bool UVSphere::hit(const Ray3D& r, float tmin, float tmax, float time, HitRecord& record) const
{
Vector3D temp = r.getOrigin() - center;
double a = dotProduct(r.getDirection(), r.getDirection());
double b = 2*dotProduct(r.getDirection(), temp);
double c = dotProduct(temp, temp) - radius*radius;
double disc = b*b -4*a*c;
//is there some intersection
if(disc > 0.0) {
disc = sqrt(disc);
double t = (-b - disc) / (2.0*a);
if (t < tmin)
t = (-b + disc) /(2.0*a);
if (t < tmin || t > tmax)
return false;
record.t = t;
record.p = record.texp = (r.getOrigin() + t*r.getDirection());
record.uvw.initFromW((record.p - center) / radius);
Vector3D n = (record.p - center) / radius;
float twopi = 6.28318530718f;
float theta = acos(n.getZ());
float phi = atan2(n.getY(), n.getX());
if (phi < 0.0f) phi+= twopi;
float one_over_2pi = .159154943029f;
float one_over_pi = .318309886184f;
float pi = 3.14159;
record.uv = Vector2D(phi*one_over_2pi, (pi-theta)*one_over_pi);
record.mat_ptr = material;
return true;
}
return false;
}
/**
* A ray is represented by l0 + l * t = p
* l0 - ray origin
* l - ray direction
* t - parameter
* p - point on plane
* A plane is represented by (p - p0) dot n = 0 (because perpendicular)
* p0 - a point representing the distance from the origin
* n - normal of plane
* Solving for t by substituting p gives that
* t = [ (p0 - l0) dot n ] / [ l dot n ]
*/
double Plane::findIntersection(const Ray3D & ray) const {
Vector3D rayDirection = ray.getDirection();
Vector3D l = rayDirection;
Vector3D n = normal;
double ldotn = l.dotProduct(n);
if (0 == ldotn) { // Ray is || to plane
return -1; // Never intersects
} else {
Vector3D p0 = normal * distance;
Vector3D l0 = ray.getOrigin();
double numerator = (p0 - l0).dotProduct(n);
return numerator / ldotn;
}
}
bool UVSphere::shadowHit(const Ray3D& r, float tmin, float tmax, float time) const
{
Vector3D temp = r.getOrigin() - center;
double a = dotProduct(r.getDirection(), r.getDirection());
double b = 2*dotProduct(r.getDirection(), temp);
double c = dotProduct(temp, temp) - radius*radius;
double disc = b*b -4*a*c;
//is there some intersection
if(disc > 0.0) {
disc = sqrt(disc);
double t = (-b - disc) / (2.0*a);
if (t < tmin)
t = (-b + disc) /(2.0*a);
if (t < tmin || t > tmax)
return false;
return true;
}
return false;
}
Color RayTracer::traceRay (Ray3D ray, float distance) {
Primitive* closestPrim = NULL;
float newDistance;
Color color (0.0, 0.0, 0.0);
for (int i = 0; i < _scene->getNumberOfPrimitives (); i++) {
newDistance = _scene->getPrimitive (i)->findIntersectionWith (ray, distance);
if ((newDistance >= 0.0) && (newDistance < distance)) {
closestPrim = _scene->getPrimitive (i);
distance = newDistance;
}
}
if (closestPrim == NULL) {
return color;
}
if (closestPrim->getIsLight ()) {
color = closestPrim->getColor ();
return color;
}
// calculate diffuse lighting
Vector3 pointOfIntersection = ray.getDirection () * distance + ray.getOrigin ();
Vector3 normal = closestPrim->getNormalAt (pointOfIntersection);
for (int i = 0; i < _scene->getNumberOfPrimitives (); i++) {
Primitive* light = _scene->getPrimitive (i);
if (!light->getIsLight ()) {
// wait, this isn't actually a light ...
continue;
}
Vector3 lightDir = light->getOrigin () - pointOfIntersection;
lightDir.normalize();
float lightCoef = normal.dotProduct (lightDir);
color = color + closestPrim->getColor () * light->getColor () * lightCoef;
}
return color;
}
// Return distance from ray origin to intersection
// See comments for variables and the equations in Plane.cpp's findIntersection
double Triangle::findIntersection(const Ray3D & ray) const {
// See if the ray intersects the bounding box
// *** With bounding box
if (!Object::intersectsBBox(ray)) { return -1; }
// First check if the ray intersects with the plane (use same calculations)
Vector3D rayDirection = ray.getDirection();
Vector3D rayOrigin = ray.getOrigin();
double ldotn = rayDirection.dotProduct(normal);
if (0 == ldotn) { // Ray is || to triangle
return -1;
} else {
Vector3D p0 = normal * distance;
double distanceToPlane = (p0 - rayOrigin).dotProduct(normal) / ldotn;
// Then see if the point is inside the triangle (3 conditions)
// Q is the point of intersection
Vector3D Q = (rayDirection * distanceToPlane) + rayOrigin;
Vector3D sideCA = epC - epA;
Vector3D segQA = Q - epA;
// 1. (CA x QA) * n >= 0
if (sideCA.crossProduct(segQA).dotProduct(normal) < 0) {
return -1;
}
Vector3D sideBC = epB - epC;
Vector3D segQC = Q - epC;
// 2. (BC x QC) * n >= 0
if (sideBC.crossProduct(segQC).dotProduct(normal) < 0) {
return -1;
}
Vector3D sideAB = epA - epB;
Vector3D segQB = Q - epB;
// 3. (AB x QB) * n >= 0
if (sideAB.crossProduct(segQB).dotProduct(normal) < 0) {
return -1;
}
return distanceToPlane;
}
}
