public void ScatterPhoton(ShadingState state, Color power)
{
Color refr = Color.mul(1 - f0, color);
Color refl = Color.mul(f0, color);
float avgR = refl.getAverage();
float avgT = refr.getAverage();
double rnd = state.getRandom(0, 0, 1);
if (rnd < avgR)
{
state.faceforward();
// don't reflect internally
if (state.isBehind())
return;
// photon is reflected
float cos = state.getCosND();
power.mul(refl).mul(1.0f / avgR);
float dn = 2 * cos;
Vector3 dir = new Vector3();
dir.x = (dn * state.getNormal().x) + state.getRay().getDirection().x;
dir.y = (dn * state.getNormal().y) + state.getRay().getDirection().y;
dir.z = (dn * state.getNormal().z) + state.getRay().getDirection().z;
state.traceReflectionPhoton(new Ray(state.getPoint(), dir), power);
}
else if (rnd < avgR + avgT)
{
state.faceforward();
// photon is refracted
float cos = state.getCosND();
float neta = state.isBehind() ? eta : 1.0f / eta;
power.mul(refr).mul(1.0f / avgT);
float wK = -neta;
float arg = 1 - (neta * neta * (1 - (cos * cos)));
Vector3 dir = new Vector3();
if (state.isBehind() && absorptionDistance > 0)
{
// this ray is inside the object and leaving it
// compute attenuation that occured along the ray
power.mul(Color.mul(-state.getRay().getMax() / absorptionDistance, absorptionColor.copy().opposite()).exp());
}
if (arg < 0)
{
// TIR
float dn = 2 * cos;
dir.x = (dn * state.getNormal().x) + state.getRay().getDirection().x;
dir.y = (dn * state.getNormal().y) + state.getRay().getDirection().y;
dir.z = (dn * state.getNormal().z) + state.getRay().getDirection().z;
state.traceReflectionPhoton(new Ray(state.getPoint(), dir), power);
}
else
{
float nK = (neta * cos) - (float)Math.Sqrt(arg);
dir.x = (-wK * state.getRay().dx) + (nK * state.getNormal().x);
dir.y = (-wK * state.getRay().dy) + (nK * state.getNormal().y);
dir.z = (-wK * state.getRay().dz) + (nK * state.getNormal().z);
state.traceRefractionPhoton(new Ray(state.getPoint(), dir), power);
}
}
}
public void ScatterPhoton(ShadingState state, Color power)
{
Color refr = Color.mul(1 - f0, color);
Color refl = Color.mul(f0, color);
float avgR = refl.getAverage();
float avgT = refr.getAverage();
double rnd = state.getRandom(0, 0, 1);
if (rnd < avgR)
{
state.faceforward();
// don't reflect internally
if (state.isBehind())
{
return;
}
// photon is reflected
float cos = state.getCosND();
power.mul(refl).mul(1.0f / avgR);
float dn = 2 * cos;
Vector3 dir = new Vector3();
dir.x = (dn * state.getNormal().x) + state.getRay().getDirection().x;
dir.y = (dn * state.getNormal().y) + state.getRay().getDirection().y;
dir.z = (dn * state.getNormal().z) + state.getRay().getDirection().z;
state.traceReflectionPhoton(new Ray(state.getPoint(), dir), power);
}
else if (rnd < avgR + avgT)
{
state.faceforward();
// photon is refracted
float cos = state.getCosND();
float neta = state.isBehind() ? eta : 1.0f / eta;
power.mul(refr).mul(1.0f / avgT);
float wK = -neta;
float arg = 1 - (neta * neta * (1 - (cos * cos)));
Vector3 dir = new Vector3();
if (state.isBehind() && absorptionDistance > 0)
{
// this ray is inside the object and leaving it
// compute attenuation that occured along the ray
power.mul(Color.mul(-state.getRay().getMax() / absorptionDistance, absorptionColor.copy().opposite()).exp());
}
if (arg < 0)
{
// TIR
float dn = 2 * cos;
dir.x = (dn * state.getNormal().x) + state.getRay().getDirection().x;
dir.y = (dn * state.getNormal().y) + state.getRay().getDirection().y;
dir.z = (dn * state.getNormal().z) + state.getRay().getDirection().z;
state.traceReflectionPhoton(new Ray(state.getPoint(), dir), power);
}
else
{
float nK = (neta * cos) - (float)Math.Sqrt(arg);
dir.x = (-wK * state.getRay().dx) + (nK * state.getNormal().x);
dir.y = (-wK * state.getRay().dy) + (nK * state.getNormal().y);
dir.z = (-wK * state.getRay().dz) + (nK * state.getNormal().z);
state.traceRefractionPhoton(new Ray(state.getPoint(), dir), power);
}
}
}
