Function VulkanReadPixels

engine/graphics/src/vulkan/graphics_vulkan.cpp:5391–5478

    }

    static void VulkanReadPixels(HContext _context, int32_t x, int32_t y, uint32_t width, uint32_t height, void* buffer, uint32_t buffer_size)
    {
        VulkanContext* context = (VulkanContext*) _context;

        assert (buffer_size >= width * height * 4);

        HRenderTarget currentt_rt_h = context->m_CurrentRenderTarget;
        bool in_render_pass = IsRenderTargetbound(context, currentt_rt_h);

        // We can't copy an image if we are inside a render pass.
        // This is considered an expensive operation, but unless we have user facing functionality to begin/end render passes,
        // this is as good as it gets currently.
        if (in_render_pass)
        {
            EndRenderPass(context);
        }

        // Create a temporary stage buffer that we can map to
        DeviceBuffer stage_buffer(VK_IMAGE_USAGE_TRANSFER_DST_BIT);
        VkResult res = CreateDeviceBuffer(context->m_PhysicalDevice.m_Device, context->m_LogicalDevice.m_Device, buffer_size,
            VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, &stage_buffer);
        CHECK_VK_ERROR(res);

        // Keep the readback in a single temporary command buffer so the swapchain image is restored
        // to its presentable layout before any later main render pass rebind or final present.

        VkCommandBuffer vk_command_buffer = BeginSingleTimeCommands(context->m_LogicalDevice.m_Device, context->m_LogicalDevice.m_CommandPool);

        DM_MUTEX_SCOPED_LOCK(context->m_BaseContext.m_AssetHandleContainerMutex);
        VulkanTexture* tex_sc = GetAssetFromContainer<VulkanTexture>(context->m_BaseContext.m_AssetHandleContainer, context->m_CurrentSwapchainTexture);

        TransitionImageLayoutWithCmdBuffer(
            vk_command_buffer,
            tex_sc,
            VK_IMAGE_ASPECT_COLOR_BIT,
            VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
            0,
            1);

        VkBufferImageCopy vk_copy_region = {};
        vk_copy_region.imageOffset.x               = x;
        vk_copy_region.imageOffset.y               = y;
        vk_copy_region.imageExtent.width           = width;
        vk_copy_region.imageExtent.height          = height;
        vk_copy_region.imageExtent.depth           = 1;
        vk_copy_region.imageSubresource.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
        vk_copy_region.imageSubresource.layerCount = 1;

        TouchResource(context, tex_sc);
        TouchResource(context, &stage_buffer);

        vkCmdCopyImageToBuffer(
            vk_command_buffer,
            context->m_SwapChain->Image(),
            VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
            stage_buffer.m_Handle.m_Buffer,
            1, &vk_copy_region);