The Radeon R300 series turns 24 years old this year and thanks to the open-source ATI R300 Gallium3D driver that began via reverse engineering, it’s still continuing to see the occasional random fixes from the open-source community.
Independent open-source developer Pavel Ondračkar has managed to fix occlusion query support in the R300 driver for benefiting R300 through R500 class ATI GPUs. Pavel explained in a recent merge request that landed overnight in Mesa 26.1-devel:
“This is my attempt to fix the occlusion queries. There was a previous one by @mareko in 2012 which was however later reverted since it broke HyperZ. This approach should hopefully be much less invasive (the dummy z buffer is used only when there is active query), and the tests seem happy. I’ve done also some usual app testing: Unigine, Lightsmark, some wined3d and all seems fine, but more real-world testing would be appreciated OFC.”
For those still using the old R300 era graphics hardware, this fixed OpenGL occlusion queries support seems to work out well enough that the code is merged for next quarter’s Mesa 26.1 release.
Pavel is also working through some other R300 driver fixes like fixing HyperZ for large surfaces with that merge request still pending.
