public ICurve Convert()
{
if (P3.LengthSquared() > 0)
{
return(new CubicCurve(P0, P1, P2, P3));
}
if (P2.LengthSquared() > 0)
{
return(new QuadraticCurve(P0, P1, P2));
}
return(new LinearCurve(P0, P1));
}