| Summary: | gl_PrimitiveID is zero if no geometry shader is present | ||
|---|---|---|---|
| Product: | Mesa | Reporter: | pavol |
| Component: | Drivers/Gallium/r600 | Assignee: | Default DRI bug account <dri-devel> |
| Status: | RESOLVED FIXED | QA Contact: | |
| Severity: | normal | ||
| Priority: | highest | CC: | pavol |
| Version: | git | ||
| Hardware: | Other | ||
| OS: | All | ||
| Whiteboard: | |||
| i915 platform: | i915 features: | ||
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Description
pavol
2014-05-20 08:15:35 UTC
AFAICT the hardware doesn't provide any way to retrieve the primitive ID without a geometry shader, so we'd probably need to use a passthrough geometry shader for this. Any volunteers? Alright, I can create 3 geometry shaders for all primitives, but I am not sure if that is the right way for mesa. Thanks Just to be clear, I'm talking about doing this transparently in the driver, not in the application. I do not have radeonsi supported device. How does Intel driver support this? I think this is really useful for picking algorithm. (In reply to pavol from comment #4) > I do not have radeonsi supported device. How does Intel driver support this? > I think this is really useful for picking algorithm. The piglit test tests/spec/glsl-1.50/execution/primitive-id-no-gs.shader_test is for this very case. That test passes at least on my Ivybridge. I don't know what we do in the driver to make this work... or if the hardware just sorts it out. The hw GS mode A should be able to do this, which is basically a VS which gets PrimitiveID on the input. FYI I've posted patches to mesa-dev to address this for evergreen and later. fix for this pushed to mesa master Thank you, it works great. |
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