How to tell if a line intersects a polygon in C#?

Question

I have a question very similar to this:

How to know if a line intersects a plane in C#?

I am searching for a method (in C#) tha

Answer 1

Slightly off topic, but if the line is infinite I think there's a much simpler solution:

The line does not go through the polygon if all the point lie on the same side of the line.

With help from these two:

• Using linq or otherwise, how do check if all list items have the same value and return it, or return an “otherValue” if they don’t?
• Determine which side of a line a point lies

I got this little gem:

  public class PointsAndLines
  {
    public static bool IsOutside(Point lineP1, Point lineP2, IEnumerable region)
    {
      if (region == null || !region.Any()) return true;
      var side = GetSide(lineP1, lineP2, region.First());
      return
        side == 0
        ? false
        : region.All(x => GetSide(lineP1, lineP2, x) == side);
    }

    public static int GetSide(Point lineP1, Point lineP2, Point queryP)
    {
      return Math.Sign((lineP2.X - lineP1.X) * (queryP.Y - lineP1.Y) - (lineP2.Y - lineP1.Y) * (queryP.X - lineP1.X));
    }
  }