Hello there,
I hope I’m posting in the right place.
We are facing an issue with our implementation of VRS on Vulkan API. Shading rate image seems bound in a sporadically manner betweens draw calls. It results as flickering image switching between one shading rate to another.
We are only rely on Shading Rate Image to alter the shading rate on screen space. The image (R8 format) is generated each frame and use during the next frame as an Shading Rate Attachment for all the involved drawcalls. We are using dynamic rendering in our engine.
With a RenderDoc capture, we can see that render states are correctly set in the pipeline. The VRS combiners are set to:
VK_FRAGMENT_SHADING_RATE_COMBINER_OP_MAX_KHR, VK_FRAGMENT_SHADING_RATE_COMBINER_OP_MAX_KHR
Pipeline shading rate is set to 1x1 and primitive does not emit any shading rate.
Barriers are correctly set: UAV for generating, then GENERAL when ending the frame and finally SHADING_RATE_ATTACHEMENT when beginning the frame for the next drawcalls.
We’ve tested on the latest Nvidia driver on a RTX 3070 (566.14). The issue does not appears on AMD GPU.
Hope those informations helps you.