private double CalcAngleForPoint(int i)
{
Line2D l1 = new Line2D(GetPoint(i - 1), GetPoint(i));
Line2D l2 = new Line2D(GetPoint(i), GetPoint(i + 1));
double a = l1.Angle(l2);
if (a < 0.0f)
{
a += (Math.PI * 2.0);
}
return(a);
}