    tcu::Surface reference(result.getWidth(), result.getHeight());
    tcu::Surface errorMask(result.getWidth(), result.getHeight());
    int numFailedPixels;

    DE_ASSERT(getCompareMask(pixelFormat) == lookupPrec.colorMask);

    sampleTexture(tcu::SurfaceAccess(reference, pixelFormat), src, texCoord, sampleParams);
    numFailedPixels = computeTextureLookupDiff(result, reference.getAccess(), errorMask.getAccess(), src, texCoord,
                                               sampleParams, lookupPrec, coordBits, lodPrec, testCtx.getWatchDog());

    if (numFailedPixels > 0)
        log << tcu::TestLog::Message << "ERROR: Result verification failed, got " << numFailedPixels
            << " invalid pixels!" << tcu::TestLog::EndMessage;

    log << tcu::TestLog::ImageSet("VerifyResult", "Verification result")
        << tcu::TestLog::Image("Rendered", "Rendered image", result);

    if (numFailedPixels > 0)
    {
        log << tcu::TestLog::Image("Reference", "Ideal reference image", reference)
            << tcu::TestLog::Image("ErrorMask", "Error mask", errorMask);
    }

    log << tcu::TestLog::EndImageSet;

    return numFailedPixels == 0;
}

// Shadow lookup verification

int computeTextureCompareDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                              const tcu::PixelBufferAccess &errorMask, const tcu::Texture2DView &src,
                              const float *texCoord, const ReferenceParams &sampleParams,
                              const tcu::TexComparePrecision &comparePrec, const tcu::LodPrecision &lodPrec,
                              const tcu::Vec3 &nonShadowThreshold)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[2 + 0], texCoord[4 + 0], texCoord[6 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[2 + 1], texCoord[4 + 1], texCoord[6 + 1]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const tcu::IVec2 srcSize = tcu::IVec2(src.getWidth(), src.getHeight());

    // Coordinates and lod per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    const float minLod = (sampleParams.imageViewMinLod != 0.0f) ?
                             de::max(deFloatFloor(sampleParams.imageViewMinLod), sampleParams.minLod) :
                             sampleParams.minLod;

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = result.getPixel(px, py);
            const tcu::Vec4 refPix = reference.getPixel(px, py);

            // Other channels should trivially match to reference.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(refPix.swizzle(1, 2, 3) - resPix.swizzle(1, 2, 3)),
                                                 nonShadowThreshold)))
            {
                errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                numFailed += 1;
                continue;
            }

            // Reference result is known to be a valid result, we can
            // skip verification if thes results are equal
            if (resPix.x() != refPix.x())
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
                const float triWx = triNdx ? dstW - wx : wx;
                const float triWy = triNdx ? dstH - wy : wy;
                const float triNx = triNdx ? 1.0f - nx : nx;
                const float triNy = triNdx ? 1.0f - ny : ny;

                const tcu::Vec2 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy));
                const tcu::Vec2 coordDx = tcu::Vec2(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                                    triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy)) *
                                          srcSize.asFloat();
                const tcu::Vec2 coordDy = tcu::Vec2(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                                    triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx)) *
                                          srcSize.asFloat();

                tcu::Vec2 lodBounds =
                    tcu::computeLodBoundsFromDerivates(coordDx.x(), coordDx.y(), coordDy.x(), coordDy.y(), lodPrec);

                // Compute lod bounds across lodOffsets range.
                for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                {
                    const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                    const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                    const float nxo = wxo / dstW;
                    const float nyo = wyo / dstH;

                    const tcu::Vec2 coordDxo = tcu::Vec2(triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo),
                                                         triDerivateX(triT[triNdx], triW[triNdx], wxo, dstW, nyo)) *
                                               srcSize.asFloat();
                    const tcu::Vec2 coordDyo = tcu::Vec2(triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo),
                                                         triDerivateY(triT[triNdx], triW[triNdx], wyo, dstH, nxo)) *
                                               srcSize.asFloat();
                    const tcu::Vec2 lodO = tcu::computeLodBoundsFromDerivates(coordDxo.x(), coordDxo.y(), coordDyo.x(),
                                                                              coordDyo.y(), lodPrec);

                    lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                    lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                }

                const tcu::Vec2 clampedLod =
                    tcu::clampLodBounds(lodBounds + lodBias, tcu::Vec2(minLod, sampleParams.maxLod), lodPrec);
                const bool isOk = tcu::isTexCompareResultValid(src, sampleParams.sampler, comparePrec, coord,
                                                               clampedLod, sampleParams.ref, resPix.x());

