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1. Flying Chicken in WeScheme

   1. Change the UFO to a chicken:

   

2. 2. Change to "chicken.png"

   

   2b. Change (define UFO .... to (define CHICKEN ...

   

3. Rotate the CHICKEN.

   

   3b Type in the new code that will rotate the chicken:

   

4. Use rotate to make an upside down chicken:

   

5. Make a UFO and Chicken flying together, use (overlay/xy ...

   

   5b. Use (overlay/xy ... Here the "100 0" means over 100 and down 0 for the 2nd image

   

6. Try rotating the UFO and chicken at the same time

   

   6b. Here's the new code to type:

   

7. Make the chicken and UFO fly up instead of down:

   

8. Now make them fly diagonally:

   

9. Here's how to slow them down (or speed them up).

   

   If you would like to copy and paste the starting source code, here it is:

   (define (descend w) (+ w 5))
   
   (define (hits-floor? w) (> w 300))
   
   (define UFO 
       (image-url "http://world.cs.brown.edu/1/clipart/ufo.png"))
   
   (define (draw w)
     (place-image UFO 150 w
                  (empty-scene 300 300)))
   
   ;; The use of big-bang starts the world program.
   (big-bang 0                               ;; initially, let the height be zero.
             (on-tick descend 1/15)    ;; tick every 15 frames a second
             (on-redraw draw)              ;; use render to draw the scene
             (stop-when hits-floor?))  
   

   More pictures to try from Brown U.