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' This example uses the POINT function to find the border of the ellipse by
' testing for a change in color while redrawing an ellipse drawn with the
' CIRCLE statement.
 
' To try this example:
' 1. Choose New Project from the File menu
' 2. Copy the code example below to the code window
' 3. Press F5 to run the example
 
 DEFINT X-Y
 CLS                                 ' Clear the screen
 INPUT "Enter angle of tilt in degrees (0 to 90): ", Ang
 SCREEN 1                            ' Medium resolution screen
 Ang = (3.1415926# / 180) * Ang      ' Convert degrees to radians
 Cs = COS(Ang): Sn = SIN(Ang)
 CIRCLE (45, 70), 50, 2, , , 2       ' Draw ellipse
 PAINT (45, 70), 2                   ' Paint interior of ellipse
 FOR y = 20 TO 120
     FOR x = 20 TO 70
          IF POINT(x, y) <> 0 THEN   ' Check each point in rectangle
          ' enclosing ellipse; if the point is in the ellipse, plot a
          ' corresponding point in the "tilted" ellipse
          Xnew = (x * Cs - y * Sn) + 200: Ynew = (x * Sn + y * Cs)
          PSET (Xnew, Ynew), 2
          END IF
     NEXT
 NEXT
 END