private void PhotonShade(HitInfo hit, Line ray, int threadId, int depth, bool inside, ColorIntensity lightCol, Random rnd, double distance, double area)
{
if (depth > maxrecurse)
return;
if (lightCol.GreyScale() < minratio)
return;
RealHitInfo realHit = hit.GetReal(ray);
Material surf = realHit.HitStuff;
ColorIntensity pigment = realHit.Pigment.GetTexture(realHit.Normal, 0);
double dist = realHit.Normal.Start.LineTo(ray.Start).Length;
distance += dist;
if (surf.Attenutive && inside)
{
lightCol.R *= Math.Exp(-(1.0 - surf.Attenuation[0]) * dist / surf.AttenuationDistance);
lightCol.G *= Math.Exp(-(1.0 - surf.Attenuation[1]) * dist / surf.AttenuationDistance);
lightCol.B *= Math.Exp(-(1.0 - surf.Attenuation[2]) * dist / surf.AttenuationDistance);
}
#if DEBUG
Photon currentParent = PhotonParents[threadId];
#endif
if ((depth > 0 || allLightsArePhotons))
{
Photon photon = new Photon();
photon.HitPos.X = (float)realHit.Normal.Start.X;
photon.HitPos.Y = (float)realHit.Normal.Start.Y;
photon.HitPos.Z = (float)realHit.Normal.Start.Z;
photon.TravelDir.Dx = (float)ray.Direct.Dx;
photon.TravelDir.Dy = (float)ray.Direct.Dy;
photon.TravelDir.Dz = (float)ray.Direct.Dz;
ColorIntensity photonColor = lightCol;
if (realLighting || distance == double.PositiveInfinity)
{
photonColor.R *= area / PhotonCount;
photonColor.G *= area / PhotonCount;
photonColor.B *= area / PhotonCount;
}
else
{
photonColor.R *= distance * distance * area / PhotonCount;
photonColor.G *= distance * distance * area / PhotonCount;
photonColor.B *= distance * distance * area / PhotonCount;
}
photon.PhotonColorPower.R = (float)photonColor.R;
photon.PhotonColorPower.G = (float)photonColor.G;
photon.PhotonColorPower.B = (float)photonColor.B;
#if DEBUG
photon.parent = currentParent;
PhotonParents[threadId] = photon;
#endif
Map.AddPhoton(photon, threadId);
}
ColorIntensity reflectance = new ColorIntensity();
ColorIntensity transmitance = new ColorIntensity();
Line refractRay = new Line();
Line reflectRay = new Line();
if (surf.Refractive || surf.Reflective)
{
ray.Direct = ray.Direct.Scale(1 / ray.Direct.Length);
reflectance.R = surf.Reflective ? surf.Reflectance[0] : 0.0;
reflectance.G = surf.Reflective ? surf.Reflectance[1] : 0.0;
reflectance.B = surf.Reflective ? surf.Reflectance[2] : 0.0;
if (surf.Refractive)
{
double ni = inside ? surf.RefractIndex : 1.0;
double nt = (!inside) ? surf.RefractIndex : 1.0;
double cratio = ni / nt;
double ct1 = -ray.Direct.Dot(realHit.Normal.Direct);
double ct2sqrd = 1 - cratio * cratio * (1 - ct1 * ct1);
if (ct2sqrd <= 0)
{
reflectance.R = 1;
reflectance.G = 1;
reflectance.B = 1;
}
else
{
double ct2 = Math.Sqrt(ct2sqrd);
// fresnel equations for reflectance perp and parallel.
double rperp = (ni * ct1 - nt * ct2) / (ni * ct1 + nt * ct2);
double rpll = (nt * ct1 - ni * ct2) / (ni * ct2 + nt + ct1);
// assume unpolarised light always - better then tracing 2
// rays for both sides of every interface.
