The geometry's index (reordered by three-mesh-bvh without indirect), or null.
Tree position to triangle (indirect mode), or null.
One buffer of 32-byte nodes per root (one per group without indirect).
Optionalversion1 for three-mesh-bvh 0.7 and later; missing (0) for older files.
three-mesh-bvh's
SerializedBVH: whatMeshBVH.serializereturns andMeshBVH.deserializetakes.