First Commit

For Azeroth!

dep/g3dlite/source/Triangle.cpp

@@ -0,0 +1,186 @@
+/**
+ @file Triangle.cpp
+ 
+ @maintainer Morgan McGuire, http://graphics.cs.williams.edu
+ 
+ @created 2001-04-06
+ @edited  2008-12-28
+
+ Copyright 2000-2009, Morgan McGuire.
+ All rights reserved.
+ */
+
+#include "G3D/platform.h"
+#include "G3D/Triangle.h"
+#include "G3D/Plane.h"
+#include "G3D/BinaryInput.h"
+#include "G3D/BinaryOutput.h"
+#include "G3D/debugAssert.h"
+#include "G3D/AABox.h"
+#include "G3D/Ray.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 = 0.5f * edgeDirection[0].cross(edgeDirection[2]).magnitude() * (edgeMagnitude[0] * edgeMagnitude[2]);
+        //0.5f * (_vertex[1] - _vertex[0]).cross(_vertex[2] - _vertex[0]).dot(_plane.normal());
+}
+
+
+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() {
+}
+
+
+Triangle::Triangle(class BinaryInput& b) {
+    deserialize(b);
+}
+
+
+void Triangle::serialize(class BinaryOutput& b) {
+    _vertex[0].serialize(b);
+    _vertex[1].serialize(b);
+    _vertex[2].serialize(b);
+}
+
+
+void Triangle::deserialize(class BinaryInput& b) {
+    _vertex[0].deserialize(b);
+    _vertex[1].deserialize(b);
+    _vertex[2].deserialize(b);
+    init(_vertex[0], _vertex[1], _vertex[2]);
+}
+
+
+float 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);
+}
+
+
+bool Triangle::intersect(const Ray& ray, float& distance, float baryCoord[3]) const {
+    static const float EPS = 1e-5f;
+
+    // See RTR2 ch. 13.7 for the algorithm.
+
+    const Vector3& e1 = edge01();
+    const Vector3& e2 = edge02();
+    const Vector3 p(ray.direction().cross(e2));
+    const float a = e1.dot(p);
+
+    if (abs(a) < EPS) {
+        // Determinant is ill-conditioned; abort early
+        return false;
+    }
+
+    const float f = 1.0f / a;
+    const Vector3 s(ray.origin() - vertex(0));
+    const float u = f * s.dot(p);
+
+    if ((u < 0.0f) || (u > 1.0f)) {
+        // We hit the plane of the m_geometry, but outside the m_geometry
+        return false;
+    }
+
+    const Vector3 q(s.cross(e1));
+    const float v = f * ray.direction().dot(q);
+
+    if ((v < 0.0f) || ((u + v) > 1.0f)) {
+        // We hit the plane of the triangle, but outside the triangle
+        return false;
+    }
+
+    const float t = f * e2.dot(q);
+
+    if ((t > 0.0f) && (t < distance)) {
+        // This is a new hit, closer than the previous one
+        distance = t;
+
+        baryCoord[0] = 1.0 - u - v;
+        baryCoord[1] = u;
+        baryCoord[2] = v;
+
+        return true;
+    } else {
+        // This hit is after the previous hit, so ignore it
+        return false;
+    }
+}
+
+} // G3D