bool KRTriangle3::containsPoint(const KRVector3 &p) const
{
/*
// From: http://stackoverflow.com/questions/995445/determine-if-a-3d-point-is-within-a-triangle
const float SMALL_NUM = 0.00000001f; // anything that avoids division overflow
// KRVector3 A = m_c[0], B = m_c[1], C = m_c[2];
if (_sameSide(p, m_c[0], m_c[1], m_c[2]) && _sameSide(p, m_c[1], m_c[0], m_c[2]) && _sameSide(p, m_c[2], m_c[0], m_c[1])) {
KRVector3 vc1 = KRVector3::Cross(m_c[0] - m_c[1], m_c[0] - m_c[2]);
if(fabs(KRVector3::Dot(m_c[0] - p, vc1)) <= SMALL_NUM) {
return true;
}
}
return false;
*/
// From: http://blogs.msdn.com/b/rezanour/archive/2011/08/07/barycentric-coordinates-and-point-in-triangle-tests.aspx
KRVector3 A = m_c[0];
KRVector3 B = m_c[1];
KRVector3 C = m_c[2];
KRVector3 P = p;
// Prepare our barycentric variables
KRVector3 u = B - A;
KRVector3 v = C - A;
KRVector3 w = P - A;
KRVector3 vCrossW = KRVector3::Cross(v, w);
KRVector3 vCrossU = KRVector3::Cross(v, u);
// Test sign of r
if (KRVector3::Dot(vCrossW, vCrossU) < 0)
return false;
KRVector3 uCrossW = KRVector3::Cross(u, w);
KRVector3 uCrossV = KRVector3::Cross(u, v);
// Test sign of t
if (KRVector3::Dot(uCrossW, uCrossV) < 0)
return false;
// At this point, we know that r and t and both > 0.
// Therefore, as long as their sum is <= 1, each must be less <= 1
float denom = uCrossV.magnitude();
float r = vCrossW.magnitude() / denom;
float t = uCrossW.magnitude() / denom;
return (r + t <= 1);
}
bool _intersectSphere(const KRVector3 &start, const KRVector3 &dir, const KRVector3 &sphere_center, float sphere_radius, float &distance)
{
// dir must be normalized
// From: http://archive.gamedev.net/archive/reference/articles/article1026.html
// TODO - Move to another class?
KRVector3 Q = sphere_center - start;
float c = Q.magnitude();
float v = KRVector3::Dot(Q, dir);
float d = sphere_radius * sphere_radius - (c * c - v * v);
if(d < 0.0) {
// No intersection
return false;
}
// Return the distance to the [first] intersecting point
distance = v - sqrt(d);
if(distance < 0.0f) {
return false;
}
return true;
}
