BallToss

From MHCGraphics

; Mead example file -- a simple animation of a ball
; tossed from one point to another
;
; Jim Teresco
; Computer Science 110
; Mount Holyoke College
;
; $Id: BallToss.scm 612 2008-04-06 01:19:20Z terescoj $
;
(require (lib "Defs.ss" "Mead"))

; Some image settings appropriate for animations
(tell image
      ; set the filename of the images
      (fileName "BallToss")
      ; frameNumbers must start at 0
      (frameNumber 0)
      ; set to #t for default behavior: view images,
      ; but here we only want to see the final movie
      (viewResult #f)
      )

; And some standard image properties
(tell image
      (background '(.5 .5 1))
      )

; get a new scene with my own light
(object sun Light
        (intensity 1)
        (translate 0 500 -500))

; and the ground
(object ground Plane
        (material greenPlaster)
        )

(object scene Group
        (add sun)
        (add ground)
        )

; The object we will be animating is a white sphere,
; which we create here and add to the scene
(object ball Sphere
        (material whitePlastic)
        ;(scale .5 .5 .5)
        )
(tell scene (add ball))

; next, we define an adjustment function that sets the 
; position of the ball for each frame of our film
(define (moveBall pos)
  (tell ball 
        ; absoluteXform forgets any previous
        ; transformations of the object.
        ; we have been using relativeXform (the default)
        (absoluteXform 
         (compose
          (scale .33 .33 .33)
          (translate (car pos)(cadr pos)(caddr pos))
          )
         )
        )
  )

; tell the camera to film!
(tell camera
      (pos '(0 100 -600))
      (coi '(0 50 0))
      ; we send a film message which uses morph to create
      ; a series of values to pass to the given function.
      ; The parameters to morph are the lists of values
      ; given after the function name.
      ; In this case, there is just a single list, so
      ; moveBall has one parameter -- one set the coordinates
      ; returned by (morph 50 ...) on the parameters given.
      (film 50 moveBall 
            '((-200 50 0) (-100 300 0) (100 300 0) (200 50 0)))
      ; now tell the camera to take the frames it just filmed
      ; and paste them together into a movie
      (buildMovie)
      )