render/vulkan: experiment with compute shaders

[emersion]

This is closer to bare metal so should be faster. On some GPUs (AMD) we could also use the compute queue and leave the graphics queue for 3D rendering (e.g. resource-intensive games).

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wlroots has migrated to gitlab.freedesktop.org. This issue has been moved to:

https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3265

[alyssarosenzweig]

This is closer to bare metal so should be faster

Depends a lot on the hardware and workload. On Mali, for example, imageStore in a CS can be slower than outputting a colour via a fragment shader, since the latter supports framebuffer compression but the former does not.

[emersion]

Yeah, @Joshua-Ashton said that we won't want to unconditionally use compute shaders, we'd only want to do so if the Vulkan driver can write to non-linear images from them.

[Joshua-Ashton]

And its actually a win compared to gfx. Thats why we should have both and pick appropriately.