DrawPolygon - Draw a closed polygon with any number of sides

' Draw a polygon, given its center and number of sides
' CTRL can be either a form or a PictureBox control.
' ANGLE is an optional angle in degrees

Sub DrawPolygon(ctrl As Object, ByVal xc As Single, ByVal yc As Single, _
    ByVal side As Single, ByVal numSides As Integer, _
    Optional ByVal angle As Single)
    Dim deltaAngle As Single
    Dim r As Single
    Dim i As Integer
    Dim x2 As Single
    Dim y2 As Single
    
    ' evaluate the angle formed by each side (in radians)
    deltaAngle = 3.14159265358979 * 2 / numSides
    ' evaluate the radius of the circle that wraps the polygon.
    r = side / Sin(deltaAngle / 2)
    ' convert the initial angle in radians
    angle = angle / 57.2957795130824
    
    ' Draw individual sides
    For i = 1 To numSides
        ctrl.Line (xc + r * Sin(angle), yc + r * Cos(angle))-(xc + r * Sin _
            (angle + deltaAngle), yc + r * Cos(angle + deltaAngle))
        angle = angle + deltaAngle
    Next

End Sub