simple_polygon_2d_triangle_2d.h

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/** @file
 *  @author Bram de Greve (bramz@users.sourceforge.net)
 *  @author Tom De Muer (tomdemuer@users.sourceforge.net)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2007 the Initial Developer.
 *  All Rights Reserved.
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 *  GNU General Public License Version 2 or later (the GPL), in which case the 
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 *  deleting the provisions above and replace them with the notice and other 
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 */

#ifndef LASS_GUARDIAN_OF_INCLUSION_PRIM_SIMPLE_POLYGON_2D_TRIANGLE_2D_H
#define LASS_GUARDIAN_OF_INCLUSION_PRIM_SIMPLE_POLYGON_2D_TRIANGLE_2D_H

#include "prim_common.h"
#include "simple_polygon_2d.h"
#include "triangle_2d.h"

namespace lass
{
namespace prim
{

template <typename T, class DegeneratePolicy, typename OutputIterator>
OutputIterator triangulate(
        const SimplePolygon2D<T, DegenerationPolicy>& polygon, OutputIterator triangles)
{
    if (polygon.isConvex())
    {
        // this is the easy one :)
        const size_t n = polygon.size() - 3;
        for (size_t i = 0; i < n; ++i)
        {
            *triangles++ = Triangle2D<T>(polygon[0],polygon[i+1],polygon[i+2]);
        }
        return triangles;
    }

    // we implement the easiest algorithm: ear clipping
    // we try to find a non-reflex vertex and then clip it

#pragma LASS_FIXME("This naive implementation of ear clipping is broken, let's fix it later =) [Bramz]")
    LASS_THROW("triangulation of concave polygons is not implemented yet [Bramz]");
    //SimplePolygon2D<T, DegenerationPolicy> temp(polygon);
    //while (temp.size()>3)
    //{
    //  const int n = temp.size();
    //  for (int i=0;i<n;++i)
    //  {
    //      if (temp.isReflex(i))
    //      {
    //          *triangles++ = push_back(Triangle2D<T>(temp.at(i-1),temp[i],temp.at(i+1)));
    //          temp.erase(i);
    //          break;
    //      }
    //  }
    //}
    //*triangles++ = Triangle2D<T>(temp[0],temp[1],temp[2]);
    //return triangles;
}

}
}

#endif