DXVK Already Lands Vulkan Transform Feedback Support, RADV Posts Patches

With the newly-announced Vulkan 1.1.88 that brings VK_EXT_transform_feedback, the DXVK Direct3D-on-Vulkan layer has already implemented the transform feedback support.

DXVK developer Philip Rebohle working under contract for Valve has already merged his transform feedback implementation into the mainline code-base. He didn't magically write all of the necessary code for Direct3D 11 stream outputs mapped to Vulkan and the like today, but had written it in advance -- presumably thanks to Valve's involvement with the Vulkan working group. This is good news as working out the DXVK transform feedback support prior to firming up the VK_EXT_transform_feedback extension ensured that this new extension would work out for DXVK's needs.

As covered in the earlier Vulkan 1.1.88 article, VK_EXT_transform_feedback will also be relevant to projects like ANGLE and VKD3D though as of writing we haven't seen any patches on those fronts. Besides Direct3D, this can also help the various efforts working to get OpenGL running atop Vulkan. The DXVK support was merged with this commit for dealing with this extension that mimics OpenGL's transform feedback functionality.

Before getting too excited about the prospects of more Direct3D functionality working now with DXVK, keep in mind your GPU Vulkan driver needs to support this extension... As of writing I have only seen patches surface for RADV.

Valve's Samuel Pitoiset posted 15 patches amounting to just under two thousand lines of new code for getting this Radeon Vulkan driver supporting VK_EXT_transform_feedback. Samuel confirmed he's already been testing it "a lot" with DXVK and RenderDoc. This support still should be merged in plenty of time for Mesa 18.3 due out as stable by year's end.