public Color GetRadiance(ShadingState state)
{
if (!state.includeSpecular)
return Color.BLACK;
Vector3 reflDir = new Vector3();
Vector3 refrDir = new Vector3();
state.faceforward();
float cos = state.getCosND();
bool inside = state.isBehind();
float neta = inside ? eta : 1.0f / eta;
float dn = 2 * cos;
reflDir.x = (dn * state.getNormal().x) + state.getRay().getDirection().x;
reflDir.y = (dn * state.getNormal().y) + state.getRay().getDirection().y;
reflDir.z = (dn * state.getNormal().z) + state.getRay().getDirection().z;
// refracted ray
float arg = 1 - (neta * neta * (1 - (cos * cos)));
bool tir = arg < 0;
if (tir)
refrDir.x = refrDir.y = refrDir.z = 0;
else
{
float nK = (neta * cos) - (float)Math.Sqrt(arg);
refrDir.x = (neta * state.getRay().dx) + (nK * state.getNormal().x);
refrDir.y = (neta * state.getRay().dy) + (nK * state.getNormal().y);
refrDir.z = (neta * state.getRay().dz) + (nK * state.getNormal().z);
}
// compute Fresnel terms
float cosTheta1 = Vector3.dot(state.getNormal(), reflDir);
float cosTheta2 = -Vector3.dot(state.getNormal(), refrDir);
float pPara = (cosTheta1 - eta * cosTheta2) / (cosTheta1 + eta * cosTheta2);
float pPerp = (eta * cosTheta1 - cosTheta2) / (eta * cosTheta1 + cosTheta2);
float kr = 0.5f * (pPara * pPara + pPerp * pPerp);
float kt = 1 - kr;
Color absorption = null;
if (inside && absorptionDistance > 0)
{
// this ray is inside the object and leaving it
// compute attenuation that occured along the ray
absorption = Color.mul(-state.getRay().getMax() / absorptionDistance, absorptionColor.copy().opposite()).exp();
if (absorption.isBlack())
return Color.BLACK; // nothing goes through
}
// refracted ray
Color ret = Color.black();
if (!tir)
{
ret.madd(kt, state.traceRefraction(new Ray(state.getPoint(), refrDir), 0)).mul(color);
}
if (!inside || tir)
ret.add(Color.mul(kr, state.traceReflection(new Ray(state.getPoint(), reflDir), 0)).mul(color));
return absorption != null ? ret.mul(absorption) : ret;
}
public Color GetRadiance(ShadingState state)
{
if (!state.includeSpecular)
{
return(Color.BLACK);
}
Vector3 reflDir = new Vector3();
Vector3 refrDir = new Vector3();
state.faceforward();
float cos = state.getCosND();
bool inside = state.isBehind();
float neta = inside ? eta : 1.0f / eta;
float dn = 2 * cos;
reflDir.x = (dn * state.getNormal().x) + state.getRay().getDirection().x;
reflDir.y = (dn * state.getNormal().y) + state.getRay().getDirection().y;
reflDir.z = (dn * state.getNormal().z) + state.getRay().getDirection().z;
// refracted ray
float arg = 1 - (neta * neta * (1 - (cos * cos)));
bool tir = arg < 0;
if (tir)
{
refrDir.x = refrDir.y = refrDir.z = 0;
}
else
{
float nK = (neta * cos) - (float)Math.Sqrt(arg);
refrDir.x = (neta * state.getRay().dx) + (nK * state.getNormal().x);
refrDir.y = (neta * state.getRay().dy) + (nK * state.getNormal().y);
refrDir.z = (neta * state.getRay().dz) + (nK * state.getNormal().z);
}
// compute Fresnel terms
float cosTheta1 = Vector3.dot(state.getNormal(), reflDir);
float cosTheta2 = -Vector3.dot(state.getNormal(), refrDir);
float pPara = (cosTheta1 - eta * cosTheta2) / (cosTheta1 + eta * cosTheta2);
float pPerp = (eta * cosTheta1 - cosTheta2) / (eta * cosTheta1 + cosTheta2);
float kr = 0.5f * (pPara * pPara + pPerp * pPerp);
float kt = 1 - kr;
Color absorption = null;
if (inside && absorptionDistance > 0)
{
// this ray is inside the object and leaving it
// compute attenuation that occured along the ray
absorption = Color.mul(-state.getRay().getMax() / absorptionDistance, absorptionColor.copy().opposite()).exp();
if (absorption.isBlack())
{
return(Color.BLACK); // nothing goes through
}
}
// refracted ray
Color ret = Color.black();
if (!tir)
{
ret.madd(kt, state.traceRefraction(new Ray(state.getPoint(), refrDir), 0)).mul(color);
}
if (!inside || tir)
{
ret.add(Color.mul(kr, state.traceReflection(new Ray(state.getPoint(), reflDir), 0)).mul(color));
}
return(absorption != null?ret.mul(absorption) : ret);
}
