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 Spectrum SampleL(Point p, float pEpsilon, LightSample ls,
float time, out Vector wi, out float pdf,
out VisibilityTester vis)
{
wi = _direction;
pdf = 1.0f;
vis = new VisibilityTester(p, pEpsilon, wi, time);
return _radiance;
}
public override Spectrum SampleL(
Point p, float pEpsilon, LightSample ls, float time, out Vector wi,
out float pdf, out VisibilityTester vis)
{
wi = Vector.Normalize(_lightPosition - p);
pdf = 1.0f;
vis = new VisibilityTester(p, pEpsilon, _lightPosition, 0.0f, time);
return _intensity / Point.DistanceSquared(_lightPosition, p);
}
public Point TransformPoint(ref Point pt)
{
float x = pt.X, y = pt.Y, z = pt.Z;
float xp = _m.M[0, 0] * x + _m.M[0, 1] * y + _m.M[0, 2] * z + _m.M[0, 3];
float yp = _m.M[1, 0] * x + _m.M[1, 1] * y + _m.M[1, 2] * z + _m.M[1, 3];
float zp = _m.M[2, 0] * x + _m.M[2, 1] * y + _m.M[2, 2] * z + _m.M[2, 3];
float wp = _m.M[3, 0] * x + _m.M[3, 1] * y + _m.M[3, 2] * z + _m.M[3, 3];
Debug.Assert(wp != 0);
if (wp == 1.0f)
return new Point(xp, yp, zp);
return new Point(xp, yp, zp) / wp;
}
public override Spectrum L(Point p, Normal n, Vector w)
{
throw new System.NotImplementedException();
}
public override float Pdf(Point p, Vector wi)
{
throw new System.NotImplementedException();
}
public override Spectrum SampleL(Point p, float pEpsilon, LightSample ls, float time, out Vector wi, out float pdf,
out VisibilityTester vis)
{
throw new System.NotImplementedException();
}
public abstract Spectrum L(Point p, Normal n, Vector w);
public override float Pdf(Point p, Vector wi)
{
return 0.0f;
}
public PointLight(Transform lightToWorld, Spectrum intensity)
: base(lightToWorld)
{
_intensity = intensity;
_lightPosition = lightToWorld.TransformPoint(Point.Zero);
}
public Point TransformPoint(Point pt)
{
return TransformPoint(ref pt);
}
public static Transform LookAt(Point pos, Point look, Vector up)
{
var m = new float[4, 4];
// Initialize fourth column of viewing matrix
m[0, 3] = pos.X;
m[1, 3] = pos.Y;
m[2, 3] = pos.Z;
m[3, 3] = 1;
// Initialize first three columns of viewing matrix
Vector dir = Vector.Normalize(look - pos);
Vector left = Vector.Normalize(Vector.Cross(Vector.Normalize(up), dir));
Vector newUp = Vector.Cross(dir, left);
m[0, 0] = left.X;
m[1, 0] = left.Y;
m[2, 0] = left.Z;
m[3, 0] = 0.0f;
m[0, 1] = newUp.X;
m[1, 1] = newUp.Y;
m[2, 1] = newUp.Z;
m[3, 1] = 0.0f;
m[0, 2] = dir.X;
m[1, 2] = dir.Y;
m[2, 2] = dir.Z;
m[3, 2] = 0.0f;
var camToWorld = new Matrix4x4(m);
return new Transform(Matrix4x4.Invert(camToWorld), camToWorld);
}