public override float GenerateRayDifferential(CameraSample sample, out RayDifferential ray)
{
// Generate raster and camera samples
Point Pras = new Point(sample.ImageX, sample.ImageY, 0);
Point Pcamera = RasterToCamera.TransformPoint(ref Pras);
ray = new RayDifferential(new Point(0, 0, 0), Vector.Normalize((Vector)Pcamera), 0.0f);
// Modify ray for depth of field
if (LensRadius > 0.0f)
{
// Sample point on lens
float lensU, lensV;
MonteCarloUtilities.ConcentricSampleDisk(sample.LensU, sample.LensV, out lensU, out lensV);
lensU *= LensRadius;
lensV *= LensRadius;
// Compute point on plane of focus
float ft = FocalDistance / ray.Direction.Z;
Point Pfocus = ray.Evaluate(ft);
// Update ray for effect of lens
ray.Origin = new Point(lensU, lensV, 0.0f);
ray.Direction = Vector.Normalize(Pfocus - ray.Origin);
}
// Compute offset rays for _PerspectiveCamera_ ray differentials
ray.RxOrigin = ray.RyOrigin = ray.Origin;
ray.RxDirection = Vector.Normalize((Vector)Pcamera + _dxCamera);
ray.RyDirection = Vector.Normalize((Vector)Pcamera + _dyCamera);
ray.Time = sample.Time;
ray = CameraToWorld.TransformRayDifferential(ray);
return(1.0f);
}
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 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);
}
