@Override
public Illumination illuminate(Vec3D point) {
Vec3D lightDirection = point.subtract(position);
double r2 = lightDirection.dotProduct(lightDirection);
double distance = Math.sqrt(r2);
lightDirection = lightDirection.multiply(1 / distance);
Vec3D lightIntensity = color.multiply(intensity / (4 * Math.PI * r2));
return new Illumination(lightDirection, lightIntensity, distance);
}
@Override
public Double intersect(Ray ray) {
Vec3D o = worldToObject.multiplyPoint(ray.origin);
o.setY(o.getY() + ymax + (ymin - ymax) * 0.5);
Vec3D d = worldToObject.multiplyDirection(ray.direction);
double sin2 = radius2 / (radius2 + height * height);
double cos2 = 1 - sin2;
double a = d.getX() * d.getX() * cos2 + d.getZ() * d.getZ() * cos2 - d.getY() * d.getY() * sin2;
double b =
2 * (o.getX() * d.getX() * cos2 + o.getZ() * d.getZ() * cos2 - o.getY() * d.getY() * sin2);
double c = o.getX() * o.getX() * cos2 + o.getZ() * o.getZ() * cos2 - o.getY() * o.getY() * sin2;
QuadraticRoots roots = Utils.solveQuadratic(a, b, c);
boolean isect = false;
double t0 = 0, t1 = 0, t = Double.POSITIVE_INFINITY;
Vec3D n = new Vec3D();
if (roots != null) {
if (roots.x0 > roots.x1) {
t0 = roots.x1;
t1 = roots.x0;
} else {
t0 = roots.x0;
t1 = roots.x1;
}
if (t0 < 0) {
t0 = t1;
}
double y = o.getY() + t0 * d.getY();
if (y > ymax || y < ymin) {
t0 = t1;
y = o.getY() + t0 * d.getY();
}
if (y >= ymin && y <= ymax && t0 >= 0) {
isect = true;
t = t0;
Vec3D p = o.add(d.multiply(t0));
Vec3D tangent = new Vec3D(0, 1, 0).crossProduct(new Vec3D(p.getX(), 0, p.getZ()));
Vec3D bitangent = p.multiply(-1);
n = objectToWorld.multiplyDirection(tangent.crossProduct(bitangent)).normalize();
}
t0 = (ymin - o.getY()) / d.getY();
double xx = o.getX() + t0 * d.getX();
double zz = o.getZ() + t0 * d.getZ();
if (xx * xx + zz * zz <= radius2 && t0 < t && t0 >= 0) {
isect = true;
t = t0;
n = objectToWorld.multiplyDirection(new Vec3D(0, -1, 0));
}
if (radius0 != 0) {
t0 = (ymax - o.getY()) / d.getY();
xx = o.getX() + t0 * d.getX();
zz = o.getZ() + t0 * d.getZ();
if (xx * xx + zz * zz <= radius0 * radius0 && t0 < t && t0 >= 0) {
isect = true;
t = t0;
n = objectToWorld.multiplyDirection(new Vec3D(0, 1, 0));
}
}
}
if (isect) {
normal = n;
return t;
}
return null;
}