Module wgpu_core::swap_chain

Swap chain management.

Lifecycle

At the low level, the swap chain is using the new simplified model of gfx-rs.

A swap chain is a separate object that is backend-dependent but shares the index with the parent surface, which is backend-independent. This ensures a 1:1 correspondence between them.

get_next_image() requests a new image from the surface. It becomes a part of TextureViewInner::SwapChain of the resulted view. The view is registered in the HUB but not in the device tracker.

The only operation allowed on the view is to be either a color or a resolve attachment. It can only be used in one command buffer, which needs to be submitted before presenting. Command buffer tracker knows about the view, but only for the duration of recording. The view ID is erased from it at the end, so that it's not merged into the device tracker.

When a swapchain view is used in begin_render_pass(), we assume the start and end image layouts purely based on whether or not this view was used in this command buffer before. It always starts with Uninitialized and ends with Present, so that no barriers are needed when we need to actually present it.

In queue_submit() we make sure to signal the semaphore whenever we render to a swap chain view.

In present() we return the swap chain image back and wait on the semaphore.

Structs

SwapChain
SwapChainOutput

Constants

DESIRED_NUM_FRAMES