| Summary: | Result of rendering to a texture via a framebuffer is not always ready in time | ||
|---|---|---|---|
| Product: | Mesa | Reporter: | Neil Roberts <nroberts> |
| Component: | Drivers/DRI/i965 | Assignee: | Eric Anholt <eric> |
| Status: | RESOLVED FIXED | QA Contact: | |
| Severity: | major | ||
| Priority: | high | ||
| Version: | unspecified | ||
| Hardware: | Other | ||
| OS: | All | ||
| Whiteboard: | |||
| i915 platform: | i915 features: | ||
| Attachments: | Test case | ||
commit 16bdf593f549d3c6e0a987ad640a750024fc77ad Author: Eric Anholt <eric@anholt.net> Date: Wed Dec 9 11:36:45 2009 -0800 intel: Flush the render/texture cache when finishing render to texture. Back when we were flushing the entire batch at BindFramebuffer, the kernel would notice the domain transition when someone went to texture from it and flush for us. We no longer do the batch flushing every time, so we get to do aggressive flushing until we move batchbuffer handling to libdrm. Fixes piglit fbo-flushing. Bug #25377. No noticeable performance loss on cairo-gl (so this is better than batch flushing). sorry, failed at pushing. new commit name: commit 539a14a1dd5a0d277b193d9cd2d06423ed98dc8a Author: Eric Anholt <eric@anholt.net> Date: Wed Dec 9 11:36:45 2009 -0800 intel: Flush the render/texture cache when finishing render to texture. |
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Created attachment 31624 [details] Test case If you render to a texture using the GL_ARB_framebuffer_object extension and then render something else using that texture immediately then the contents is not always updated in time and some artefacts show. I think this is the cause of a breakage in tests/conform/test-texture-fbo in Clutter The attached test case also shows the problem. It renders a red square to one texture and then renders a chain of 15 more FBOs. The texture from the previous FBO is rendered to each subsequent FBO. If I run this on my i965 with Mesa-7.7 devel then some of the squares are different heights and there is flickering as if sometimes the top pixels are not rendered yet. If I run with LIBGL_ALWAYS_SOFTWARE then the bug goes away. Or I can put a glFinish after rendering each FBO and this also fixes the problem. There is a '#if 0' in the test to demonstrate this.