QuadAreaLight.cxx

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