public override Spectrum f(Vector3 wo, Vector3 wi)
{
double a = 1 - ((roughness2 / 2 * (roughness2 + 0.33)));
double b = 0.45 * roughness2 / (roughness2 + 0.09);
double sinThetaI = Utils.SinTheta(wi);
double sinThetaO = Utils.SinTheta(wo);
double sinAlpha;
double tanBeta;
if (Utils.AbsCosTheta(wi) > Utils.AbsCosTheta(wo))
{
sinAlpha = sinThetaO;
tanBeta = sinThetaI / Utils.AbsCosTheta(wi);
}
else
{
sinAlpha = sinThetaI;
tanBeta = sinThetaO / Utils.AbsCosTheta(wo);
}
double maxCos = 0;
if (sinThetaI > 1e-4 && sinThetaO > 1e-4)
{
double dCos = Utils.CosPhi(wi) * Utils.CosPhi(wo) + Utils.SinPhi(wi) * Utils.SinPhi(wo);
maxCos = Math.Max(0, dCos);
}
Spectrum nnn = (kd / Math.PI) * (a + b * maxCos * sinAlpha * tanBeta);
return(nnn);
}
public override Spectrum f(Vector3 wo, Vector3 wi)
{
if (!Utils.SameHemisphere(wo, wi))
{
return(Spectrum.ZeroSpectrum);
}
// Cos term
// Adicijski izrek: cos(x +- y) = cos(x) * cos(y) -+ sin(x) * sin(y)
double cosDiff = Utils.CosPhi(wi) * Utils.CosPhi(wo) + Utils.SinPhi(wi) * Utils.SinPhi(wo);
// Sin and tan terms
double sinAlpha, tanBeta;
if (Utils.AbsCosTheta(wi) > Utils.AbsCosTheta(wo)) // oTheta > iTheta
{
sinAlpha = Utils.SinTheta(wo);
tanBeta = Utils.SinTheta(wi) / Utils.AbsCosTheta(wi);
}
else // iTheta >= oTheta
{
sinAlpha = Utils.SinTheta(wi);
tanBeta = Utils.SinTheta(wo) / Utils.AbsCosTheta(wo);
}
return(kd * Utils.PiInv * (A + B * Math.Max(0, cosDiff) * sinAlpha * tanBeta));
}
/// <summary>
/// Sample returns a single possible direction
/// </summary>
/// <param name="woL"></param>
/// <returns></returns>
public override (Spectrum, Vector3, double) Sample_f(Vector3 wo)
{
var F = fresnel.Evaluate(Utils.CosTheta(wo));
bool entering = Utils.CosTheta(wo) > 0;
var etaI = entering ? fresnel.EtaI : fresnel.EtaT;
var etaT = entering ? fresnel.EtaT : fresnel.EtaI;
var n = new Vector3(0, 0, 1);
n = Vector3.Dot(n, wo) < 0 ? -n : n;
var(refracted, wt) = Refract(wo, n, etaI / etaT);
if (!refracted)
{
return(Spectrum.ZeroSpectrum, null, 0);
}
Spectrum ft = r * (1 - F.Max());
var pdf = 1 - F.Max();
return(ft / Utils.AbsCosTheta(wt), wt, pdf);
}
/// <summary>
/// Sample returns a single possible direction
/// </summary>
/// <param name="woL"></param>
/// <returns></returns>
public override (Spectrum, Vector3, double) Sample_f(Vector3 woL)
{
// perfect specular reflection
Vector3 wiL = new Vector3(-woL.x, -woL.y, woL.z);
Spectrum ft = r * fresnel.Evaluate(Utils.CosTheta(wiL));
return(ft / Utils.AbsCosTheta(wiL), wiL, 1);
}
public override Spectrum f(Vector3 wo, Vector3 wi)
{
// var phiWi = Phi(wi.x, wi.y);
// var phiWo = Phi(wo.x, wo.y);
// var thetaWi = Theta(wi.x, wi.y, wi.z);
// var thetaWo = Theta(wo.x, wo.y, wo.z);
//
// var alpha = Math.Max(thetaWi, thetaWo);
// var beta = Math.Min(thetaWi, thetaWo);
//
// return kd * Utils.PiInv * (a + b * Math.Max(0, Math.Cos(phiWi - phiWo))) * Math.Sin(alpha) * Math.Tan(beta);
var sinThetaI = Utils.SinTheta(wi);
var sinThetaO = Utils.SinTheta(wo);
var maxCos = 0.0;
if (sinThetaI > 1e-4 && sinThetaO > 1e-4)
{
var sinPhiI = Utils.SinPhi(wi);
var cosPhiI = Utils.CosPhi(wi);
var sinPhiO = Utils.SinPhi(wo);
var cosPhiO = Utils.CosPhi(wo);
