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 {
  12 }
  13
  14 Triangle::~Triangle()
  15 {
  16 }
  17
  18 bool
  19 Triangle::Intersect(Ray& ray)
  20 {
  21   const Vec3f edge1 = m_b-m_a;
  22   const Vec3f edge2 = m_c-m_a;
  23
  24   const Vec3f pvec = ray.direction().cross(edge2);
  25
  26   const float det = edge1.dot(pvec);
  27   if (fabs(det) < Epsilon) return false;
  28
  29   const float inv_det = 1.0f / det;
  30
  31   const Vec3f tvec = ray.origin()-m_a;
  32   float lambda = tvec.dot( pvec );
  33   lambda *= inv_det;
  34
  35   if (lambda < 0.0f || lambda > 1.0f)
  36     return false;
  37
  38   const Vec3f qvec = tvec.cross(edge1);
  39   float mue = ray.direction().dot(qvec);
  40   mue *= inv_det;
  41
  42   if (mue < 0.0f || mue+lambda > 1.0f)
  43     return false;
  44
  45   float f = edge2.dot(qvec);
  46   f *= inv_det;
  47   if (ray.t() <= f || f <  1e-4  )
  48     return false;
  49
  50   ray.setT(f);
  51
  52   return true;
  53 }
  54
  55 Vec3f
  56 Triangle::GetNormal(Ray& ray)
  57 {
  58   // normal is cross product of spanning vectors
  59   Vec3f n = (m_c - m_a) % (m_c - m_b);
  60   n.normalize();
  61   return n;
  62 }