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

int computeTextureCompareDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                              const tcu::PixelBufferAccess &errorMask, const tcu::TextureCubeView &src,
                              const float *texCoord, const ReferenceParams &sampleParams,
                              const tcu::TexComparePrecision &comparePrec, const tcu::LodPrecision &lodPrec,
                              const tcu::Vec3 &nonShadowThreshold)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[3 + 0], texCoord[6 + 0], texCoord[9 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[3 + 1], texCoord[6 + 1], texCoord[9 + 1]);
    const tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[3 + 2], texCoord[6 + 2], texCoord[9 + 2]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const int srcSize        = src.getSize();

    // Coordinates per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    const float minLod = (sampleParams.imageViewMinLod != 0.0f) ?
                             de::max(deFloatFloor(sampleParams.imageViewMinLod), sampleParams.minLod) :
                             sampleParams.minLod;

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = result.getPixel(px, py);
            const tcu::Vec4 refPix = reference.getPixel(px, py);

            // Other channels should trivially match to reference.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(refPix.swizzle(1, 2, 3) - resPix.swizzle(1, 2, 3)),
                                                 nonShadowThreshold)))
            {
                errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                numFailed += 1;
                continue;
            }

            // Reference result is known to be a valid result, we can
            // skip verification if thes results are equal
            if (resPix.x() != refPix.x())
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
                const float triWx = triNdx ? dstW - wx : wx;
                const float triWy = triNdx ? dstH - wy : wy;
                const float triNx = triNdx ? 1.0f - nx : nx;
                const float triNy = triNdx ? 1.0f - ny : ny;

                const tcu::Vec3 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triR[triNdx], triW[triNdx], triNx, triNy));
                const tcu::Vec3 coordDx(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                        triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy),
                                        triDerivateX(triR[triNdx], triW[triNdx], wx, dstW, triNy));
                const tcu::Vec3 coordDy(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                        triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx),
                                        triDerivateY(triR[triNdx], triW[triNdx], wy, dstH, triNx));

                tcu::Vec2 lodBounds = tcu::computeCubeLodBoundsFromDerivates(coord, coordDx, coordDy, srcSize, lodPrec);

                // Compute lod bounds across lodOffsets range.
                for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                {
                    const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                    const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                    const float nxo = wxo / dstW;
                    const float nyo = wyo / dstH;

                    const tcu::Vec3 coordO(projectedTriInterpolate(triS[triNdx], triW[triNdx], nxo, nyo),
                                           projectedTriInterpolate(triT[triNdx], triW[triNdx], nxo, nyo),
                                           projectedTriInterpolate(triR[triNdx], triW[triNdx], nxo, nyo));
                    const tcu::Vec3 coordDxo(triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo),
                                             triDerivateX(triT[triNdx], triW[triNdx], wxo, dstW, nyo),
                                             triDerivateX(triR[triNdx], triW[triNdx], wxo, dstW, nyo));
                    const tcu::Vec3 coordDyo(triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo),
                                             triDerivateY(triT[triNdx], triW[triNdx], wyo, dstH, nxo),
                                             triDerivateY(triR[triNdx], triW[triNdx], wyo, dstH, nxo));
                    const tcu::Vec2 lodO =
                        tcu::computeCubeLodBoundsFromDerivates(coordO, coordDxo, coordDyo, srcSize, lodPrec);

                    lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                    lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                }

                const tcu::Vec2 clampedLod =
                    tcu::clampLodBounds(lodBounds + lodBias, tcu::Vec2(minLod, sampleParams.maxLod), lodPrec);
                const bool isOk = tcu::isTexCompareResultValid(src, sampleParams.sampler, comparePrec, coord,
                                                               clampedLod, sampleParams.ref, resPix.x());

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

int computeTextureCompareDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                              const tcu::PixelBufferAccess &errorMask, const tcu::Texture2DArrayView &src,
                              const float *texCoord, const ReferenceParams &sampleParams,
                              const tcu::TexComparePrecision &comparePrec, const tcu::LodPrecision &lodPrec,
                              const tcu::Vec3 &nonShadowThreshold)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[3 + 0], texCoord[6 + 0], texCoord[9 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[3 + 1], texCoord[6 + 1], texCoord[9 + 1]);
    const tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[3 + 2], texCoord[6 + 2], texCoord[9 + 2]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const tcu::IVec2 srcSize = tcu::IVec2(src.getWidth(), src.getHeight());

    // Coordinates and lod per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = result.getPixel(px, py);
            const tcu::Vec4 refPix = reference.getPixel(px, py);

            // Other channels should trivially match to reference.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(refPix.swizzle(1, 2, 3) - resPix.swizzle(1, 2, 3)),
                                                 nonShadowThreshold)))
            {
                errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                numFailed += 1;
                continue;
            }

