public DifferentialGeometry(Point P, Vector DPDU, Vector DPDV, Normal DNDU, Normal DNDV, double uu, double vv, Shape sh)
{
p = P; dpdu = DPDU; dpdv = DPDV; dndu = DNDU; dndv = DNDV;
// Initialize _DifferentialGeometry_ from parameters
nn = new Normal(Geometry.Normalize(Geometry.Cross(dpdu, dpdv)));
u = uu;
v = vv;
shape = sh;
dudx = dvdx = dudy = dvdy = 0.0d;
// Adjust normal based on orientation and handedness
if (shape != null && (shape.ReverseOrientation ^ shape.TransformSwapsHandedness)) nn *= -1.0d;
}
public GeometricPrimitive(Shape s, Material m, AreaLight a)
{
shape = s;
material = m;
areaLight = a;
}