vcglib/wrap/io_trimesh/io_fan_tessellator.h

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/****************************************************************************
* VCGLib o o *
* Visual and Computer Graphics Library o o *
* _ O _ *
* Copyright(C) 2004-2016 \/)\/ *
* Visual Computing Lab /\/| *
* ISTI - Italian National Research Council | *
* \ *
* All rights reserved. *
* *
* 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. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License (http://www.gnu.org/licenses/gpl.txt) *
* for more details. *
* *
****************************************************************************/
#ifndef IO_FAN_TESSELLATOR_H
#define IO_FAN_TESSELLATOR_H
namespace vcg {
namespace tri {
namespace io {
/*
* A face polygon composed of more than three vertices is triangulated
* according to the following schema:
* v5
* / \
* / \
* / \
* v1------v4
* |\ /
* | \ /
* | \ /
* v2---v3
*
* As shown above, the 5 vertices polygon (v1,v2,v3,v4,v5)
* has been split into the triangles (v1,v2,v3), (v1,v3,v4) e (v1,v4,v5).
* This way vertex v1 becomes the common vertex of all newly generated
* triangles, and this may lead to the creation of very thin triangles.
*
* This function is intended as a trivial fallback when glutessellator is not available.
* it assumes just ONE outline
*/
template < class PointType>
void FanTessellator(const std::vector< std::vector<PointType> > & outlines, std::vector<int> & indices)
{
indices.clear();
if(outlines.empty()) return;
const std::vector<PointType> &points=outlines[0];
for(size_t i=0;i<points.size()-2;++i)
{
indices.push_back(0);
indices.push_back(i+1);
indices.push_back(i+2);
}
}
} // end Namespace tri
} // end Namespace io
} // end Namespace vcg
#endif // IO_FAN_TESSELLATOR_H