            // Reference result is known to be a valid result, we can
            // skip verification if thes results are equal
            if (resPix.x() != refPix.x())
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
                const float triWx = triNdx ? dstW - wx : wx;
                const float triWy = triNdx ? dstH - wy : wy;
                const float triNx = triNdx ? 1.0f - nx : nx;
                const float triNy = triNdx ? 1.0f - ny : ny;

                const tcu::Vec3 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triR[triNdx], triW[triNdx], triNx, triNy));
                const tcu::Vec2 coordDx = tcu::Vec2(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                                    triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy)) *
                                          srcSize.asFloat();
                const tcu::Vec2 coordDy = tcu::Vec2(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                                    triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx)) *
                                          srcSize.asFloat();

                tcu::Vec2 lodBounds =
                    tcu::computeLodBoundsFromDerivates(coordDx.x(), coordDx.y(), coordDy.x(), coordDy.y(), lodPrec);

                // Compute lod bounds across lodOffsets range.
                for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                {
                    const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                    const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                    const float nxo = wxo / dstW;
                    const float nyo = wyo / dstH;

                    const tcu::Vec2 coordDxo = tcu::Vec2(triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo),
                                                         triDerivateX(triT[triNdx], triW[triNdx], wxo, dstW, nyo)) *
                                               srcSize.asFloat();
                    const tcu::Vec2 coordDyo = tcu::Vec2(triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo),
                                                         triDerivateY(triT[triNdx], triW[triNdx], wyo, dstH, nxo)) *
                                               srcSize.asFloat();
                    const tcu::Vec2 lodO = tcu::computeLodBoundsFromDerivates(coordDxo.x(), coordDxo.y(), coordDyo.x(),
                                                                              coordDyo.y(), lodPrec);

                    lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                    lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                }

                const tcu::Vec2 clampedLod = tcu::clampLodBounds(
                    lodBounds + lodBias, tcu::Vec2(sampleParams.minLod, sampleParams.maxLod), lodPrec);
                const bool isOk = tcu::isTexCompareResultValid(src, sampleParams.sampler, comparePrec, coord,
                                                               clampedLod, sampleParams.ref, resPix.x());

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

int computeTextureCompareDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                              const tcu::PixelBufferAccess &errorMask, const tcu::Texture1DView &src,
                              const float *texCoord, const ReferenceParams &sampleParams,
                              const tcu::TexComparePrecision &comparePrec, const tcu::LodPrecision &lodPrec,
                              const tcu::Vec3 &nonShadowThreshold)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());
    DE_ASSERT(result.getHeight() == 1);

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0], texCoord[1], texCoord[2], texCoord[3]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), 1);
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const float srcSize      = float(src.getWidth());

    // Coordinates and lod per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    const int py = 0;
    {
        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = result.getPixel(px, py);
            const tcu::Vec4 refPix = reference.getPixel(px, py);

            // Other channels should trivially match to reference.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(refPix.swizzle(1, 2, 3) - resPix.swizzle(1, 2, 3)),
                                                 nonShadowThreshold)))
            {
                errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                numFailed += 1;
                continue;
            }

            // Reference result is known to be a valid result, we can
            // skip verification if thes results are equal
            if (resPix.x() != refPix.x())
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
                const float triWx = triNdx ? dstW - wx : wx;
                const float triWy = triNdx ? dstH - wy : wy;
                const float triNx = triNdx ? 1.0f - nx : nx;
                const float triNy = triNdx ? 1.0f - ny : ny;

                const float coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy));
                const float coordDx = triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy) * srcSize;

                tcu::Vec2 lodBounds = tcu::computeLodBoundsFromDerivates(coordDx, coordDx, lodPrec);

                // Compute lod bounds across lodOffsets range.
                for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                {
                    const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                    const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                    const float nxo = wxo / dstW;
                    const float nyo = wyo / dstH;

                    const float coordDxo = triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo) * srcSize;
                    const float coordDyo = triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo) * srcSize;
                    const tcu::Vec2 lodO = tcu::computeLodBoundsFromDerivates(coordDxo, coordDyo, lodPrec);

                    lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                    lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                }

                const tcu::Vec2 clampedLod = tcu::clampLodBounds(
                    lodBounds + lodBias, tcu::Vec2(sampleParams.minLod, sampleParams.maxLod), lodPrec);
                const bool isOk = tcu::isTexCompareResultValid(src, sampleParams.sampler, comparePrec, tcu::Vec1(coord),
                                                               clampedLod, sampleParams.ref, resPix.x());

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

int computeTextureCompareDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                              const tcu::PixelBufferAccess &errorMask, const tcu::Texture1DArrayView &src,
                              const float *texCoord, const ReferenceParams &sampleParams,
                              const tcu::TexComparePrecision &comparePrec, const tcu::LodPrecision &lodPrec,
                              const tcu::Vec3 &nonShadowThreshold)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());
    DE_ASSERT(result.getHeight() == 1);

