Doughnuts

From MHCGraphics

; Mead example file -- A line of doughnuts
;
; Jim Teresco
; Computer Science 110
; Mount Holyoke College
;
; $Id: Doughnuts.scm 594 2008-03-31 01:06:20Z terescoj $
;
(require (lib "Defs.ss" "Mead"))

; Some size parameters for our doughnuts
(define doughnutThickness 30)
(define doughnutSize 90)

; First, we create a doughnut object
; We can do this with a Mead Torus object
; For a Torus, we specify the major radius and minor radius.
; The minor radius determines the thickness of the cross
; section, the major radius how big a circle is traced out
; with the cross section.
; In this case, it means our doughnuts occupy a space
; that is 90x30x90, centered above the origin
(object doughnut Torus
        (major (/ (- doughnutSize doughnutThickness) 2))
        (minor (/ doughnutThickness 2))
        (material yellowPlaster)
        (translate 0 (/ doughnutThickness 2) 0)
        )

; We'll put a bunch of doughnuts in a line, lined
; up sitting on the xz-plane atop the x-axis.
; To do this, we write a function:

; This function adds multiple objects to a group (often 
; the scene).  The "initialXform" is a transformation that
; is applied to the "prototype" object, obj,
; to place the first instance in the scene.
; The "deltaXform" takes us from one to the next.

(define (multiAdd n obj group initialXform deltaXform)
  (if (<= n 0) group ; return the group, if nothing to be added
      (begin  ; if something, add one, then the rest
        (tell group
              (add obj initialXform)
              )
        (multiAdd (- n 1) obj group
                  (compose initialXform deltaXform)
                  deltaXform)
        )
      )
  )

(define numDoughnuts 12)
(define doughnutSpacing (* 1.1 doughnutSize))

(multiAdd numDoughnuts doughnut scene
          (translate (- (* (/ numDoughnuts 2) doughnutSpacing))
                     0 0)
          (translate doughnutSpacing 0 0))

(tell image
      (background white))

(tell camera
      (pos '(0 300 -500))
      (shoot))