bool IntersectTriangle(const MeshTriangle & tri, std::vector<G3D::Vector3>::const_iterator points, const G3D::Ray & ray, float & distance)
{
static const float EPS = 1e-5f;
// See RTR2 ch. 13.7 for the algorithm.
const G3D::Vector3 e1 = points[tri.idx1] - points[tri.idx0];
const G3D::Vector3 e2 = points[tri.idx2] - points[tri.idx0];
const G3D::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 G3D::Vector3 s(ray.origin() - points[tri.idx0]);
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 G3D::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;
}
// This hit is after the previous hit, so ignore it
return false;
}