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[2 + 0], texCoord[4 + 0], texCoord[6 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[2 + 1], texCoord[4 + 1], texCoord[6 + 1]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), 1);
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const float srcSize      = float(src.getWidth());

    // Coordinates and lod per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    const int py = 0;
    {
        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = result.getPixel(px, py);
            const tcu::Vec4 refPix = reference.getPixel(px, py);

            // Other channels should trivially match to reference.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(refPix.swizzle(1, 2, 3) - resPix.swizzle(1, 2, 3)),
                                                 nonShadowThreshold)))
            {
                errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                numFailed += 1;
                continue;
            }

            // Reference result is known to be a valid result, we can
            // skip verification if these results are equal
            if (resPix.x() != refPix.x())
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
                const float triWx = triNdx ? dstW - wx : wx;
                const float triWy = triNdx ? dstH - wy : wy;
                const float triNx = triNdx ? 1.0f - nx : nx;
                const float triNy = triNdx ? 1.0f - ny : ny;

                const tcu::Vec2 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy));
                const float coordDx = triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy) * srcSize;

                tcu::Vec2 lodBounds = tcu::computeLodBoundsFromDerivates(coordDx, coordDx, lodPrec);

                // Compute lod bounds across lodOffsets range.
                for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                {
                    const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                    const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                    const float nxo = wxo / dstW;
                    const float nyo = wyo / dstH;

                    const float coordDxo = triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo) * srcSize;
                    const float coordDyo = triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo) * srcSize;
                    const tcu::Vec2 lodO = tcu::computeLodBoundsFromDerivates(coordDxo, coordDyo, lodPrec);

                    lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                    lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                }

                const tcu::Vec2 clampedLod = tcu::clampLodBounds(
                    lodBounds + lodBias, tcu::Vec2(sampleParams.minLod, sampleParams.maxLod), lodPrec);
                const bool isOk = tcu::isTexCompareResultValid(src, sampleParams.sampler, comparePrec, coord,
                                                               clampedLod, sampleParams.ref, resPix.x());

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

int computeTextureCompareDiff(const tcu::ConstPixelBufferAccess &result, const tcu::ConstPixelBufferAccess &reference,
                              const tcu::PixelBufferAccess &errorMask, const tcu::TextureCubeArrayView &src,
                              const float *texCoord, const ReferenceParams &sampleParams,
                              const tcu::TexComparePrecision &comparePrec, const tcu::LodPrecision &lodPrec,
                              const tcu::Vec3 &nonShadowThreshold)
{
    DE_ASSERT(result.getWidth() == reference.getWidth() && result.getHeight() == reference.getHeight());
    DE_ASSERT(result.getWidth() == errorMask.getWidth() && result.getHeight() == errorMask.getHeight());

    const tcu::Vec4 sq = tcu::Vec4(texCoord[0 + 0], texCoord[4 + 0], texCoord[8 + 0], texCoord[12 + 0]);
    const tcu::Vec4 tq = tcu::Vec4(texCoord[0 + 1], texCoord[4 + 1], texCoord[8 + 1], texCoord[12 + 1]);
    const tcu::Vec4 rq = tcu::Vec4(texCoord[0 + 2], texCoord[4 + 2], texCoord[8 + 2], texCoord[12 + 2]);
    const tcu::Vec4 qq = tcu::Vec4(texCoord[0 + 3], texCoord[4 + 3], texCoord[8 + 3], texCoord[12 + 3]);

    const tcu::IVec2 dstSize = tcu::IVec2(result.getWidth(), result.getHeight());
    const float dstW         = float(dstSize.x());
    const float dstH         = float(dstSize.y());
    const int srcSize        = src.getSize();

    // Coordinates per triangle.
    const tcu::Vec3 triS[2] = {sq.swizzle(0, 1, 2), sq.swizzle(3, 2, 1)};
    const tcu::Vec3 triT[2] = {tq.swizzle(0, 1, 2), tq.swizzle(3, 2, 1)};
    const tcu::Vec3 triR[2] = {rq.swizzle(0, 1, 2), rq.swizzle(3, 2, 1)};
    const tcu::Vec3 triQ[2] = {qq.swizzle(0, 1, 2), qq.swizzle(3, 2, 1)};
    const tcu::Vec3 triW[2] = {sampleParams.w.swizzle(0, 1, 2), sampleParams.w.swizzle(3, 2, 1)};

    const tcu::Vec2 lodBias((sampleParams.flags & ReferenceParams::USE_BIAS) ? sampleParams.bias : 0.0f);

    int numFailed = 0;

    const tcu::Vec2 lodOffsets[] = {
        tcu::Vec2(-1, 0),
        tcu::Vec2(+1, 0),
        tcu::Vec2(0, -1),
        tcu::Vec2(0, +1),
    };

    tcu::clear(errorMask, tcu::RGBA::green().toVec());

    for (int py = 0; py < result.getHeight(); py++)
    {
        for (int px = 0; px < result.getWidth(); px++)
        {
            const tcu::Vec4 resPix = result.getPixel(px, py);
            const tcu::Vec4 refPix = reference.getPixel(px, py);

