Method ReadTexture

deps/LLGL/sources/Renderer/Vulkan/VKRenderSystem.cpp:486–551

}

void VKRenderSystem::ReadTexture(Texture& texture, const TextureRegion& textureRegion, const DstImageDescriptor& imageDesc)
{
    auto& textureVK = LLGL_CAST(VKTexture&, texture);

    /* Determine size of image for staging buffer */
    const auto& offset = textureRegion.offset;
    const auto& extent = textureRegion.extent;
    const auto  format = VKTypes::Unmap(textureVK.GetVkFormat());

    auto        image           = textureVK.GetVkImage();
    const auto  imageSize       = extent.width * extent.height * extent.depth;
    const auto  imageDataSize   = static_cast<VkDeviceSize>(GetMemoryFootprint(format, imageSize));

    /* Create staging buffer */
    VkBufferCreateInfo stagingCreateInfo;
    BuildVkBufferCreateInfo(stagingCreateInfo, imageDataSize, VK_BUFFER_USAGE_TRANSFER_DST_BIT);
    auto stagingBuffer = CreateStagingBuffer(stagingCreateInfo);

    /* Copy staging buffer into hardware texture, then transfer image into sampling-ready state */
    auto cmdBuffer = device_.AllocCommandBuffer();
    {
        device_.TransitionImageLayout(
            cmdBuffer,
            image,
            textureVK.GetVkFormat(),
            VK_IMAGE_LAYOUT_UNDEFINED,
            VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
            textureRegion.subresource
        );

        device_.CopyImageToBuffer(
            cmdBuffer,
            image,
            stagingBuffer.GetVkBuffer(),
            VkOffset3D{ offset.x, offset.y, offset.z },
            VkExtent3D{ extent.width, extent.height, extent.depth },
            textureRegion.subresource
        );

        device_.TransitionImageLayout(
            cmdBuffer,
            image,
            textureVK.GetVkFormat(),
            VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
            VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL,
            textureRegion.subresource
        );
    }
    device_.FlushCommandBuffer(cmdBuffer);

    /* Map staging buffer to CPU memory space */
    if (auto region = stagingBuffer.GetMemoryRegion())
    {
        /* Map buffer memory to host memory */
        auto deviceMemory = region->GetParentChunk();
        if (auto memory = deviceMemory->Map(device_, region->GetOffset(), imageDataSize))
        {
            /* Copy data to buffer object */