Rewrite hardware occlusion query, Mesa 23.0 has incorporated the new raspberry pie V3DV Vulkan driver

CTOnews.com, November 26, the Broadcom V3DV VideoCore open source Vulkan driver in Mesa has rewritten hardware occlusion query (occlusion queries) related code, greatly improving performance and reliability.

Iago Torar (Iago Toral) rewrote the V3DV occlusion query code to improve the performance of the VideoCore Vulkan driver. "our implementation is mainly done by CPU, such as query reset and result replication, and some aspects of query availability tracking are handled by CPU," he explained in the merge request.

This new implementation handles all GPU query functions by scheduling computational shaders, which involves query availability, reset, and result replication. At present, this approach only supports managing occlusion queries, but performance queries (Performance queries) can also be implemented with some additional work in the future.

As an improvement on the open source raspberry pie Raspberry Pi graphics driver, more than 1000 lines of rewritten V3DV driver code have been incorporated into Mesa 23.0.

CTOnews.com learned that hardware occlusion queries are 3D API features that tell the application whether pixels will be drawn when rendering an object. When the bounding box is obscured, skip drawing the objects in the bounding box. Although this feature already exists, there are still two problems that affect its widespread use: the overhead of solving the occlusion query itself and the delay of waiting for query results.