            // Other channels should trivially match to reference.
            if (!tcu::boolAll(tcu::lessThanEqual(tcu::abs(refPix.swizzle(1, 2, 3) - resPix.swizzle(1, 2, 3)),
                                                 nonShadowThreshold)))
            {
                errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                numFailed += 1;
                continue;
            }

            // Reference result is known to be a valid result, we can
            // skip verification if thes results are equal
            if (resPix.x() != refPix.x())
            {
                const float wx = (float)px + 0.5f;
                const float wy = (float)py + 0.5f;
                const float nx = wx / dstW;
                const float ny = wy / dstH;

                const int triNdx  = nx + ny >= 1.0f ? 1 : 0;
                const float triWx = triNdx ? dstW - wx : wx;
                const float triWy = triNdx ? dstH - wy : wy;
                const float triNx = triNdx ? 1.0f - nx : nx;
                const float triNy = triNdx ? 1.0f - ny : ny;

                const tcu::Vec4 coord(projectedTriInterpolate(triS[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triT[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triR[triNdx], triW[triNdx], triNx, triNy),
                                      projectedTriInterpolate(triQ[triNdx], triW[triNdx], triNx, triNy));
                const tcu::Vec3 coordDx(triDerivateX(triS[triNdx], triW[triNdx], wx, dstW, triNy),
                                        triDerivateX(triT[triNdx], triW[triNdx], wx, dstW, triNy),
                                        triDerivateX(triR[triNdx], triW[triNdx], wx, dstW, triNy));
                const tcu::Vec3 coordDy(triDerivateY(triS[triNdx], triW[triNdx], wy, dstH, triNx),
                                        triDerivateY(triT[triNdx], triW[triNdx], wy, dstH, triNx),
                                        triDerivateY(triR[triNdx], triW[triNdx], wy, dstH, triNx));

                tcu::Vec2 lodBounds =
                    tcu::computeCubeLodBoundsFromDerivates(coord.swizzle(0, 1, 2), coordDx, coordDy, srcSize, lodPrec);

                // Compute lod bounds across lodOffsets range.
                for (int lodOffsNdx = 0; lodOffsNdx < DE_LENGTH_OF_ARRAY(lodOffsets); lodOffsNdx++)
                {
                    const float wxo = triWx + lodOffsets[lodOffsNdx].x();
                    const float wyo = triWy + lodOffsets[lodOffsNdx].y();
                    const float nxo = wxo / dstW;
                    const float nyo = wyo / dstH;

                    const tcu::Vec3 coordO(projectedTriInterpolate(triS[triNdx], triW[triNdx], nxo, nyo),
                                           projectedTriInterpolate(triT[triNdx], triW[triNdx], nxo, nyo),
                                           projectedTriInterpolate(triR[triNdx], triW[triNdx], nxo, nyo));
                    const tcu::Vec3 coordDxo(triDerivateX(triS[triNdx], triW[triNdx], wxo, dstW, nyo),
                                             triDerivateX(triT[triNdx], triW[triNdx], wxo, dstW, nyo),
                                             triDerivateX(triR[triNdx], triW[triNdx], wxo, dstW, nyo));
                    const tcu::Vec3 coordDyo(triDerivateY(triS[triNdx], triW[triNdx], wyo, dstH, nxo),
                                             triDerivateY(triT[triNdx], triW[triNdx], wyo, dstH, nxo),
                                             triDerivateY(triR[triNdx], triW[triNdx], wyo, dstH, nxo));
                    const tcu::Vec2 lodO =
                        tcu::computeCubeLodBoundsFromDerivates(coordO, coordDxo, coordDyo, srcSize, lodPrec);

                    lodBounds.x() = de::min(lodBounds.x(), lodO.x());
                    lodBounds.y() = de::max(lodBounds.y(), lodO.y());
                }

                const tcu::Vec2 clampedLod = tcu::clampLodBounds(
                    lodBounds + lodBias, tcu::Vec2(sampleParams.minLod, sampleParams.maxLod), lodPrec);
                const bool isOk = tcu::isTexCompareResultValid(src, sampleParams.sampler, comparePrec, coord,
                                                               clampedLod, sampleParams.ref, resPix.x());

                if (!isOk)
                {
                    errorMask.setPixel(tcu::RGBA::red().toVec(), px, py);
                    numFailed += 1;
                }
            }
        }
    }

    return numFailed;
}

// Mipmap generation comparison.

