''' <summary>Schnittpunkt zweier Geraden</summary>
''' <param name="p1">erster Punkt auf Gerade 1</param>
''' <param name="e1">zweiter Punkt aus Gerade 1</param>
''' <param name="p2">erster Punkt auf Gerade 2</param>
''' <param name="e2">zweiter Punkt auf Gerade 2</param>
''' <returns>Schnittpunkt (oder Nothing)</returns>
Public Function Schnittpunkt(p1 As Point, e1 As Point, _
                             p2 As Point, e2 As Point) As Point
 
   Dim x1, x2, x3, x4, y1, y2, y3, y4 As Integer
 
   x1 = p1.X : x2 = e1.X : y1 = p1.Y : y2 = e1.Y
   x3 = p2.X : x4 = e2.X : y3 = p2.Y : y4 = e2.Y
 
   Dim nenner As Double = (y4 - y3) * (x2 - x1) - (y2 - y1) * (x4 - x3)
   If Math.Abs(nenner) < 0.00001 Then Return Nothing
 
   Dim xs_zähler As Double = _
      (x4 - x3) * (x2 * y1 - x1 * y2) - (x2 - x1) * (x4 * y3 - x3 * y4)
   Dim ys_zähler As Double = _
      (y1 - y2) * (x4 * y3 - x3 * y4) - (y3 - y4) * (x2 * y1 - x1 * y2)
 
   Return New Point(CInt(xs_zähler / nenner), CInt(ys_zähler / nenner))
 
End Function