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/**
@file Triangle.cpp
@maintainer Morgan McGuire, graphics3d.com
@created 2001-04-06
@edited 2006-01-20
Copyright 2000-2006, Morgan McGuire.
All rights reserved.
*/
#include "G3D/platform.h"
#include "G3D/Triangle.h"
#include "G3D/Plane.h"
#include "G3D/AABox.h"
namespace G3D {
void Triangle::init(const Vector3& v0, const Vector3& v1, const Vector3& v2) {
_plane = Plane(v0, v1, v2);
_vertex[0] = v0;
_vertex[1] = v1;
_vertex[2] = v2;
static int next[] = {1,2,0};
for (int i = 0; i < 3; ++i) {
const Vector3 e = _vertex[next[i]] - _vertex[i];
edgeMagnitude[i] = e.magnitude();
if (edgeMagnitude[i] == 0) {
edgeDirection[i] = Vector3::zero();
} else {
edgeDirection[i] = e / (float)edgeMagnitude[i];
}
}
edge01 = _vertex[1] - _vertex[0];
edge02 = _vertex[2] - _vertex[0];
_primaryAxis = _plane.normal().primaryAxis();
_area = (float)edgeDirection[0].cross(edgeDirection[2]).magnitude() * (edgeMagnitude[0] * edgeMagnitude[2]);
}
Triangle::Triangle() {
init(Vector3::zero(), Vector3::zero(), Vector3::zero());
}
Triangle::Triangle(const Vector3& v0, const Vector3& v1, const Vector3& v2) {
init(v0, v1, v2);
}
Triangle::~Triangle() {
}
double Triangle::area() const {
return _area;
}
const Vector3& Triangle::normal() const {
return _plane.normal();
}
const Plane& Triangle::plane() const {
return _plane;
}
Vector3 Triangle::center() const {
return (_vertex[0] + _vertex[1] + _vertex[2]) / 3.0;
}
Vector3 Triangle::randomPoint() const {
// Choose a random point in the parallelogram
float s = uniformRandom();
float t = uniformRandom();
if (t > 1.0f - s) {
// Outside the triangle; reflect about the
// diagonal of the parallelogram
t = 1.0f - t;
s = 1.0f - s;
}
return edge01 * s + edge02 * t + _vertex[0];
}
void Triangle::getBounds(AABox& out) const {
Vector3 lo = _vertex[0];
Vector3 hi = lo;
for (int i = 1; i < 3; ++i) {
lo = lo.min(_vertex[i]);
hi = hi.max(_vertex[i]);
}
out = AABox(lo, hi);
}
} // G3D
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