public Color trace(Scene scene) {
// find first intersection point with scene objects
Hit firstHit = scene.intersect(this);
// calculate light intensity/color at hit point
if (firstHit == null) {
return new Color(0, 0, 0);
}
Material material = firstHit.getShape().getMaterial();
Color result = new Color(0, 0, 0);
result = result.add(material.computeAmbient(scene.getAmbientLight()));
for (LightSource light : scene.getLightSources()) {
Vector direction = light.getPosition().sub(firstHit.getIntersectionPoint()).normalize();
Vector offset = direction.mult(OFFSET);
Ray shadowRay =
new Ray(direction, firstHit.getIntersectionPoint().add(offset), recursionDepth);
Hit intersection = scene.intersect(shadowRay);
if (intersection == null) {
result = result.add(material.computeDiffuseLight(firstHit, light));
result = result.add(material.computeSpecularLight(firstHit, light));
}
}
if (recursionDepth > 0) {
float n1 = material.getRefractionMediumOutside();
float n2 = material.getRefractionMediumInside();
float reflectionAbility = 1;
if (n1 > 0 && n2 > 0) {
Refraction refractionIn = getRefraction(direction, firstHit.getNormal(), n1, n2);
if (refractionIn != null) {
reflectionAbility = refractionIn.reflectionAbility;
Vector offset = refractionIn.direction.mult(OFFSET);
Ray refractionRay =
new Ray(
refractionIn.direction,
firstHit.getIntersectionPoint().add(offset),
recursionDepth);
Hit outHit = scene.intersect(refractionRay);
Refraction refractionOut =
getRefraction(refractionRay.direction, outHit.getNormal().mult(-1), n2, n1);
if (refractionOut != null) {
Ray outRay =
new Ray(
refractionOut.direction,
outHit.getIntersectionPoint().add(refractionOut.direction.mult(OFFSET)),
recursionDepth - 1);
result = result.add(outRay.trace(scene).modulate(refractionIn.transmissionAbility));
}
}
}
if (material.getReflectionCo() > 0) {
Vector direction = getReflection(this.direction, firstHit.getNormal());
Vector offset = direction.mult(OFFSET);
Ray reflectionRay =
new Ray(direction, firstHit.getIntersectionPoint().add(offset), recursionDepth - 1);
result =
result.add(
reflectionRay
.trace(scene)
.modulate(material.getReflectionCo() * reflectionAbility));
}
}
return result;
}
