public Vector3D Derivative(
double u, double v,
DerivativeParameter parameter
)
{
double firstParameter, secondParameter;
Func <int, Point3D[]> generator;
switch (parameter)
{
case DerivativeParameter.U:
generator = (i) => ArrayHelpers.GetColumn(ControlPoints, i);
firstParameter = v;
secondParameter = u;
break;
case DerivativeParameter.V:
generator = (i) => ArrayHelpers.GetRow(ControlPoints, i);
firstParameter = u;
secondParameter = v;
break;
default:
throw new ArgumentOutOfRangeException(
nameof(parameter),
parameter,
null
);
}
var subpoints = new List <Point3D>();
for (var i = 0; i < 4; ++i)
{
subpoints.Add(BernsteinPolynomial.Evaluate3DPolynomial(
generator(i),
firstParameter
));
}
var derivative = BernsteinPolynomial.CalculateDerivative(subpoints);
return((Vector3D)BernsteinPolynomial.Evaluate3DPolynomial(
derivative,
secondParameter
));
}