Method CreateStaging

GTE/Graphics/GL46/GL46TextureSingle.cpp:288–340

}

void GL46TextureSingle::CreateStaging()
{
    auto texture = GetTexture();
    auto const copyType = texture->GetCopy();

    auto const createPixelUnpackBuffers = 
        (copyType == Resource::Copy::CPU_TO_STAGING) ||
        (copyType == Resource::Copy::BIDIRECTIONAL);

    auto const createPixelPackBuffers =
        (copyType == Resource::Copy::STAGING_TO_CPU) ||
        (copyType == Resource::Copy::BIDIRECTIONAL);

    // TODO:  Determine frequency and nature of usage for this staging buffer
    // when created by calling glBufferData.
    GLenum usage = GL_DYNAMIC_DRAW;

    if (createPixelUnpackBuffers)
    {
        for (int32_t level = 0; level < mNumLevels; ++level)
        {
            auto& pixBuffer = mLevelPixelUnpackBuffer[level];
            if (0 == pixBuffer)
            {
                auto numBytes = texture->GetNumBytesFor(level);

                // Create pixel buffer for staging.
                glGenBuffers(1, &pixBuffer);
                glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pixBuffer);
                glBufferData(GL_PIXEL_UNPACK_BUFFER, numBytes, 0, usage);
                glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
            }
        }
    }

    if (createPixelPackBuffers)
    {
        for (int32_t level = 0; level < mNumLevels; ++level)
        {
            auto& pixBuffer = mLevelPixelPackBuffer[level];
            if (0 == pixBuffer)
            {
                auto numBytes = texture->GetNumBytesFor(level);

                // Create pixel buffer for staging.
                glGenBuffers(1, &pixBuffer);
                glBindBuffer(GL_PIXEL_PACK_BUFFER, pixBuffer);
                glBufferData(GL_PIXEL_PACK_BUFFER, numBytes, 0, usage);
                glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
            }
        }
    }
}