QuadAreaLight.cxx

   1 #include <cmath>
   2 #include <cstdlib>
   3
   4 #include "QuadAreaLight.hxx"
   5
   6 QuadAreaLight::QuadAreaLight(Scene* scene,
   7                              const Vec3f& intensity,
   8                              const Vec3f& p1,
   9                              const Vec3f& p2,
  10                              const Vec3f& p3,
  11                              const Vec3f& p4)
  12   : Light(scene),
  13     m_p0(p1),
  14     m_e1(p2-p1),
  15     m_e2(p3-p1),
  16     m_intensity(intensity)
  17 {
  18   m_n = m_e1.cross(m_e2);
  19   m_area = m_n.norm();
  20   m_n.normalize();
  21 }
  22
  23 QuadAreaLight::QuadAreaLight()
  24   : Light(0),
  25     m_p0(Vec3f()),
  26     m_e1(Vec3f()),
  27     m_e2(Vec3f()),
  28     m_n(Vec3f()),
  29     m_intensity(Vec3f())
  30 {
  31 }
  32
  33 QuadAreaLight::~QuadAreaLight()
  34 {
  35 }
  36
  37 bool
  38 QuadAreaLight::Illuminate(Ray& shadow_ray, Vec3f& intensity)
  39 {
  40   // generate random factors
  41   float xi1 = drand48();
  42   float xi2 = drand48();
  43
  44   // bilinear interpolation of position
  45   Vec3f pos = m_p0 + m_e1 * xi1 + m_e2* xi2;
  46   // direction of shadow ray
  47   Vec3f dir = pos-shadow_ray.origin();
  48
  49   float dist = dir.norm();
  50   float cosN = (dir.dot(m_n)) / dist;
  51
  52   if(cosN <= 0.0f )
  53     return false;
  54
  55   // squared falloff and projected area
  56   intensity = m_intensity * ( m_area * cosN / ( dist*dist));
  57
  58   dir.normalize();
  59   shadow_ray.setDir(dir);
  60   shadow_ray.setT(dist);
  61
  62   return true;
  63 }
  64
  65 bool
  66 QuadAreaLight::IsArea()
  67 {
  68   return true;
  69 }
  70
  71 const Vec3f&
  72 QuadAreaLight::GetNormal(const Vec3f& pos) const
  73 {
  74   return m_n;
  75 }