Triangle.cxx

   1 #include "Triangle.hxx"
   2
   3 Triangle::Triangle(const Vec3f& a,
   4                    const Vec3f& b,
   5                    const Vec3f& c,
   6                    Shader* shader)
   7   : Primitive(shader),
   8     m_a(a),
   9     m_b(b),
  10     m_c(c),
  11     m_n( (b-a).cross(c-a) )
  12 {
  13   m_n.normalize();
  14 }
  15
  16 Triangle::~Triangle()
  17 {
  18 }
  19
  20 bool
  21 Triangle::Intersect(Ray& ray)
  22 {
  23   const Vec3f edge1 = m_b-m_a;
  24   const Vec3f edge2 = m_c-m_a;
  25
  26   const Vec3f pvec = ray.direction().cross(edge2);
  27
  28   const float det = edge1.dot(pvec);
  29   if (fabs(det) < Epsilon) return false;
  30
  31   const float inv_det = 1.0f / det;
  32
  33   const Vec3f tvec = ray.origin()-m_a;
  34   float lambda = tvec.dot( pvec );
  35   lambda *= inv_det;
  36
  37   if (lambda < 0.0f || lambda > 1.0f)
  38     return false;
  39
  40   const Vec3f qvec = tvec.cross(edge1);
  41   float mue = ray.direction().dot(qvec);
  42   mue *= inv_det;
  43
  44   if (mue < 0.0f || mue+lambda > 1.0f)
  45     return false;
  46
  47   float f = edge2.dot(qvec);
  48   f *= inv_det;
  49   if (ray.t() <= f || f < Epsilon )
  50     return false;
  51
  52   ray.setT(f);
  53   ray.setHit(this);
  54
  55   return true;
  56 }
  57
  58 Vec3f
  59 Triangle::GetNormal(Ray& ray)
  60 {
  61   return m_n;
  62 }