Vec4d Raytracer::shade(const RayIntersection& intersection,
size_t depth) const
{
// This offset must be added to intersection points for further
// traced rays to avoid noise in the image
const Vec3d offset(intersection.normal() * Math::safetyEps());
Vec4d color(0,0,0,1);
std::shared_ptr<const Renderable> renderable = intersection.renderable();
std::shared_ptr<const Material> material = renderable->material();
for(size_t i=0;i <mScene->lights().size();++i)
{
const Light &light = *(mScene->lights()[i].get());
//Shadow ray from light to hit point.
const Vec3d L = (intersection.position() + offset) - light.position();
const Ray shadowRay(light.position(), L);
//Shade only if light in visible from intersection point.
if (!mScene->anyIntersection(shadowRay,L.length()))
color += material->shade(intersection,light);
}
// limit recursion depth
if (depth >= mMaxDepth)
return color;
Vec3d dir = reflect(intersection.ray().direction(), intersection.normal());
Ray reflectedRay(intersection.position() + offset, dir);
double reflectance = material->reflectance();
color = color * (1 - reflectance) + reflectance * trace(reflectedRay, depth - 1) + Vec4d(0.0,0.0,0.0,1.0);
return color;
}
// use phong shading model
Vec4d PhongMaterial::shade(
const RayIntersection& intersection,
const Light& light) const
{
// calculate diffuse part of the equation
Vec3d lightDirection = (light.position() - intersection.position()).normalize();
Vec3d diffuse = this->color() * std::max(dot(intersection.normal(), lightDirection), 0.d);
// calculate specular part
Vec3d viewDirection = intersection.ray().direction();
Vec3d reflection = reflect(lightDirection, intersection.normal());
Vec3d lightcolor = light.spectralIntensity() / 255;
Vec3d specular = ((mShininess + 2) / (2 * M_PI)) * SPECULAR_REFLECTION_DEGREE * pow(std::max(dot(reflection, viewDirection), 0.d), mShininess) * lightcolor;
// calculcate sum -> result
return Vec4d(diffuse + specular, 1);
}