public virtual double GenerateRayDifferential(CameraSample sample, out RayDifferential rd)
{
double wt = GenerateRay(sample, out Ray r);
rd = new RayDifferential(r);
if (wt == 0.0)
{
return(0.0);
}
// Find camera ray after shifting a fraction of a pixel in the $x$ direction
double wtx = 0.0;
foreach (double eps in new List <double> {
0.5, -0.5
})
{
CameraSample sshift = sample;
sshift.FilmPoint = new Point2D(sshift.FilmPoint.X + eps, sshift.FilmPoint.Y);
wtx = GenerateRay(sshift, out Ray rx);
rd.RxOrigin = rd.Origin + (rx.Origin - rd.Origin) / eps;
rd.RxDirection = rd.Direction + (rx.Direction - rd.Direction) / eps;
if (wtx != 0.0)
{
break;
}
}
if (wtx == 0.0)
{
return(0.0);
}
// Find camera ray after shifting a fraction of a pixel in the $y$ direction
double wty = 0.0;
foreach (double eps in new List <double> {
0.5, -0.5
})
{
CameraSample sshift = sample;
sshift.FilmPoint = new Point2D(sshift.FilmPoint.X, sshift.FilmPoint.Y + eps);
wty = GenerateRay(sshift, out Ray ry);
rd.RyOrigin = rd.Origin + (ry.Origin - rd.Origin) / eps;
rd.RyDirection = rd.Direction + (ry.Direction - rd.Direction) / eps;
if (wty != 0.0)
{
break;
}
}
if (wty == 0.0)
{
return(0.0);
}
rd.HasDifferentials = true;
return(wt);
}
public CameraSample GetCameraSample(Point2I pRaster)
{
CameraSample cs = new CameraSample(pRaster.ToPoint2D() + Get2D(), Get2D(), Get1D());
return(cs);
}
public abstract double GenerateRay(CameraSample sample, out Ray ray);
