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world docs fixed

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svn: r5156
This commit is contained in:
Matthias Felleisen 2006-12-21 19:03:54 +00:00
parent 9fd71be16c
commit 981066f787
1 changed files with 38 additions and 7 deletions
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collects/teachpack/htdp/Docs/world.thtml
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@ -1,12 +1,43 @@
{ (define LIBNAME "Animated Images")
{ (define LIBNAME "Animated Images, Simulating Worlds")
(include "head.tinc") }
<p>The teachpack provides two kinds of functions. The first four allow
<p>The teachpack provides two kinds of functions. The first five allow
students to simulate a small world of animated drawings and games:
<menu>
<li><code>{(idx big-bang)} : Number Number Number World -> true</code><br>
<li><code>{(idx run-simulation)} : Nat Nat Number [Nat -> Image] -> true</code><br>
<code>(run-simulation width height r create-image)</code>
creates and shows a <code>width</code> x <code>height</code> canvas,
starts a clock, ticking every <code>r</code> (usually fractional) seconds,
and, every time the clock ticks, it applies <code>create-image</code> to
the number of ticks passed since this function call.
<p>In addition, the function pops up a frame and displays the pictures that
<code>create-image</code> generates. The result is a simple animation.
</p>
<p><b>Example:</b>
<pre>
<code>
(define (create-UFO-scene height)
(place-image UFO 50 height (empty-scene 100 100)))
(define UFO (overlay (circle 10 'solid 'green) (rectangle 40 4 'solid 'green)))
(run-simulation 100 100 (/ 1 28) create-UFO-scene)
</code>
</pre>
</p>
<p>
The <code>Stop</code> button on the frame allows users to stop the clock
and thus the simulation. It also enables the <code>Images</code> button,
which then allows users to create images of all the steps taken since the
beginning of time.
</p>
<li><code>{(idx big-bang)} : Nat Nat Number World -> true</code><br>
<code>(big-bang width height n w)</code>
creates and shows a width x height canvas,
creates and shows a <code>width</code> x <code>height</code> canvas,
starts the clock,
makes it tick every n seconds,
and makes w the first world
@ -33,7 +64,7 @@ students to simulate a small world of animated drawings and games:
or the events of releasing a key on the keypad.
</pre>
<li><code>{(idx on-mouse-event)} : (World Number Number MouseEvent ->
<li><code>{(idx on-mouse-event)} : (World Nat Nat MouseEvent ->
World) -> true</code><br> <code>(on-mouse-event clack)</code> means that
DrScheme must call <code>clack</code> on the current world, the current
<code>x</code> and <code>y</code> coordinates of the mouse, and and a
@ -69,12 +100,12 @@ students to simulate a small world of animated drawings and games:
<p>The rest are functions for creating scenes:
<menu>
<li><code>{(idx nw:rectangle)} : Number Number Mode Color -> Image</code><br>
<li><code>{(idx nw:rectangle)} : Nat Nat Mode Color -> Image</code><br>
<code>(nw:rectangle width height mode color)</code>
creates a width x height rectangle, solid or outlined,
with its anchor in the NW corner
<li><code>{(idx empty-scene)} : Number Number -> Scene</code><br>
<li><code>{(idx empty-scene)} : Nat Nat -> Scene</code><br>
<code>(empty-scene width height)</code>
creates a width x height "scene" (frame with origin in NW)