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scene fixed in world

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svn: r10863
This commit is contained in:
Matthias Felleisen 2008-07-22 21:00:07 +00:00
parent 2e7047b87f
commit e50f229beb
1 changed files with 6 additions and 3 deletions
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9
collects/teachpack/htdp/scribblings/world.scrbl
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@ -21,9 +21,12 @@ The teachpack assumes working knowledge of the basic image manipulation
primitives and introduces a special kind of image: a scene.
@deftech{Scene}@;
@schemeblock[(and/c image?
(lambda (i)
(and (= (pinhole-x i) 0) (= (pinhole-y i) 0))))]
@schemeblock[
;; Image -> Boolean
(define (focus-at-0-0 i)
(and (= (pinhole-x i) 0) (= (pinhole-y i) 0)))
(and/c image? focus-at-0-0)]
The teachpack can display only @tech{Scene}s, which are images whose
pinholes are at position @scheme[(0,0)].