bool IsInsidePolygon(Polyline polygon, Point3d pt)
{
int n = polygon.NumberOfVertices;
double angle = 0;
Point pt1, pt2;
for (int i = 0; i < n; i++)
{
pt1.X = polygon.GetPoint2dAt(i).X - pt.X;
pt1.Y = polygon.GetPoint2dAt(i).Y - pt.Y;
pt2.X = polygon.GetPoint2dAt((i + 1) % n).X - pt.X;
pt2.Y = polygon.GetPoint2dAt((i + 1) % n).Y - pt.Y;
angle += Angle2D(pt1.X, pt1.Y, pt2.X, pt2.Y);
}
if (Math.Abs(angle) < Math.PI)
return false;
else
return true;
}
public struct Point
{
public double X, Y;
};
public static double Angle2D(double x1, double y1, double x2, double y2)
{
double dtheta, theta1, theta2;
theta1 = Math.Atan2(y1, x1);
theta2 = Math.Atan2(y2, x2);
dtheta = theta2 - theta1;
while (dtheta > Math.PI)
dtheta -= (Math.PI * 2);
while (dtheta < -Math.PI)
dtheta += (Math.PI * 2);
return (dtheta);
}