vector volumeindexorigin(<geometry>geometry, int primnum)
vector volumeindexorigin(<geometry>geometry, string volumename)
The index of the bottom left of a volume primitive. For Volume primitives, this is always zero. However, for VDB primitives, this represents the bottom left of their active bounding box of voxels.
Returns 0 if
primnum is out of range, the geometry is invalid, or the given primitive is not a volume primitive.