cae-tools/poly2d/p2d_area_holes.cpp

/*
 * p2d_area_holes.cpp - Fill an area with holes
 *
 * Written 2012 by Werner Almesberger
 * Copyright 2012 by Werner Almesberger
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

/*
 * References:
 * http://www.cgal.org/Manual/latest/examples/Straight_skeleton_2/
 *   Create_skeleton_and_offset_polygons_with_holes_2.cpp
 * http://www.cgal.org/Manual/latest/examples/Straight_skeleton_2/print.h
 */

extern "C" {
	#include <assert.h>

	#include "poly2d.h"
}

/*
 * @@@ Prevent spurious aborts with
 *
 * terminate called after throwing an instance of 'CGAL::Precondition_exception'
 * what():  CGAL ERROR: precondition violation!
 * Expr: is_simple_2(first, last, traits)
 * File: /usr/include/CGAL/Polygon_2/Polygon_2_algorithms_impl.h
 * Line: 420
 *
 * Note that we also need to check the polygons for simplicity in recurse_area,
 * or this may still lead to assertion failures.
 */

#define CGAL_POLYGON_NO_PRECONDITIONS

#include "cgal_helper.h"

#include <vector>
#include <boost/shared_ptr.hpp>

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Polygon_with_holes_2.h>
#include <CGAL/create_offset_polygons_from_polygon_with_holes_2.h>


typedef CGAL::Exact_predicates_inexact_constructions_kernel K;

typedef CGAL::Polygon_2<K> Polygon_2;
typedef CGAL::Polygon_with_holes_2<K> Polygon_with_holes;

typedef boost::shared_ptr<Polygon_with_holes> PolygonPtr;

typedef std::vector<PolygonPtr> PolygonPtrVector;

	struct p2d *res = NULL, **last = &res, *np;


static void append_poly(Polygon_2 poly, struct p2d ***last)
{
	**last = P2_to_p2d(poly);
	*last = &(**last)->next;
}


static void recurse_area(Polygon_with_holes poly, double current,
    double next, struct p2d ***last)
{
	if (!poly.outer_boundary().is_simple())
		return;
	for (Polygon_with_holes::Hole_const_iterator
	    hit = poly.holes_begin();
	    hit != poly.holes_end(); ++hit)
		if (!hit->is_simple())
			return;

	PolygonPtrVector tmp = 
	    CGAL::create_interior_skeleton_and_offset_polygons_with_holes_2(
	    current, poly);

	for (PolygonPtrVector::const_iterator pit = tmp.begin();
	    pit != tmp.end(); ++pit) {
		append_poly((*pit)->outer_boundary(), last);
		recurse_area(**pit, next, next, last);

		for (Polygon_with_holes::Hole_const_iterator
		    hit = (*pit)->holes_begin();
		    hit != (*pit)->holes_end(); ++hit) {
			append_poly(*hit, last);
		}
	}
}


extern "C" void p2d_area_holes_append(const struct p2d *p,
    const struct p2d *holes, double first, double next,
    struct p2d ***last)
{
	const struct p2d *h;

	assert(p2d_is_closed(p));
	Polygon_with_holes poly(p2d_to_P2(p, 1));

	for (h = holes; h; h = h->next) {
		assert(p2d_is_closed(h));
		poly.add_hole(p2d_to_P2(h, 0));
	}

	recurse_area(poly, first, next, last);
}


extern "C" struct p2d *p2d_area_holes(const struct p2d *p,
    const struct p2d *holes, double first, double next)
{
	struct p2d *res = NULL, **last = &res;

	p2d_area_holes_append(p, holes, first, next, &last);
	return res;
}