double reflectanceval = (rperp * rperp + rpll * rpll) / 2;
reflectance.R = Math.Min(1.0, reflectance.R + reflectanceval);
reflectance.G = Math.Min(1.0, reflectance.G + reflectanceval);
reflectance.B = Math.Min(1.0, reflectance.B + reflectanceval);
transmitance.R = 1 - reflectance.R;
transmitance.G = 1 - reflectance.G;
transmitance.B = 1 - reflectance.B;
refractRay.Direct = ray.Direct.Scale(cratio);
refractRay.Direct.Add(realHit.Normal.Direct.Scale(cratio * (ct1) - ct2));
refractRay.Start = realHit.Normal.Start.MoveBy(refractRay.Direct.Scale(EPSILON * 10));
}
}
reflectRay.Direct = new Vector(ray.Direct.Dx, ray.Direct.Dy, ray.Direct.Dz);
reflectRay.Direct.Add(realHit.Normal.Direct.Scale(-2 * ray.Direct.Dot(realHit.Normal.Direct)));
reflectRay.Start = realHit.Normal.Start.MoveBy(reflectRay.Direct.Scale(EPSILON * 10));
}
bool doReflect = false;
bool doRefract = false;
bool doDifuse = false;
double avr = reflectance.R + reflectance.G + reflectance.B;
avr /= 3;
double avt = transmitance.R + transmitance.G + transmitance.B;
avt /= 3;
double reflectWeight = Math.Max(avr, 0.0);
double refractWeight = Math.Max(avt, 0.0);
double diffuseWeight = Math.Max(pigment.GreyScale() * surf.Diffuse, 0.0);
double specularity = 1.0;
double diffusivity = 1.0;
if (surf.Refractive)
{
specularity = surf.Specularity;
diffusivity = 1.0 - specularity;
reflectWeight *= surf.Specularity;
refractWeight *= surf.Specularity;
diffuseWeight *= 1.0-surf.Specularity;
}
double choice = rnd.NextDouble();
if (choice < diffuseWeight)
doDifuse = true;
else if (choice < diffuseWeight+reflectWeight)
doReflect = true;
else if (choice < diffuseWeight+reflectWeight+refractWeight)
doRefract = true;
if (doRefract && avt > minratio)
{
SetIn(ref refractRay.Start, threadId);
HitInfo hitnew = scene.Intersect(refractRay, threadId);
if (!(hitnew.HitDist == -1))
{
ColorIntensity lightCol2 = new ColorIntensity();
lightCol2.R = lightCol.R * transmitance.R *specularity/ refractWeight;
lightCol2.G = lightCol.G * transmitance.G * specularity / refractWeight;
lightCol2.B = lightCol.B * transmitance.B * specularity / refractWeight;
PhotonShade(hitnew, refractRay, threadId, depth + 1, !inside, lightCol2, rnd, distance, area);
}
}
if (doReflect && avr > minratio)
{
SetIn(ref reflectRay.Start, threadId);
HitInfo hitnew2 = scene.Intersect(reflectRay, threadId);
if (!(hitnew2.HitDist == -1))
{
ColorIntensity lightCol2 = new ColorIntensity();
lightCol2.R = lightCol.R * reflectance.R * specularity / reflectWeight;
lightCol2.G = lightCol.G * reflectance.G * specularity / reflectWeight;
lightCol2.B = lightCol.B * reflectance.B * specularity / reflectWeight;
PhotonShade(hitnew2, reflectRay, threadId, depth + 1, inside, lightCol2, rnd, distance, area);
}
}
if (doDifuse)
{
double z = rnd.NextDouble();
double theta = rnd.NextDouble() * 2.0 * Math.PI;
double r = Math.Sqrt(1 - z * z);
double x = Math.Cos(theta) * r;
double y = Math.Sin(theta) * r;
Line diffuseRay = new Line();
Vector a;
Vector b;
Vector basis = realHit.Normal.Direct.Scale(1.0/realHit.Normal.Direct.Length);
GetPerp(basis, out a, out b);
diffuseRay.Direct = basis.Scale(z);
diffuseRay.Direct.Add(a.Scale(x/a.Length));
diffuseRay.Direct.Add(b.Scale(y/b.Length));
diffuseRay.Start = realHit.Normal.Start.MoveBy(diffuseRay.Direct.Scale(EPSILON * 10));
SetIn(ref diffuseRay.Start, threadId);
HitInfo hitnew2 = scene.Intersect(diffuseRay, threadId);
if (!(hitnew2.HitDist == -1))
{
ColorIntensity lightCol2 = new ColorIntensity();
lightCol2.R = lightCol.R * surf.Diffuse * pigment.R *diffusivity/ diffuseWeight;
lightCol2.G = lightCol.G * surf.Diffuse * pigment.G * diffusivity / diffuseWeight;
lightCol2.B = lightCol.B * surf.Diffuse * pigment.B * diffusivity / diffuseWeight;
PhotonShade(hitnew2, diffuseRay, threadId, depth + 1, inside, lightCol2, rnd, distance, area);
}
}
#if DEBUG
PhotonParents[threadId] = currentParent;
#endif
}
