public Vector3D LeALight(Vector3D pointIlluminated, Vector3D normalIlluminated, out Vector3D wi)
{
var random = randomFactory.makeRandom();
var indexLight = (int)(lights.Count * random.NextDouble());
var light = lights[indexLight];
var sampleResult = triangleSampler.sample(light);
var normalLight = light.getNormal(sampleResult.u, sampleResult.v);
var vecR = pointIlluminated - sampleResult.p;
var r = vecR.Length;
var wo = vecR / r;
wi = -wo;
double nearest;
Triangle hitTarget;
Collision collision;
var ray = new Ray(pointIlluminated, wi);
if (!primitives.findNearest(ray, r, out nearest, out hitTarget, out collision) || !light.Equals(hitTarget))
{
return(Constant.BLACK);
}
var le = light.matter.getLe(new Collision(sampleResult.p, wo, normalLight));
var coswo = Vector3D.DotProduct(normalLight, wo);
if (coswo <= Constant.EPSILON)
{
return(Constant.BLACK);
}
return(lights.Count * le * coswo * light.area / (r * r));
}
private Vector3D shadeIndirectTerm(ref Collision collision)
{
var random = randomFactory.makeRandom();
var threthold = rho();
if (random.NextDouble() >= threthold)
{
return(Constant.BLACK);
}
return(shadeDividedRho(collision));
}
public SamplePoint sample(Triangle triangle)
{
var random = randomFactory.makeRandom();
var s = random.NextDouble();
var t = random.NextDouble();
var sqrtT = Math.Sqrt(t);
var u = sqrtT * (1 - s);
var v = s * sqrtT;
var p = (1 - sqrtT) * triangle.a.position + u * triangle.b.position + v * triangle.c.position;
return(new SamplePoint(p, u, v));
}
public Vector3D sample(IRandomFactory randomFactory)
{
double rand1, rand2;
var randomer = randomFactory.makeRandom();
rand1 = randomer.NextDouble();
rand2 = randomer.NextDouble();
double cosPhi = Math.Cos(2.0 * Math.PI * rand1);
double sinPhi = Math.Sin(2.0 * Math.PI * rand1);
double cosTheta2 = 1.0 - rand2;
double cosTheta = Math.Sqrt(cosTheta2);
double sinTheta = Math.Sqrt(1.0 - cosTheta2);
var u = sinTheta * cosPhi;
var v = sinTheta * sinPhi;
var w = cosTheta;
return(new Vector3D(u, v, w));
}
