Function ValidateImageTexture

tests/gpu/GPUUnitTest.cpp:388–526

Validate the GPU processing against the CPU one.

    // Validate the GPU processing against the CPU one.
    void ValidateImageTexture(OCIO::OglAppRcPtr & app, OCIOGPUTestRcPtr & test)
    {
        // Each retest is rebuilding a cpu proc.
        OCIO::ConstCPUProcessorRcPtr processor = test->getProcessor()->getDefaultCPUProcessor();

        const float epsilon = test->getErrorThreshold();
        const float expectMinValue = test->getExpectedMinimalValue();

        // Compute the width & height to avoid testing the padded values.

        const size_t numPixels = test->getCustomValues().m_originalInputValueSize / g_components;

        size_t width, height = 0;
        if(numPixels<=g_winWidth)
        {
            width  = numPixels;
            height = 1;
        }
        else
        {
            width  = g_winWidth;
            height = numPixels/g_winWidth;
            if((numPixels%g_winWidth)>0) height += 1;
        }

        if(width==0 || width>g_winWidth || height==0 || height>g_winHeight)
        {
            throw OCIO::Exception("Mismatch with the expected image size");
        }

        // Step 1: Compute the output using the CPU engine.

        OCIOGPUTest::CustomValues::Values cpuImage = test->getCustomValues().m_inputValues;
        OCIO::PackedImageDesc desc(&cpuImage[0], (long)width, (long)height, g_components);
        processor->apply(desc);

        // Step 2: Grab the GPU output from the rendering buffer.

        OCIOGPUTest::CustomValues::Values gpuImage(g_winWidth*g_winHeight*g_components, 0.0f);
        app->readImage(&gpuImage[0]);

        // Step 3: Compare the two results.

        const OCIOGPUTest::CustomValues::Values & image = test->getCustomValues().m_inputValues;
        float diff = 0.0f;
        // Initialize these to a known reference value, if any of the four component checks
        // below fail, it will be set to the index of the last failure. Only the last failure
        // is printed below.
        size_t idxDiff = invalidIndex;
        size_t idxNan = invalidIndex;
        size_t idxInf = invalidIndex;
        constexpr float huge = std::numeric_limits<float>::max();
        float minVals[4] = {huge, huge, huge, huge};
        float maxVals[4] = {-huge, -huge, -huge, -huge};
        const bool relativeTest = test->getRelativeComparison();
        for(size_t idx=0; idx<(width*height); ++idx)
        {
            for(size_t chan=0; chan<4; ++chan)