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//
// libavg - Media Playback Engine.
// Copyright (C) 2003-2014 Ulrich von Zadow
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
// Current versions can be found at www.libavg.de
//
#include "Triangle.h"
#include "GLMHelper.h"
#include <math.h>
namespace avg {
Triangle::Triangle(const glm::vec2& P0, const glm::vec2& P1, const glm::vec2& P2)
: p0(P0),
p1(P1),
p2(P2)
{
}
Triangle::Triangle()
{
}
bool Triangle::operator ==(const Triangle & tri) const
{
return (p0 == tri.p0 && p1 == tri.p1 && p2 == tri.p2);
}
bool Triangle::isInside(const glm::vec2& pt) const
{
/* Slower func that only works for cw triangles.
glm::vec2 a = p2-p1;
glm::vec2 bp = pt-p1;
float aCROSSbp = a.x*bp.y - a.y*bp.x;
if (aCROSSbp < 0.0) {
return false;
}
glm::vec2 b = p0-p2;
glm::vec2 cp = pt-p2;
float bCROSScp = b.x*cp.y - b.y*cp.x;
if (bCROSScp < 0.0) {
return false;
}
glm::vec2 c = p1-p0;
glm::vec2 ap = pt-p0;
float cCROSSap = c.x*ap.y - c.y*ap.x;
return cCROSSap >= 0.0;
*/
glm::vec2 v0 = p2 - p0;
glm::vec2 v1 = p1 - p0;
glm::vec2 v2 = pt - p0;
float dot00 = glm::dot(v0, v0);
float dot01 = glm::dot(v0, v1);
float dot02 = glm::dot(v0, v2);
float dot11 = glm::dot(v1, v1);
float dot12 = glm::dot(v1, v2);
float invDenom = 1 / (dot00 * dot11 - dot01 * dot01);
float u = (dot11 * dot02 - dot01 * dot12) * invDenom;
float v = (dot00 * dot12 - dot01 * dot02) * invDenom;
return (u > 0) && (v > 0) && (u + v < 1);
}
float Triangle::getArea() const
{
return fabs((((p1.x-p0.x)*(p2.y-p0.y)) - ((p1.y-p0.y)*(p2.x-p0.x)))/2);
}
bool Triangle::isClockwise() const
{
return ((p1.x-p0.x)*(p2.y-p0.y)) - ((p1.y-p0.y)*(p2.x-p0.x)) < 0;
}
std::ostream& operator<<(std::ostream& os, const Triangle& tri)
{
os << "(" << tri.p0 << "," << tri.p1 << "," << tri.p2 << ")";
return os;
}
}
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