algorithm.inl

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/** @file
 *  @author Bram de Greve (bramz@users.sourceforge.net)
 *  @author Tom De Muer (tomdemuer@users.sourceforge.net)
 *
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 *  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.
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 *  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.
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 */

namespace lass
{
namespace prim
{


template<typename T, class DegeneratePolicy>
bool triangulate(const SimplePolygon2D<T, DegenerationPolicy>& iPolygon,
                 std::vector<Triangle2D<T> >& oTriangles)
{
    oTriangles.clear();
    if (iPolygon.isConvex())
    {
        // this is the easy one :)
        int i=0;
        for (;i<iPolygon.size()-3;++i)
            oTriangles.push_back(Triangle2D<T>(iPolygon[0],iPolygon[i+1],iPolygon[i+2] ) );
        return true;
    }

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

    SimplePolygon2D<T, DegenerationPolicy> temp(iPolygon);
    while (temp.size()>3)
    {
        int i=0;
        for (;i<temp.size();++i)
        {
            if (temp.isReflex(i))
            {
                oTriangles.push_back(Triangle2D<T>(temp[i-1],temp[i],temp[i+1]));
                temp.erase(i);
                break;
            }
        }
    }
    oTriangles.push_back(Triangle2D<T>(temp[0],temp[1],temp[2]));
    return true;
}

}
}