What is the difference between framebuffer and image in Vulkan?

  • VkFramebuffer + VkRenderPass defines the render target.

  • Render pass defines which attachment will be written with colors.

  • VkFramebuffer defines which VkImageView is to be which attachment.

  • VkImageView defines which part of VkImage to use.

  • VkImage defines which VkDeviceMemory is used and a format of the texel.

Or maybe in opposite sequence:

  • VkDeviceMemory is just a sequence of N bytes in memory.

  • VkImage object adds to it e.g. information about the format (so you can address by texels, not bytes).

  • VkImageView object helps select only part (array or mip) of the VkImage (like stringView, arrayView or whathaveyou does). Also can help to match to some incompatible interface (by type casting format).

  • VkFramebuffer binds a VkImageView with an attachment.

  • VkRenderpass defines which attachment will be drawn into

So it’s not like you do not use an image. You do, through the Vulkan Framebuffer.

Swapchain image is no different from any other image. Except that the driver is the owner of the image. You can’t destroy it directly or allocate it yourself. You just borrow it from the driver for the duration between acquire and present operation.

There’s (usually) more of the swapchain images for the purposes of buffering and advance rendering. AFAIK you would need a separate VkFramebuffer for each image (which is annoying, but more in tune with what actually happens underneath).

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