static int compareGenMipmapBilinear(const tcu::ConstPixelBufferAccess &dst, const tcu::ConstPixelBufferAccess &src,
                                    const tcu::PixelBufferAccess &errorMask, const GenMipmapPrecision &precision)
{
    DE_ASSERT(dst.getDepth() == 1 && src.getDepth() == 1); // \todo [2013-10-29 pyry] 3D textures.

    const float dstW = float(dst.getWidth());
    const float dstH = float(dst.getHeight());
    const float srcW = float(src.getWidth());
    const float srcH = float(src.getHeight());
    int numFailed    = 0;

    // Translation to lookup verification parameters.
    const tcu::Sampler sampler(tcu::Sampler::CLAMP_TO_EDGE, tcu::Sampler::CLAMP_TO_EDGE, tcu::Sampler::CLAMP_TO_EDGE,
                               tcu::Sampler::LINEAR, tcu::Sampler::LINEAR, 0.0f, false /* non-normalized coords */);
    tcu::LookupPrecision lookupPrec;

    lookupPrec.colorThreshold = precision.colorThreshold;
    lookupPrec.colorMask      = precision.colorMask;
    lookupPrec.coordBits      = tcu::IVec3(22);
    lookupPrec.uvwBits        = precision.filterBits;

    for (int y = 0; y < dst.getHeight(); y++)
        for (int x = 0; x < dst.getWidth(); x++)
        {
            const tcu::Vec4 result = dst.getPixel(x, y);
            const float cx         = (float(x) + 0.5f) / dstW * srcW;
            const float cy         = (float(y) + 0.5f) / dstH * srcH;
            const bool isOk = tcu::isLinearSampleResultValid(src, sampler, lookupPrec, tcu::Vec2(cx, cy), 0, result);

            errorMask.setPixel(isOk ? tcu::RGBA::green().toVec() : tcu::RGBA::red().toVec(), x, y);
            if (!isOk)
                numFailed += 1;
        }

    return numFailed;
}

static int compareGenMipmapBox(const tcu::ConstPixelBufferAccess &dst, const tcu::ConstPixelBufferAccess &src,
                               const tcu::PixelBufferAccess &errorMask, const GenMipmapPrecision &precision)
{
    DE_ASSERT(dst.getDepth() == 1 && src.getDepth() == 1); // \todo [2013-10-29 pyry] 3D textures.

    const float dstW = float(dst.getWidth());
    const float dstH = float(dst.getHeight());
    const float srcW = float(src.getWidth());
    const float srcH = float(src.getHeight());
    int numFailed    = 0;

    // Translation to lookup verification parameters.
    const tcu::Sampler sampler(tcu::Sampler::CLAMP_TO_EDGE, tcu::Sampler::CLAMP_TO_EDGE, tcu::Sampler::CLAMP_TO_EDGE,
                               tcu::Sampler::LINEAR, tcu::Sampler::LINEAR, 0.0f, false /* non-normalized coords */);
    tcu::LookupPrecision lookupPrec;

    lookupPrec.colorThreshold = precision.colorThreshold;
    lookupPrec.colorMask      = precision.colorMask;
    lookupPrec.coordBits      = tcu::IVec3(22);
    lookupPrec.uvwBits        = precision.filterBits;

    for (int y = 0; y < dst.getHeight(); y++)
        for (int x = 0; x < dst.getWidth(); x++)
        {
            const tcu::Vec4 result = dst.getPixel(x, y);
            const float cx         = deFloatFloor(float(x) / dstW * srcW) + 1.0f;
            const float cy         = deFloatFloor(float(y) / dstH * srcH) + 1.0f;
            const bool isOk = tcu::isLinearSampleResultValid(src, sampler, lookupPrec, tcu::Vec2(cx, cy), 0, result);

            errorMask.setPixel(isOk ? tcu::RGBA::green().toVec() : tcu::RGBA::red().toVec(), x, y);
            if (!isOk)
                numFailed += 1;
        }

    return numFailed;
}

static int compareGenMipmapVeryLenient(const tcu::ConstPixelBufferAccess &dst, const tcu::ConstPixelBufferAccess &src,
                                       const tcu::PixelBufferAccess &errorMask, const GenMipmapPrecision &precision)
{
    DE_ASSERT(dst.getDepth() == 1 && src.getDepth() == 1); // \todo [2013-10-29 pyry] 3D textures.
    DE_UNREF(precision);

    const float dstW = float(dst.getWidth());
    const float dstH = float(dst.getHeight());
    const float srcW = float(src.getWidth());
    const float srcH = float(src.getHeight());
    int numFailed    = 0;

    for (int y = 0; y < dst.getHeight(); y++)
        for (int x = 0; x < dst.getWidth(); x++)
        {
            const tcu::Vec4 result = dst.getPixel(x, y);
            const int minX         = deFloorFloatToInt32(((float)x - 0.5f) / dstW * srcW);
            const int minY         = deFloorFloatToInt32(((float)y - 0.5f) / dstH * srcH);
            const int maxX         = deCeilFloatToInt32(((float)x + 1.5f) / dstW * srcW);
            const int maxY         = deCeilFloatToInt32(((float)y + 1.5f) / dstH * srcH);
            tcu::Vec4 minVal, maxVal;
            bool isOk;

