// Apply the phong model to this point on the surface of the object, returning
// the color of that point.
Vec3d Material::shade(Scene *scene, const ray& r, const isect& i) const
{
const Material& m = i.getMaterial();
Vec3d I = m.ke(i) + prod(m.ka(i) ,scene->ambient());
Vec3d R = 2*(-r.getDirection() * i.N)*i.N +r.getDirection();
for ( vector<Light*>::const_iterator litr = scene->beginLights();
litr != scene->endLights();
++litr )
{
Vec3d atten = (*litr)->distanceAttenuation(r.at(i.t)) * (*litr)->shadowAttenuation(r,r.at(i.t));
I += prod(atten,(m.kd(i)*max((i.N * (*litr)->getDirection(r.at(i.t)) ), 0.0) + m.ks(i) * max(((scene->getCamera().getEye() - r.at(i.t)) *R),0.0)));
}
// You will need to call both the distanceAttenuation() and
// shadowAttenuation() methods for each light source in order to
// compute shadows and light falloff.
return I;
}
vec3f RayTracer::traceRay( Scene *scene, const ray& r,
const vec3f& thresh, int depth, isect& i, vector<const SceneObject*>& stack )
{
if( depth>=0
&& thresh[0] > threshold - RAY_EPSILON && thresh[1] > threshold - RAY_EPSILON && thresh[2] > threshold - RAY_EPSILON
&& scene->intersect( r, i ) ) {
// YOUR CODE HERE
// An intersection occured! We've got work to do. For now,
// this code gets the material for the surface that was intersected,
// and asks that material to provide a color for the ray.
// This is a great place to insert code for recursive ray tracing.
// Instead of just returning the result of shade(), add some
// more steps: add in the contributions from reflected and refracted
// rays.
const Material& m = i.getMaterial();
vec3f color = m.shade(scene, r, i);
//calculate the reflected ray
vec3f d = r.getDirection();
vec3f position = r.at(i.t);
vec3f direction = d - 2 * i.N * d.dot(i.N);
ray newray(position, direction);
if(!m.kr.iszero()) {
vec3f reflect = m.kr.multiply(traceRay(scene, newray, thresh.multiply(m.kr), depth-1, stack).clamp());
color += reflect;
}
//calculate the refracted ray
double ref_ratio;
double sin_ang = d.cross(i.N).length();
vec3f N = i.N;
//Decide going in or out
const SceneObject *mi = NULL, *mt = NULL;
int stack_idx = -1;
vector<const SceneObject*>::reverse_iterator itr;
//1 use the normal to decide whether to go in or out
//0: travel through, 1: in, 2: out
char travel = 0;
if(i.N.dot(d) <= -RAY_EPSILON) {
//from outer surface in
//test whether the object has two face
ray test_ray(r.at(i.t) + d * 2 * RAY_EPSILON, -d);
isect test_i;
if(i.obj->intersect(r, test_i) && test_i.N.dot(N) > -RAY_EPSILON) {
//has interior
travel = 1;
}
}
else {
travel = 2;
}
if(travel == 1) {
if(!stack.empty()) {
mi = stack.back();
}
mt = i.obj;
stack.push_back(mt);
}
else if(travel == 2) {
//if it is in our stack, then we must pop it
for(itr = stack.rbegin(); itr != stack.rend(); ++itr) {
if(*itr == i.obj) {
mi = *itr;
vector<const SceneObject*>::iterator ii = itr.base() - 1;
stack_idx = ii - stack.begin();
stack.erase(ii);
break;
}
}
if(!stack.empty()) {
mt = stack.back();
}
}
if(N.dot(d) >= RAY_EPSILON) {
N = -N;
}
ref_ratio = (mi?(mi->getMaterial().index):1.0) / (mt?(mt->getMaterial().index):1.0);
if(!m.kt.iszero() && (ref_ratio < 1.0 + RAY_EPSILON || sin_ang < 1.0 / ref_ratio + RAY_EPSILON)) {
//No total internal reflection
//We do refraction now
double c = N.dot(-d);
direction = (ref_ratio * c - sqrt(1 - ref_ratio * ref_ratio * (1 - c * c))) * N + ref_ratio * d;
newray = ray(position, direction);
vec3f refraction = m.kt.multiply(traceRay(scene, newray, thresh.multiply(m.kt), depth-1, stack).clamp());
color += refraction;
}
if(travel == 1) {
stack.pop_back();
}
else if(travel == 2) {
if(mi) {
stack.insert(stack.begin() + stack_idx, mi);
}
}
return color;
} else {
// No intersection. This ray travels to infinity, so we color
// it according to the background color, which in this (simple) case
// is just black.
if(m_bBackground && bg) {
double u, v;
angleToSphere(r.getDirection(), u, v);
//Scale to [0, 1];
u /= 2 * M_PI;
v /= M_PI;
int tx = int(u * bg_width), ty = bg_height - int(v * bg_height);
return vec3f(bg[3 * (ty * bg_width + tx)] / 255.0, bg[3 * (ty * bg_width + tx) + 1] / 255.0, bg[3 * (ty * bg_width + tx) + 2] / 255.0);
}
else {
return vec3f( 0.0, 0.0, 0.0 );
}
}
}