Scaffolding for Phase 3E (GPU compute cull). After finalizeModel /
applyCachedModel, pack each InstanceCpu's world AABB + mesh_id +
reflection bit into a std430-friendly 32 B record and push it to a
per-model aabb_ssbo. No consumer yet — the CPU cull still drives
rendering — but the next commits will point a compute shader at this
buffer and have it produce the visible list + indirect commands
directly on the GPU.
Cost: 32 B per instance, ~18 MB for the 569 k-instance test scene.
One-shot upload at finalize time; streaming-time appends aren't
mirrored (the CPU cull doesn't need the SSBO, and finalizeModel
rebuilds the whole thing in one go).
Dion Moult
2f88778c9f