public override Spectrum SampleL(Scene scene, LightSample ls, float u1, float u2, float time, out Ray ray, out Normal ns, out float pdf)
{
ray = new Ray(_lightPosition,
MonteCarloUtilities.UniformSampleSphere(ls.UPos0, ls.UPos1),
0.0f, float.PositiveInfinity, time);
ns = (Normal) ray.Direction;
pdf = MonteCarloUtilities.UniformSpherePdf();
return _intensity;
}
public static Vector Cross(Normal v1, Vector v2)
{
float v1x = v1.X, v1y = v1.Y, v1z = v1.Z;
float v2x = v2.X, v2y = v2.Y, v2z = v2.Z;
return new Vector(
(v1y * v2z) - (v1z * v2y),
(v1z * v2x) - (v1x * v2z),
(v1x * v2y) - (v1y * v2x));
}
public Bsdf(DifferentialGeometry dgShading, Normal nGeom, float eta = 1.0f)
{
_dgShading = dgShading;
_ng = nGeom;
_eta = eta;
_nn = dgShading.Normal;
_sn = Vector.Normalize(dgShading.DpDu);
_tn = Normal.Cross(_nn, _sn);
_bxdfs = new List<Bxdf>();
}
public DifferentialGeometry(Point point, Vector dpdu, Vector dpdv,
Normal dndu, Normal dndv, float u, float v, Shape shape)
{
Point = point;
Normal = (Normal) Vector.Normalize(Vector.Cross(dpdu, dpdv));
DpDu = dpdu;
DpDv = dpdv;
DnDu = dndu;
DnDv = dndv;
U = u;
V = v;
Shape = shape;
if (shape != null && shape.ReverseOrientation != shape.TransformSwapsHandedness)
Normal *= -1.0f;
}
public override Spectrum SampleL(Scene scene, LightSample ls, float u1, float u2, float time, out Ray ray, out Normal ns, out float pdf)
{
// Choose point on disk oriented toward infinite light direction
Point worldCenter;
float worldRadius;
scene.WorldBound.BoundingSphere(out worldCenter, out worldRadius);
Vector v1, v2;
Vector.CoordinateSystem(_direction, out v1, out v2);
float d1, d2;
MonteCarloUtilities.ConcentricSampleDisk(ls.UPos0, ls.UPos1, out d1, out d2);
Point Pdisk = worldCenter + worldRadius * (d1 * v1 + d2 * v2);
// Set ray origin and direction for infinite light ray
ray = new Ray(Pdisk + worldRadius * _direction, -_direction, 0.0f, float.PositiveInfinity, time);
ns = (Normal) ray.Direction;
pdf = 1.0f / (MathUtility.Pi * worldRadius * worldRadius);
return _radiance;
}
public override Point Sample(float u1, float u2, out Normal ns)
{
var p = new Point();
MonteCarloUtilities.ConcentricSampleDisk(u1, u2, out p.X, out p.Y);
p.X *= _radius;
p.Y *= _radius;
p.Z = _height;
ns = Normal.Normalize(ObjectToWorld.TransformNormal(new Normal(0, 0, 1)));
if (ReverseOrientation)
ns *= -1.0f;
return ObjectToWorld.TransformPoint(ref p);
}
public static float Dot(Vector v1, Normal v2)
{
return v1.X * v2.X + v1.Y * v2.Y + v1.Z * v2.Z;
}
public override Point Sample(Point p, float u1, float u2, out Normal ns)
{
// Compute coordinate system for sphere sampling
Point Pcenter = ObjectToWorld.TransformPoint(Point.Zero);
Vector wc = Vector.Normalize(Pcenter - p);
Vector wcX, wcY;
Vector.CoordinateSystem(wc, out wcX, out wcY);
// Sample uniformly on sphere if $\pt{}$ is inside it
if (Point.DistanceSquared(p, Pcenter) - _radius * _radius < 1e-4f)
return Sample(u1, u2, out ns);
// Sample sphere uniformly inside subtended cone
float sinThetaMax2 = _radius * _radius / Point.DistanceSquared(p, Pcenter);
float cosThetaMax = MathUtility.Sqrt(Math.Max(0.0f, 1.0f - sinThetaMax2));
DifferentialGeometry dgSphere;
float thit, rayEpsilon;
Point ps;
Ray r = new Ray(p, MonteCarloUtilities.UniformSampleCone(u1, u2, cosThetaMax, ref wcX, ref wcY, ref wc),
1e-3f);
if (!TryIntersect(r, out thit, out rayEpsilon, out dgSphere))
thit = Vector.Dot(Pcenter - p, Vector.Normalize(r.Direction));
ps = r.Evaluate(thit);
ns = (Normal) Vector.Normalize(ps - Pcenter);
if (ReverseOrientation)
ns *= -1.0f;
return ps;
}
public override Spectrum SampleL(Scene scene, LightSample ls, float u1, float u2, float time, out Ray ray, out Normal ns, out float pdf)
{
throw new System.NotImplementedException();
}
public static Normal FaceForward(Normal n, Normal v)
{
return (Dot(n, v) < 0.0f) ? -n : n;
}
public static float Dot(Normal n1, Normal n2)
{
return n1.X * n2.X + n1.Y * n2.Y + n1.Z * n2.Z;
}
public virtual Point Sample(Point p, float u1, float u2, out Normal ns)
{
return Sample(u1, u2, out ns);
}
public virtual Point Sample(float u1, float u2, out Normal ns)
{
throw new InvalidOperationException("Unimplemented Shape.Sample() method called.");
}
public Normal TransformNormal(ref Normal n)
{
float x = n.X, y = n.Y, z = n.Z;
return new Normal(
_mInv.M[0, 0] * x + _mInv.M[1, 0] * y + _mInv.M[2, 0] * z,
_mInv.M[0, 1] * x + _mInv.M[1, 1] * y + _mInv.M[2, 1] * z,
_mInv.M[0, 2] * x + _mInv.M[1, 2] * y + _mInv.M[2, 2] * z);
}
public Normal TransformNormal(Normal n)
{
return TransformNormal(ref n);
}
public static Normal Normalize(Normal n)
{
return n / n.Length();
}
public abstract Spectrum SampleL(Scene scene, LightSample ls, float u1, float u2,
float time, out Ray ray, out Normal ns, out float pdf);
public static float AbsDot(Normal v1, Normal v2)
{
return Math.Abs(Dot(v1, v2));
}
public abstract Spectrum L(Point p, Normal n, Vector w);
public override Point Sample(float u1, float u2, out Normal ns)
{
var z = MathUtility.Lerp(u1, _zMin, _zMax);
var t = u2 * _phiMax;
var p = new Point(_radius * MathUtility.Cos(t), _radius * MathUtility.Sin(t), z);
ns = Normal.Normalize(ObjectToWorld.TransformNormal(new Normal(p.X, p.Y, 0)));
if (ReverseOrientation)
ns *= -1.0f;
return ObjectToWorld.TransformPoint(ref p);
}
public static Vector FaceForward(Vector n, Normal v)
{
return (Dot(n, v) < 0.0f) ? -n : n;
}
public override Spectrum L(Point p, Normal n, Vector w)
{
throw new System.NotImplementedException();
}
public override Point Sample(float u1, float u2, out Normal ns)
{
Point p = new Point(0, 0, 0) + _radius * MonteCarloUtilities.UniformSampleSphere(u1, u2);
ns = Normal.Normalize(ObjectToWorld.TransformNormal(new Normal(p.X, p.Y, p.Z)));
if (ReverseOrientation)
ns *= -1.0f;
return ObjectToWorld.TransformPoint(ref p);
}