            DE_ASSERT(minX < maxX && minY < maxY);

            for (int ky = minY; ky <= maxY; ky++)
            {
                for (int kx = minX; kx <= maxX; kx++)
                {
                    const int sx           = de::clamp(kx, 0, src.getWidth() - 1);
                    const int sy           = de::clamp(ky, 0, src.getHeight() - 1);
                    const tcu::Vec4 sample = src.getPixel(sx, sy);

                    if (ky == minY && kx == minX)
                    {
                        minVal = sample;
                        maxVal = sample;
                    }
                    else
                    {
                        minVal = min(sample, minVal);
                        maxVal = max(sample, maxVal);
                    }
                }
            }

            isOk = boolAll(logicalAnd(lessThanEqual(minVal, result), lessThanEqual(result, maxVal)));

            errorMask.setPixel(isOk ? tcu::RGBA::green().toVec() : tcu::RGBA::red().toVec(), x, y);
            if (!isOk)
                numFailed += 1;
        }

    return numFailed;
}

qpTestResult compareGenMipmapResult(tcu::TestLog &log, const tcu::Texture2D &resultTexture,
                                    const tcu::Texture2D &level0Reference, const GenMipmapPrecision &precision)
{
    qpTestResult result = QP_TEST_RESULT_PASS;

    // Special comparison for level 0.
    {
        const tcu::Vec4 threshold = select(precision.colorThreshold, tcu::Vec4(1.0f), precision.colorMask);
        const bool level0Ok       = tcu::floatThresholdCompare(log, "Level0", "Level 0", level0Reference.getLevel(0),
                                                               resultTexture.getLevel(0), threshold, tcu::COMPARE_LOG_RESULT);

        if (!level0Ok)
        {
            log << tcu::TestLog::Message << "ERROR: Level 0 comparison failed!" << tcu::TestLog::EndMessage;
            result = QP_TEST_RESULT_FAIL;
        }
    }

    for (int levelNdx = 1; levelNdx < resultTexture.getNumLevels(); levelNdx++)
    {
        const tcu::ConstPixelBufferAccess src = resultTexture.getLevel(levelNdx - 1);
        const tcu::ConstPixelBufferAccess dst = resultTexture.getLevel(levelNdx);
        tcu::Surface errorMask(dst.getWidth(), dst.getHeight());
        bool levelOk = false;

        // Try different comparisons in quality order.

        if (!levelOk)
        {
            const int numFailed = compareGenMipmapBilinear(dst, src, errorMask.getAccess(), precision);
            if (numFailed == 0)
                levelOk = true;
            else
                log << tcu::TestLog::Message << "WARNING: Level " << levelNdx
                    << " comparison to bilinear method failed, found " << numFailed << " invalid pixels."
                    << tcu::TestLog::EndMessage;
        }

        if (!levelOk)
        {
            const int numFailed = compareGenMipmapBox(dst, src, errorMask.getAccess(), precision);
            if (numFailed == 0)
                levelOk = true;
            else
                log << tcu::TestLog::Message << "WARNING: Level " << levelNdx
                    << " comparison to box method failed, found " << numFailed << " invalid pixels."
                    << tcu::TestLog::EndMessage;
        }

        // At this point all high-quality methods have been used.
        if (!levelOk && result == QP_TEST_RESULT_PASS)
            result = QP_TEST_RESULT_QUALITY_WARNING;

        if (!levelOk)
        {
            const int numFailed = compareGenMipmapVeryLenient(dst, src, errorMask.getAccess(), precision);
            if (numFailed == 0)
                levelOk = true;
            else
                log << tcu::TestLog::Message << "ERROR: Level " << levelNdx << " appears to contain " << numFailed
                    << " completely wrong pixels, failing case!" << tcu::TestLog::EndMessage;
        }

        if (!levelOk)
            result = QP_TEST_RESULT_FAIL;

        log << tcu::TestLog::ImageSet(string("Level") + de::toString(levelNdx),
                                      string("Level ") + de::toString(levelNdx) + " result")
            << tcu::TestLog::Image("Result", "Result", dst);

        if (!levelOk)
            log << tcu::TestLog::Image("ErrorMask", "Error mask", errorMask);

        log << tcu::TestLog::EndImageSet;
    }

    return result;
}

qpTestResult compareGenMipmapResult(tcu::TestLog &log, const tcu::TextureCube &resultTexture,
                                    const tcu::TextureCube &level0Reference, const GenMipmapPrecision &precision)
{
    qpTestResult result = QP_TEST_RESULT_PASS;

    static const char *s_faceNames[] = {"-X", "+X", "-Y", "+Y", "-Z", "+Z"};
    DE_STATIC_ASSERT(DE_LENGTH_OF_ARRAY(s_faceNames) == tcu::CUBEFACE_LAST);

