CGAL users discussion list

[Stephen Wong <>]

Hello,

 

Nef Polyhedra has a well-defined set of volume and shell iterators.  However, after converting Nef Polyhedra back to B-rep Polyhedra using Nef_polyhedron_3<>::convert_to_Polyhedron() (after a Boolean operation, for example), the Polyhedron class does not have similar iterators.

 

How can I iterate the faces between different “volumes” or “shells” in a Polyhedron?

 

A concrete example:

Nef polyhedron N1 is a box with lower left (0,0,0) and upper right (3,3,3)

Nef polyhedron N2 is a box with lower left (1,1,1) and upper right (2,2,2)

N1 -= N2 ; // difference boolean operator

N1.convert_to_Polyhedron() ;

 

This resultant Polyhedron has an outer shell and an inner shell bounding the void inside the cube.  I want to access facets for each shell of the Polyhedron.  The function facets_begin() provided in the Polyhedron class iterates through all facets in the polyhedron, i.e. all shells without distinction.

 

Thanks,

 

Stephen Wong