/*
 * Triangle2D.cpp
 * 
 * Copyright (C) 2008 Matthias Schiffer <matthias@gamezock.de>
 * 
 * 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 3 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 for more details.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "Triangle2D.h"
#include <cmath>

namespace ZoomEdit {
namespace Math {

float Triangle2D::area() const {
  return std::fabs((vertices[0].y() + vertices[1].y())*(vertices[0].x()-vertices[1].x())
      + (vertices[1].y() + vertices[2].y())*(vertices[1].x()-vertices[2].x())
      + (vertices[2].y() + vertices[0].y())*(vertices[2].x()-vertices[0].x()))/2;
}

bool Triangle2D::contains(const vmml::vec2f &v) const {
  for(int i = 0; i < 3; ++i) {
    vmml::vec2f v1 = vertices[(i+2)%3] - vertices[(i+1)%3];
    vmml::vec2f v2 = vertices[i] - vertices[(i+1)%3];
    
    vmml::vec2f vp = v - vertices[(i+1)%3];
    
    if((v1.x()*vp.y()-vp.x()*v1.y())*(v1.x()*v2.y()-v2.x()*v1.y()) < 0)
      return false;
  }
  
  return true;
}

}
}