/// <summary>
/// Minimal degree between vectors
/// </summary>
public static float Angle(this PointF c1, PointF c2)
{
var a = c1.Angle() - c2.Angle();
a += (float)((a > PI) ? -2 * PI : (a < -PI) ? 2 * PI : 0);
return(a);
}
public static float Subtend(this PointF point, PointF a1, PointF a2)
{
a1 = a1.Subtract(point);
a2 = a2.Subtract(point);
float angleA = a1.Angle(), angleB = a2.Angle();
if (angleA > angleB)
{
float swap = angleA;
angleA = angleB;
angleB = swap;
}
return (float)((angleB - angleA + (Math.PI * 2)) % (Math.PI * 2));
}