    // Special comparison for level 0.
    for (int faceNdx = 0; faceNdx < tcu::CUBEFACE_LAST; faceNdx++)
    {
        const tcu::CubeFace face  = tcu::CubeFace(faceNdx);
        const tcu::Vec4 threshold = select(precision.colorThreshold, tcu::Vec4(1.0f), precision.colorMask);
        const bool level0Ok       = tcu::floatThresholdCompare(
            log, ("Level0Face" + de::toString(faceNdx)).c_str(), (string("Level 0, face ") + s_faceNames[face]).c_str(),
            level0Reference.getLevelFace(0, face), resultTexture.getLevelFace(0, face), threshold,
            tcu::COMPARE_LOG_RESULT);

        if (!level0Ok)
        {
            log << tcu::TestLog::Message << "ERROR: Level 0, face " << s_faceNames[face] << " comparison failed!"
                << tcu::TestLog::EndMessage;
            result = QP_TEST_RESULT_FAIL;
        }
    }

    for (int levelNdx = 1; levelNdx < resultTexture.getNumLevels(); levelNdx++)
    {
        for (int faceNdx = 0; faceNdx < tcu::CUBEFACE_LAST; faceNdx++)
        {
            const tcu::CubeFace face              = tcu::CubeFace(faceNdx);
            const char *faceName                  = s_faceNames[face];
            const tcu::ConstPixelBufferAccess src = resultTexture.getLevelFace(levelNdx - 1, face);
            const tcu::ConstPixelBufferAccess dst = resultTexture.getLevelFace(levelNdx, face);
            tcu::Surface errorMask(dst.getWidth(), dst.getHeight());
            bool levelOk = false;

            // Try different comparisons in quality order.

            if (!levelOk)
            {
                const int numFailed = compareGenMipmapBilinear(dst, src, errorMask.getAccess(), precision);
                if (numFailed == 0)
                    levelOk = true;
                else
                    log << tcu::TestLog::Message << "WARNING: Level " << levelNdx << ", face " << faceName
                        << " comparison to bilinear method failed, found " << numFailed << " invalid pixels."
                        << tcu::TestLog::EndMessage;
            }

            if (!levelOk)
            {
                const int numFailed = compareGenMipmapBox(dst, src, errorMask.getAccess(), precision);
                if (numFailed == 0)
                    levelOk = true;
                else
                    log << tcu::TestLog::Message << "WARNING: Level " << levelNdx << ", face " << faceName
                        << " comparison to box method failed, found " << numFailed << " invalid pixels."
                        << tcu::TestLog::EndMessage;
            }

            // At this point all high-quality methods have been used.
            if (!levelOk && result == QP_TEST_RESULT_PASS)
                result = QP_TEST_RESULT_QUALITY_WARNING;

            if (!levelOk)
            {
                const int numFailed = compareGenMipmapVeryLenient(dst, src, errorMask.getAccess(), precision);
                if (numFailed == 0)
                    levelOk = true;
                else
                    log << tcu::TestLog::Message << "ERROR: Level " << levelNdx << ", face " << faceName
                        << " appears to contain " << numFailed << " completely wrong pixels, failing case!"
                        << tcu::TestLog::EndMessage;
            }

            if (!levelOk)
                result = QP_TEST_RESULT_FAIL;

            log << tcu::TestLog::ImageSet(string("Level") + de::toString(levelNdx) + "Face" + de::toString(faceNdx),
                                          string("Level ") + de::toString(levelNdx) + ", face " + string(faceName) +
                                              " result")
                << tcu::TestLog::Image("Result", "Result", dst);

            if (!levelOk)
                log << tcu::TestLog::Image("ErrorMask", "Error mask", errorMask);

            log << tcu::TestLog::EndImageSet;
        }
    }

    return result;
}

// Logging utilities.

std::ostream &operator<<(std::ostream &str, const LogGradientFmt &fmt)
{
    return str << "(R: " << fmt.valueMin->x() << " -> " << fmt.valueMax->x() << ", "
               << "G: " << fmt.valueMin->y() << " -> " << fmt.valueMax->y() << ", "
               << "B: " << fmt.valueMin->z() << " -> " << fmt.valueMax->z() << ", "
               << "A: " << fmt.valueMin->w() << " -> " << fmt.valueMax->w() << ")";
}

} // namespace TextureTestUtil
} // namespace glu