I think I found the solution.
I still have to design the render function.
I have this :
; niet grafische constanten.
(define lengte-werkblad 200)
(define breedte-werkblad 1000)
(define move-animal 3)
(define move-gauge 0.1)
; grafische constanten
(define kat .)
(define cham .)
(define workspace (empty-scene breedte-werkblad lengte-werkblad))
(define gauge-omtrek (rectangle 1000 20 "outline" "black"))
; berekende constanten
(define correctie-cat ( / (image-width kat)2))
(define ondergrens-cat ( - 0 correctie-cat))
(define bovengrens-cat ( + breedte-werkblad correctie-cat))
(define correctie-cham ( / (image-width cham)2))
(define ondergrens-cham ( - 0 correctie-cham))
(define bovengrens-cham ( + breedte-werkblad correctie-cham))
; Te gebruiken structs
; Design a world program that works with both cats and chameleons:
; A VAnimal is either
; -- a VCat
; -- a VCham
(define-struct Vcat (Xcat Hcat Richting))
; Vcat = (make-editor Number Number)
; interp. (make-editor x h r) where x is the x-coordinate of the cat and
h is the happiness of the cat and r the way the cat walks.
; make-editor Number Number String -> Vcat
; Vcat-Xcat Editor -> Number
; Vcat-Hcat Editor -> Number
; Vcat-Richting -> String
; Vcat? Editor Any -> Boolean
(define-struct Vcham (Xcham Hcham Richting))
; Vcham = (make-editor Number Number)
; interp. (make-editor x h r) where x is the x-coordinate of the cham
and h is the happiness of the cham and r the way the cham walks.
; make-editor Number Number String -> Vcat
; Vcham-Xcham Editor -> Number
; Vcham-Hcham Editor -> Number
; Vcham-Richting -> String
; Vcham? Editor Any -> Boolean
; Vcham -> Vcham
; Function who makes the image move to the left or turn to the right
(check-expect (links-of-draaien-cham (make-Vcham 20 100 "left"))
(make-Vcham 17 99.9 "left"))
(check-expect (links-of-draaien-cham (make-Vcham -39 100 "left"))
(make-Vcham -39 99.9 "right"))
(check-expect (links-of-draaien-cham (make-Vcham 1037 100 "left"))
(make-Vcham 1034 99.9 "left"))
(define (links-of-draaien-cham s)
(if ( < (Vcham-Xcham Vcham) ondergrens-cham)
(make-Vcham (Vcham-Xcham s) (- (Vcham-Hcham s) move-gauge) "right")
(make-Vcham (- (Vcham-Xcham s) move-animal) (- (Vcham-Hcham s)
move-gauge) "left")))
; Vcat -> Vcat
; Function who makes the image move to the left or turn to the right
(check-expect (links-of-draaien-cat (make-Vcat 20 100 "left"))
(make-Vcat 17 99.9 "left"))
(check-expect (links-of-draaien-cat (make-Vcat -39 100 "left"))
(make-Vcat -39 99.9 "right"))
(check-expect (links-of-draaien-cat (make-Vcat 1037 100 "left"))
(make-Vcat 1034 99.9 "left"))
(define (links-of-draaien-cat s)
(if ( < (Vcat-Xcat Vcat) ondergrens-cat)
(make-Vcat (Vcat-Xcat s) (- (Vcat-Hcat s) move-gauge) "right")
(make-Vcat (- (Vcat-Xcat s) move-animal) (- (Vcat-Hcat s)
move-gauge) "left"))
)
; Vcham -> Vcham
; Function who makes the image move to the right or turn to the left
(check-expect (rechts-of-draaien-cham (make-Vcham 20 100 "right"))
(make-Vcham 23 99.9 "right"))
(check-expect (rechts-of-draaien-cham (make-Vcham -39 100 "right"))
(make-Vcham -36 99.9 "right"))
(check-expect (rechts-of-draaien-cham (make-Vcham 1040 100 "right"))
(make-Vcham 1040 99.9 "left"))
(define (rechts-of-draaien-cham s)
(if ( > (Vcham-Xcham Vcham) bovengrens-cham)
