Ray / Triangle交点？

Question

我想将此算法用于光线/三角交叉测试：

#define EPSILON 0.000001

int triangle_intersection( const Vec3   V1,  // Triangle vertices
                           const Vec3   V2,
                           const Vec3   V3,
                           const Vec3    O,  //Ray origin
                           const Vec3    D,  //Ray direction
                                 float* out )
{
  Vec3 e1, e2;  //Edge1, Edge2
  Vec3 P, Q, T;
  float det, inv_det, u, v;
  float t;

  //Find vectors for two edges sharing V1
  SUB(e1, V2, V1);
  SUB(e2, V3, V1);
  //Begin calculating determinant - also used to calculate u parameter
  CROSS(P, D, e2);
  //if determinant is near zero, ray lies in plane of triangle
  det = DOT(e1, P);
  //NOT CULLING
  if(det > -EPSILON && det < EPSILON) return 0;
  inv_det = 1.f / det;

  //calculate distance from V1 to ray origin
  SUB(T, O, V1);

  //Calculate u parameter and test bound
  u = DOT(T, P) * inv_det;
  //The intersection lies outside of the triangle
  if(u < 0.f || u > 1.f) return 0;

  //Prepare to test v parameter
  CROSS(Q, T, e1);

  //Calculate V parameter and test bound
  v = DOT(D, Q) * inv_det;
  //The intersection lies outside of the triangle
  if(v < 0.f || u + v  > 1.f) return 0;

  t = DOT(e2, Q) * inv_det;

  if(t > EPSILON) { //ray intersection
    *out = t;
    return 1;
  }

  // No hit, no win
  return 0;
}

然而，我在理解它时遇到了一些麻烦。此算法是否仅测试交叉点是否存在？我希望能够检索光线与三角形相交的点。

感谢您的帮助。