public static Color TraceRay(Vector3 start, Vector3 dir, Scene scene, int depth_)
{
if (depth_ >= scene.MaxRayDepth)
{
return(scene.Ambient);
}
Ray ray = new Ray()
{
Start = start, Dir = dir
};
Intersection isect = scene.FirstIntersect(ray);
if (null == isect)
{
return(scene.Background);
}
//light hit
Surface surf = isect.Thing.Surface;
Vector3 pos = isect.Ray.Start + isect.Dist * isect.Ray.Dir;
Vector3 invRayDir = -isect.Ray.Dir;
Vector3 normal = isect.Thing.Normal(pos, isect.Inside);
Vector3 reflect = Vector3.Reflect(normal, invRayDir);
Color ambient = scene.Ambient;
Color local = LocalLighting(surf, pos, normal, reflect, scene);
float refl = surf.Reflect(pos);
float alpha = surf.Alpha(pos);
Color reflected = Color.Black();
if (0 < refl && 0 < alpha)
{
reflected = TraceRay(pos + .001 * reflect, reflect, scene, depth_ + 1) * refl;
}
Color transmitted = Color.Black();
if (1 > alpha)
{
double eta = isect.Inside ? 1 / surf.Eta : surf.Eta;
Vector3 transmit = Vector3.Refract(normal, invRayDir, eta);
transmitted = TraceRay(pos + .001 * transmit, transmit, scene, depth_ + 1);
}
return(ambient + (local + reflected) * alpha + transmitted * (1 - alpha));
}