The 3DMark Mesh Shader feature test uses the mesh shader pipeline to implement a GPU-based culling solution.
The test shows how game engines can improve performance by using the mesh shader pipeline to efficiently cull geometry that is not visible to the camera.
The test scene is a hall containing many rows of highly detailed, carved pillars. As the camera moves through the scene, the pillars in the foreground block the view of those further back.
The test runs in two passes. The first pass uses the traditional geometry pipeline to provide a performance baseline. It uses compute shaders for LOD selection and meshlet culling. This reference implementation illustrates the performance overhead of the traditional approach.
The second pass uses the mesh shader pipeline. An amplification shader identifies meshlets that are visible to the camera and discards all others. The LOD system selects the correct LOD for groups of meshlets in the amplification shader. This allows for a more granular approach to LOD selection compared with selecting the LOD only at the object level. The visible meshlets are passed to the mesh shaders, which means the engine can ignore meshlets that are not visible to the camera.
The test measures the frame rate in frames per second for each pass. The result of the test is the average frame rate for each pass and the difference between them expressed as a percentage.