Follow-up: In further testing, I did get some races with my test
condition, and it turns out that in OpenGL and Vulkan, unlike in
Direct3D, gl_SampleMaskIn contains only 1 sample when sample shading is
used. So there's even less possible meaningful usage of pixel interlock
with sample shading, maybe only with very tiny primitives covering only
1 sample, or with all samples but one masked out via the fixed-function
sample mask (which is exposed in Vulkan directly, but in OpenGL, only as
a fraction via glSampleCoverage).
- [Piglit] [Bug] Fragment shader interlock sample shading test... Triang3l
- Re: [Piglit] [Bug] Fragment shader interlock sample sha... Triang3l