(make-Vcham (Vcham-Xcham s) (- (Vcham-Hcham s) move-gauge) "left")
(make-Vcham (+ (Vcham-Xcham s) move-animal) (- (Vcham-Hcham s)
move-gauge) "right")))
; Vcat -> Vcat
; Function who makes the image move to the right or turn to the left
(check-expect (rechts-of-draaien-cat (make-Vcat 20 100 "right"))
(make-Vcat 23 99.9 "right"))
(check-expect (rechts-of-draaien-cat (make-Vcat -39 100 "right"))
(make-Vcat -36 99.9 "right"))
(check-expect (rechts-of-draaien-cat (make-Vcat 1040 100 "right"))
(make-Vcat 1040 99.9 "left"))
(define (rechts-of-draaien-cat s)
(if ( > (Vcat-Xcat Vcat) bovengrens-cat)
(make-Vcat (Vcat-Xcat s) (- (Vcat-Hcat s) move-gauge) "left")
(make-Vcat (+ (Vcat-Xcat s) move-animal) (- (Vcat-Hcat s)
move-gauge) "right"))
)
; Vanimal -> Vanimal
; Function which change the world on clock ticks.
; On every tick the X-coordinate changes 3 pixels and the happiness
decrease with 0.1.
(define (tock s)
(cond
[(Vcat? s)(if(equal? (Vcat-Richting s) "left")
(links-of-draaien-cat Vcat) (rechts-of-draaien-cat Vcat))]
[(Vcham? s) (if(equal? (Vcham-Richting s) "left")
(links-of-draaien-cham Vcham) (rechts-of-draaien-cat Vcham))]
))
(define (render s)s)
(define (main s)
(cond
[(Vcat? s) (big-bang s (check-with Vcat?) (on-tick tock) (on-draw
render) )]
[(Vcham? s) (big-bang s (check-with Vcham?) (on-tick tock) (on-draw
render) )]
))
(main (make-Vcat 12 100 "left"))
Is this better ?
Roelof
Op 30-6-2012 9:03, Roelof Wobben schreef:
Op 30-6-2012 1:38, Neil Van Dyke schreef:
Stephen Bloch wrote at 06/29/2012 06:01 PM:
Either you introduce this stuff much better than I do, or your
students are much sharper.
For the possible benefit of any students reading, I think someone say
it, rather than leave it implied: Or the difference could be an
isolated effect of, say, some subtle difference in how one concept
was first introduced in their respective educations, not a reflection
on the instruction or students overall.
Aside: I think students are much the same everywhere, and most all
students have potential to be good at this stuff. But learning this
stuff well requires a lot of work, and I think students generally do
need to have sufficient sense that they're ``sharp,'' so that they
stick with it and put in the necessary work. Or, there is another
category of person, who sees themself as slow but determined; that
will also lead to learning the stuff, if the self image gets them to
put in the necessary work. (However, the ones who are self-assured
and yet who don't do the learning work... they are doomed to be dim
and to have few job options other than some kind of politician.)
Neil V.
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Im rereading the chapter and I think I found a piece of the puzzle.
In the chapter there is a mention of this :
;A SIGS(short for "space invader game state") is one of:
;--(make-aimUFO <#%28tech._mix._ufo%29>Tank <#%28tech._mix._tank%29>)
;--(make-firedUFO <#%28tech._mix._ufo%29>Tank
<#%28tech._mix._tank%29>Missile <#%28tech._mix._missile%29>)
I can do the same for my problem.
; A Vanimal is one of :
; - (make-Vcat ( x happiness)
; (make-Vcham ( x happiness)
So Vanimal is not a struct but strictly a name.
Am I on the right track.
Roelof
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