var dCos = cosPhiI * cosPhiO + sinPhiI * sinPhiO;
maxCos = Math.Max(0, dCos);
}
double sinAlpha;
double tanBeta;
if (Utils.AbsCosTheta(wi) > Utils.AbsCosTheta(wo))
{
sinAlpha = sinThetaO;
tanBeta = sinThetaI / Utils.AbsCosTheta(wi);
}
else
{
sinAlpha = sinThetaI;
tanBeta = sinThetaO / Utils.AbsCosTheta(wo);
}
return(kd * Utils.PiInv * (a + b * maxCos * sinAlpha * tanBeta));
}
public Spectrum Li(Ray r, Scene s)
{
/* BASIC Implement
repeat
r <- random ray from camera
L <- 0, β <- 1, nbounces <- 0
repeat
isect <- intersect r with scene
if isect == null // no hit
break
wo <- -r
if isect == light // light hit
L<- β*Le(wo) // add light emitted
break
wi <- random ray from isect
(f,pr) <- bsdf(isect,wi,wo)
β <- β*f*|cosθ|/pr
r <- wi
nbounces <- nbounces+1
AddSampleToImage(L,r)
*/
/* Russian Roulette Implement
(f,pr) <- bsdf(isect,wi,wo)
β <- β*f*|cosθ|/pr
r <- wi
if nbounces>3
q <- 1 - max(β)
if random() < q
break
β <- β/(1-q)
*/
var L = Spectrum.ZeroSpectrum;
var beta = Spectrum.Create((double)1);
int nbounces = 0;
double q;
while(nbounces < 20) {
(double? mint, SurfaceInteraction si) = s.Intersect(r);
// If nothing hit end
if (si == null) {
break;
}
// If Light hit include it and finish
if (si.Obj is Light) {
if (nbounces == 0)
{
L = beta * si.Le(si.Wo);
//Console.WriteLine(beta.c);
//Console.WriteLine(L.c);
}
break;
}
// Sample light from SurfaceInteraction
// TODO
Spectrum Ld = Light.UniformSampleOneLight(si, s);
L = L.AddTo(beta * Ld);
// Make new reflected Ray
//Ray wi = si.SpawnRay(UniformSampleSphere());
// Get BSDF of hit object
(Spectrum f, Vector3 wi, double pr, bool p) = (si.Obj as Shape).BSDF.Sample_f(si.Wo, si);
// Update beta
beta = beta * f * Utils.AbsCosTheta(wi) / pr;
// Set reflected Ray as original Ray
r = new Ray(si.Point, wi);
if (nbounces > 3) {
q = 1 - beta.Max();
if (ThreadSafeRandom.NextDouble() < q) {
break;
}
beta /= (1 - q);
}
nbounces += 1;
}
Console.WriteLine(L.c);
return L;
}
public Spectrum Li(Ray r, Scene s)
{
Spectrum L = Spectrum.ZeroSpectrum;
Spectrum B = Spectrum.Create(1);
int nbounces = 0;
while (nbounces < 20)
{
SurfaceInteraction isect = null;
//Get the object the ray intersected with
isect = s.Intersect(r).Item2;
//If the ray hasn't hit anything return 0
if (isect == null)
{
break;
}
Vector3 wo = isect.Wo;//-r.d;
//If the ray hit a light, take its emission
if (isect.Obj is Light)
{
if (nbounces == 0)
{
L = B * isect.Le(wo);
}
break;
}
//Create a light ray from the intersection point and add its emission
Spectrum Ld = Light.UniformSampleOneLight(isect, s);
L = L.AddTo(B * Ld);
//Get the materials value at this point
(Spectrum f, Vector3 wi, double pr, bool specular) = (isect.Obj as Shape).BSDF.Sample_f(wo, isect);
if (!specular)
{
B = B * f * Utils.AbsCosTheta(wi) / pr;
}
//Spawn a new ray from the intersection
r = isect.SpawnRay(wi);
if (nbounces > 3)
{
double q = 1.0 - B.Max();
if (ThreadSafeRandom.NextDouble() < q)
{
break;
}
B = B / (1 - q);
}
nbounces++;
}
return(L);
}
public override double Pdf(Vector3 wo, Vector3 wi)
{
//return Utils.CosTheta(wi) * Utils.PiInv;
//return !Utils.SameHemisphere(wo, wi) ? Utils.AbsCosTheta(wi) * Utils.PiInv : 0;
return(Utils.AbsCosTheta(wi) * Utils.PiInv);
}