Given a tet mesh on the first input and a polygon mesh enclosing various areas on the second input, assign a piece attribute to each tet specifying which partition it belongs to. Regions of tets that are not fully enclosed by polygons of the second input get the special piece value -1 (meaning invalid).
If the second input has the piece attribute, then the output piece attribute is based on the piece attributes of the backward facing polygons that surround the region to which a tet belongs. If a region of tets is surrounded by polygons that have multiple piece attributes, then a piece value that occurs most often is used.
If the second input has no piece attribute, then the regions are assigned successive numbers.
Group of tets to consider from the first input.
Group of polygons to consider from the second input.
The name of the piece attribute to generate.