/// <summary>
/// Metoda koja pomocu pracenja zrake racuna boju u tocki presjeka. Racuna se
/// osvjetljenje u tocki presjeka te se zbraja s doprinosima osvjetljenja koje
/// donosi reflektirana i refraktirana zraka.
/// </summary>
/// <param name="ray">pracena zraka</param>
/// <param name="depth">dubina rekurzije</param>
/// <returns>vektor boje u tocki presjeka</returns>
public ColorVector traceRay(Ray ray, int depth)
{
ColorVector Clocal = backgroundColors;
ColorVector C = new ColorVector(0, 0, 0);
int tocka_najblizeg_presjeka = -1;
bool presjek = false;
if (depth > MAXDEPTH)
{
C = new ColorVector(0, 0, 0);
return(C);
}
else
{
for (int i = 0; i < this.numberOfObjects; i++)
{
if (sphere[i].intersection(ray))
{
presjek = true;
if (tocka_najblizeg_presjeka == -1)
{
tocka_najblizeg_presjeka = i;
}
if (ray.getStartingPoint().getDistanceFrom(sphere[tocka_najblizeg_presjeka].getIntersectionPoint()) > ray.getStartingPoint().getDistanceFrom(sphere[i].getIntersectionPoint()))
{
tocka_najblizeg_presjeka = i;
}
}
}
if (presjek)
{
PropertyVector ambijetalniKoef = sphere[tocka_najblizeg_presjeka].getKa();
double r, g, b, pom;
r = ambientLight.getRed() * ambijetalniKoef.getRedParameter();
g = ambientLight.getGreen() * ambijetalniKoef.getGreenParameter();
b = ambientLight.getBlue() * ambijetalniKoef.getBlueParameter();
Clocal = new ColorVector((float)r, (float)g, (float)b);
Point najblizatocka = sphere[tocka_najblizeg_presjeka].getIntersectionPoint();
PropertyVector difuzniKoef = sphere[tocka_najblizeg_presjeka].getKd();
Vector L = new Vector(najblizatocka, lightPosition);
Vector N = sphere[tocka_najblizeg_presjeka].getNormal(najblizatocka);
Vector V = new Vector(najblizatocka, ray.getStartingPoint());
Vector R = L.getReflectedVector(N);
V.normalize();
R.normalize();
L.normalize();
double ni = sphere[tocka_najblizeg_presjeka].getNi();
double vn = V.dotProduct(N);
if (vn < 0)
{
N = N.multiple(-1);
ni = 1.0 / ni;
}
bool sjena = shadow(najblizatocka);
if ((pom = L.dotProduct(N)) > 0 && !sjena)
{
r = light.getRed() * difuzniKoef.getRedParameter() * pom;
g = light.getGreen() * difuzniKoef.getGreenParameter() * pom;
b = light.getBlue() * difuzniKoef.getBlueParameter() * pom;
ColorVector Cdifuzno = new ColorVector((float)r, (float)g, (float)b);
Clocal = Clocal.add(Cdifuzno);
}
PropertyVector spekularniKoef = sphere[tocka_najblizeg_presjeka].getKs();
if ((pom = R.dotProduct(V)) > 0 && !sjena)
{
r = light.getRed() * spekularniKoef.getRedParameter() * Math.Pow(pom, sphere[tocka_najblizeg_presjeka].getN());
g = light.getGreen() * spekularniKoef.getGreenParameter() * Math.Pow(pom, sphere[tocka_najblizeg_presjeka].getN());
b = light.getBlue() * spekularniKoef.getBlueParameter() * Math.Pow(pom, sphere[tocka_najblizeg_presjeka].getN());
ColorVector Cspekularno = new ColorVector((float)r, (float)g, (float)b);
Clocal = Clocal.add(Cspekularno);
}
Vector ReflektiraniV = V.getReflectedVector(N);
ReflektiraniV.normalize();
Ray Rrefl = new Ray(najblizatocka, ReflektiraniV);
ColorVector Crefl = traceRay(Rrefl, depth + 1);
Vector U = V.getRefractedVector(N, ni);
U.normalize();
Ray Rrefr = new Ray(najblizatocka, U);
ColorVector Crefr = traceRay(Rrefr, depth + 1);
C = C.add(Clocal);
C = C.add(Crefl.multiple(sphere[tocka_najblizeg_presjeka].getReflectionFactor()));
C = C.add(Crefr.multiple(sphere[tocka_najblizeg_presjeka].getRefractionFactor()));
C.correct();
return(C);
}
else
{
return(C = new ColorVector(backgroundColors.getRed(), backgroundColors.getBlue(), backgroundColors.getGreen()));
}
}
}
/// <summary>
/// Sluzi za mnozenje vektora boje s vektorom koeficijenata. Koristi se kod
/// odredivanja boje lokalnog osvjetljenja.
/// </summary>
/// <param name="c">vektor koeficijenata s kojim se mnozi</param>
/// <returns>vektor boje koji je rezultat mnozenja vektora boje s vektorom koeficijenata</returns>
public ColorVector multiple(PropertyVector c)
{
return(new ColorVector(c.getRedParameter() * red, c.getGreenParameter() * green,
c.getBlueParameter() * blue));
}
