I need copy image from SwapChainImage to RAM memory and do somethings on CPU with this image.
How do this ?
I don`t want render in texture. I want copy direct from SwapChainImage to RAM.
Its useful when i don’t know how rendering scene , or how write render another programmers team.
Presentation is a read-only operation that will not affect the content of the presentable images. Upon reacquiring the
image and transitioning it away from the VK_IMAGE_LAYOUT_PRESENT_SRC_KHR layout, the contents will be the
same as they were prior to transitioning the image to the present source layout and presenting it. However, if a
mechanism other than Vulkan is used to modify the platform window associated with the swapchain, the content of all
presentable images in the swapchain becomes undefined.
I.e. you can simply read the previous frame in case of double-buffering. However, that’s a VERY specific use-case I imagine. And things like Steam overlay will mess up whatever you want to do with your frame.
If VkSurfaceCapabilitiesKHR::supportedUsageFlags contains USAGE_TRANSFER you can copy it out to another host-accessible VkImage, do your thing with it and copy it back.