Sphere.cxx

   1 #include "Sphere.hxx"
   2
   3 Sphere::Sphere(const Vec3f& center, float radius, Shader* shader)
   4   : Primitive(shader),
   5     m_center(center),
   6     m_radius(radius)
   7 {
   8 }
   9
  10 Sphere::~Sphere()
  11 {
  12 }
  13
  14 bool
  15 Sphere::Intersect(Ray& ray)
  16 {
  17   float A = ray.direction().dot(ray.direction());
  18   float C = (ray.origin()-m_center).dot(ray.origin()-m_center) - m_radius*m_radius;
  19   float B = 2 * ray.direction().dot(ray.origin()-m_center);
  20
  21   if( B*B-4*A*C < 0 )
  22     return false;
  23
  24   float root = sqrtf(B*B-4*A*C);
  25   float t = (-B-root)/(2.0f*A);
  26   if(t > ray.t())
  27     return false;
  28
  29   if( t < 1e-6 )
  30     {
  31       t = (-B+root)/(2.0f*A);
  32       if( t < 1e-6 || t > ray.t())
  33         return false;
  34     }
  35   ray.setT(t);
  36   return true;
  37 }
  38
  39 Vec3f
  40 Sphere::GetNormal(Ray& ray)
  41 {
  42   // We don't want to modify the ray (probably this is not needed, but I am
  43   // too lazy to think about it now ...)
  44   Ray tempRay = ray;
  45
  46   // Surface normal is the difference between intersection and center point
  47   if(Intersect(tempRay)) {
  48     // intersection point
  49     Vec3f i = tempRay.origin() + tempRay.direction() * (tempRay.t() - Epsilon);
  50     // normal
  51     Vec3f n = (i - m_center);
  52     n.normalize();
  53     return n;
  54   } else {
  55     // no intersection with ray, so no surface normal
  56     return Vec3f(0,0,0);
  57   }
  58 }