volumeindex expression function

Returns the value of a volume primitive at a specified voxel.

See also: volumesample

The coordinates are in terms of the voxel grid, not world coordinates. 0, 0, 0 means the first voxel.

surface_node is the full path of the surface node. prim_id is the primitive number of the volume primitive within the surface node.

Returns 0 if out of bound values are specified, or the given primitive is not a volume.

volumeindex("/obj/geo1/isooffset1", 0, 3, 4, 5)