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rewrote world.ss; it had gotten out of sync with code

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svn: r7523
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Matthias Felleisen 2007-10-18 14:36:24 +00:00
parent e20126af45
commit 012895cbfe
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collects/teachpack/htdp/Docs/world.thtml
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@ -1,10 +1,12 @@
{ (define LIBNAME "Animated Images, Simulating Worlds")
(include "head.tinc") }
<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 run-simulation)} : Nat Nat Number [Nat -> Scene] -> true</code><br>
<p>The teachpack provides the tools to write simple animations and
interactive games. The first and simplest approach is to set up a
simulation:
<blockquote>
<code>{(idx run-simulation)} : Nat Nat Number [Nat -> Scene] -> 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,
@ -12,14 +14,13 @@ students to simulate a small world of animated drawings and games:
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>
<code>create-image</code> generates. The result is a simple animation.</p>
<p>Optional: the function consumes an optional fifth argument, a
boolean. If this argument is <code>false</code> or missing,
<code>run-simulation</code> acts as described; if it is present and
<code>true</code>, the function can create an animated GIF of the
simulation after you stop it.</p>
boolean. If this argument is <code>false</code> or missing,
<code>run-simulation</code> acts as described; if it is present and
<code>true</code>, the function can create an animated GIF of the
simulation after you stop it.</p>
<p><b>Example:</b>
<pre>
@ -33,20 +34,26 @@ simulation after you stop it.</p>
</code>
</pre>
</p>
</blockquote>
<p>The teachpack assumes two basic kinds of data:
<p>For animated worlds and games, using the teachpack requires that you
provide a data definition for <code>World</code>. In principle, there are
no constraints on this data definition. </p>
<p>The teachpack works with two basic forms of data for visualizing the world:
<ul>
<li><code>World</code>, which is something you must define;
</li>
<li><code>Image</code>, which are either inserted into DrScheme via the
"Special" menu or constructed from the functions below; and
</li>
<li><code>Scene</code>, which are created from <code>Image</code>s. Indeed,
they are just special images.
</li>
"Special" menu or constructed from the functions below; and </li>
<li><code>Scene</code>, which are created from <code>Image</code>s.
Specifically, a scene is an image whose pinhole is at position (0,0).</li>
</ul>
</p>
Given a data definition for worlds, the following functions create worlds,
visualize it, make the clock tick, and provide feedback about the mouse and
keyboard actions that the program's users perform:
<ol>
<li><code>{(idx big-bang)} : Nat Nat Number World -> true</code><br>
<code>(big-bang width height n w)</code>
creates and shows a <code>width</code> x <code>height</code> canvas,
@ -113,10 +120,13 @@ simulation after you stop it.</p>
<li><code>{(idx end-of-time)} : String u Symbol -> World</code><br> When DrScheme
evaluates <code>(end-of-time "the end")</code>, it stops the clock and displays the
given string or symbol; no further tick events, key events, or redraw events
take place until the world is created again. </menu></p>
take place until the world is created again.
</ol></p>
<p>The rest are functions for creating scenes:
<menu>
<p>For the creation of scenes from the world, use the following functions
plus the functions on images below:
<ol>
<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,
@ -143,7 +153,7 @@ simulation after you stop it.</p>
<code>(run-movie loi)</code>
shows the list of images in loi in a time-delayed manner;
assume: all images are of the same size
</menu></p>
</ol></p>
<hr />