Point in Poly?

Below is my implementation of the Winding Number method. I ripped this out of my SA_GameMod libraries, so it used to be a method of my one of my GameMod types and it requires a simple struct-style "Point" which I will also post below.

  ' Function arguments: 
  ' _x = Mouse X position
  ' _y = Mouse Y position
  ' Points = An array of SA_GameObject_Point objects
  ' Returns:
  ' 0 if point _x, _y is outside polygon
  ' 1 if point _x, _y is inside polygon
  Function IsIn%(_x#, _y#, Points:SA_GameObject_Point[])
    Local xs% = 0

    For Local i% = 0 To Points.Length-2
    	If (( (Points[i].y <= _y) And (Points[i+1].y > _y) ) Or ( (Points[i].y > _y) And (Points[i+1].y <= _y) ))
    		Local sect# = Float((_y - Points[i].y) / (Points[i+1].y - Points[i].y))
    		If (_x < Points[i].x + sect*(Points[i+1].x - Points[i].x)) xs :+ 1
    	End If
    Next
    Return xs&1
  End Method

The Point type:

' ========================================
' SA_GameObject_Point - A "point" on the
' drawing surface or board defined by X, Y.
' Mainly used to define polygons.
' ========================================

Type SA_GameObject_Point
	Field x#, y#
	
       ' Creates and returns an SA_GameObject_Point
       ' of _x, _y
	Function Create:SA_GameObject_Point(_x#, _y#)
	  Local p:SA_GameObject_Point = new SA_GameObject_Point
		p.x = _x
		p.y = _y
		Return p
	End Function
End Type

Like I said, I ripped this from my SA_GameMod files and made a few quick edits to make it stand-alone but I haven't tested it as stand-alone. It works perfectly in my game mod, though.

SpaceAce