public static Vector3D Normal(
this IParametricSurface surface,
Parametrisation parametrisation)
{
var du = surface.Derivative(
parametrisation,
DerivativeParameter.U
);
var dv = surface.Derivative(
parametrisation,
DerivativeParameter.V
);
return(Vector3D.CrossProduct(du, dv));
}
public static Vector3D Derivative(
this IParametricSurface surface,
Parametrisation parametrisation,
DerivativeParameter parameter
)
{
return(surface.Derivative(
parametrisation.U,
parametrisation.V,
parameter
));
}
public void DrawDerivative(
IParametricSurface surface,
double u,
double v,
DerivativeParameter parameter,
Color?color = null
)
{
var point = surface.Evaluate(u, v);
var derivative = surface.Derivative(u, v, parameter);
DrawVector(point, derivative, derivative.Length, color);
}