proxy_voxelize

One thread per scene triangle. Marks every voxel the triangle's world-space bounding box covers as occupied, in the sp_occupancy volume.

Scattering from triangles keeps the cost proportional to the scene's surface area rather than to the volume of the grid. Marking the bounding box rather than the exact triangle overstates occupancy by at most a voxel in each direction — the direction a proxy should err, since a query is then answered "something is here" slightly too often rather than missing a surface.

Threads racing on a shared voxel all store the same value, so no ordering is required.