int setprimgroup(int geohandle, string name, int prim_num, int value, string mode="set")
A handle to the geometry to write to. Currently the only valid value is
0 or geoself, which means the current geometry in a node. (This argument may be used in the future to allow writing to other geometries.)
The name of the group to modify.
The primitive number to add or remove from the group.
1 to put the primitive in the group,
0 to remove the primitive from the group.
This is ignored if
"set" to set the primitive’s membership according to the
"toggle" to toggle the primitive’s membership, regardless of the