CGAL 6.1 - 2D Boolean Operations on Nef Polygons

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Nef_2/nef_2_exploration.cpp
#include <CGAL/Exact_integer.h>
#include <CGAL/Filtered_extended_homogeneous.h>
#include <CGAL/Nef_polyhedron_2.h>
typedef CGAL::Exact_integer RT;
typedef CGAL::Filtered_extended_homogeneous<RT> Extended_kernel;
typedef CGAL::Nef_polyhedron_2<Extended_kernel> Nef_polyhedron;
typedef Nef_polyhedron::Point Point; // a standard point
typedef Nef_polyhedron::Line Line;
typedef Nef_polyhedron::Explorer Explorer;
typedef Explorer::Face_const_iterator Face_const_iterator;
typedef Explorer::Hole_const_iterator Hole_const_iterator;
typedef Explorer::Halfedge_around_face_const_circulator Halfedge_around_face_const_circulator;
typedef Explorer::Vertex_const_handle Vertex_const_handle;
void explore(std::string s, const Nef_polyhedron& poly)
{
std::cout << "Explore: " << s << std::endl;
Explorer explorer = poly.explorer();
int i = 0;
for(Face_const_iterator fit = explorer.faces_begin(); fit != explorer.faces_end(); ++fit, i++){
std::cout << "\nFace " << i << std::endl
<< ( explorer.mark(fit)? "* is" : "* is not") << " marked" << std::endl;
// explore the outer face cycle if it exists
Halfedge_around_face_const_circulator hafc = explorer.face_cycle(fit);
if(hafc == Halfedge_around_face_const_circulator()){
std::cout << "* has no outer face cycle" << std::endl;
} else {
std::cout << "* outer face cycle:\n";
std::cout << " - halfedges around the face: ";
Halfedge_around_face_const_circulator done(hafc);
do {
char c = (explorer.is_frame_edge(hafc))?'f':'e';
std::cout << c;
++hafc;
}while (hafc != done);
std::cout << " ( f = frame edge, e = ordinary edge)" << std::endl;
std::cout << " - vertices around the face:\n";
do {
Vertex_const_handle vh = explorer.target(hafc);
if (explorer.is_standard(vh)){
std::cout << " " << explorer.point(vh) << std::endl;
}else{
std::cout << " " << explorer.ray(vh) << std::endl;
}
++hafc;
}while (hafc != done);
}
// explore the holes if the face has holes
Hole_const_iterator hit = explorer.holes_begin(fit), end = explorer.holes_end(fit);
if(hit == end){
std::cout << "* has no hole" << std::endl;
}else{
std::cout << "* has holes" << std::endl;
for(; hit != end; hit++){
Halfedge_around_face_const_circulator hafc(hit), done(hit);
std::cout << " - halfedges around the hole: ";
do {
char c = (explorer.is_frame_edge(hafc))?'f':'e';
std::cout << c;
++hafc;
}while (hafc != done);
std::cout << " ( f = frame edge, e = ordinary edge)" << std::endl;
}
}
}
std::cout << "done\n" << std::endl;
}
int main() {
CGAL::IO::set_pretty_mode(std::cout);
Nef_polyhedron N0(Nef_polyhedron::COMPLETE);
explore("complete", N0);
Line l(0,1,-2); // l : 0x + y - 2 = 0
Nef_polyhedron N1(l,Nef_polyhedron::INCLUDED);
explore("line", N1);
Point p1(1,1), p2(10,1), p3(10,10);
Point triangle[3] = { p1, p2, p3 };
Nef_polyhedron N2(triangle, triangle+3);
explore("triangle", N2);
{
Point p1(4,2), p2(6,2), p3(6,4);
Point triangle[3] = { p1, p2, p3 };
Nef_polyhedron N3(triangle, triangle+3);
N2 -= N3;
}
{
Point p1(7,2), p2(9,2), p3(9,6);
Point triangle[3] = { p1, p2, p3 };
Nef_polyhedron N3(triangle, triangle+3);
N2 -= N3;
}
explore("triangle with two triangular holes", N2);
return 0;
}
Exact_integer.h
CGAL::Filtered_extended_homogeneous
The class Filtered_extended_homogeneous serves as a traits class for the class Nef_polyhedron_2<T>.
Definition: Filtered_extended_homogeneous.h:20
CGAL::Nef_polyhedron_2::Topological_explorer::face_cycle
Halfedge_around_face_const_circulator face_cycle(Face_const_handle f)
returns a circulator for the outer face cycle of f.
CGAL::Nef_polyhedron_2
An instance of data type Nef_polyhedron_2<T> is a subset of the plane that is the result of forming c...
Definition: Nef_polyhedron_2.h:92
CGAL::Nef_polyhedron_2::explorer
Explorer explorer()
returns a decorator object that allows read-only access of the underlying plane map.
unspecified_type
CGAL::IO::set_pretty_mode
Mode set_pretty_mode(std::ios &s)