Updates for Chickadee 0.8.0 and Guile-SDL2 0.7.0.

author: David Thompson <dthompson2@worcester.edu> 2021-10-07 20:17:50 -0400
committer: David Thompson <dthompson2@worcester.edu> 2021-10-07 20:17:50 -0400
commit: 0e699be281c8dea53e589e08a5831837e0eae7ea (patch)
tree: 4266aebec927b13ca56410be1901e3ee78dff49e /manuals/chickadee/Quadtrees.html
parent: 38daa330f2194de5f39cd41b270c89d7b2e94427 (diff)
1 files changed, 222 insertions, 0 deletions
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+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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+<!-- Copyright (C) 2017-2021  David Thompson davet@gnu.org
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+* Chickadee: (chickadee).     Game programming toolkit for Guile.
+
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+<title>Quadtrees (The Chickadee Game Toolkit)</title>
+
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+</head>
+
+<body lang="en">
+<span id="Quadtrees"></span><div class="header">
+<p>
+Next: <a href="Grids.html" accesskey="n" rel="next">Grids</a>, Previous: <a href="Heaps.html" accesskey="p" rel="prev">Heaps</a>, Up: <a href="Data-Structures.html" accesskey="u" rel="up">Data Structures</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html" title="Index" rel="index">Index</a>]</p>
+</div>
+<hr>
+<span id="Quadtrees-1"></span><h4 class="subsection">5.6.4 Quadtrees</h4>
+
+<p>The <code>(chickadee data quadtree)</code> module provides a 2D spatial
+partitioning implementation known as a &ldquo;quadtree&rdquo;.  A quadtree
+recursively subdivides the world into rectangular quadrants.  This
+data structure is very useful for handling broad-phase collision
+detection because it can quickly determine the objects that may
+possibly be colliding with another, resulting in fewer narrow-phase
+collision tests that are typically much more expensive.
+</p>
+<dl>
+<dt id="index-make_002dquadtree">Procedure: <strong>make-quadtree</strong> <em>bounds [#:max-size 5] [#:max-depth 4]</em></dt>
+<dd><p>Return a new quadtree that covers the area <var>bounds</var>.  Each node
+will try to hold at maximum <var>max-size</var> objects and the tree depth
+will be restricted to <var>max-depth</var>.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_003f">Procedure: <strong>quadtree?</strong> <em>obj</em></dt>
+<dd><p>Return <code>#t</code> if <var>obj</var> is a quadtree.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dclear_0021">Procedure: <strong>quadtree-clear!</strong> <em>quadtree</em></dt>
+<dd><p>Clear all objects from <var>quadtree</var>.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dinsert_0021">Procedure: <strong>quadtree-insert!</strong> <em>quadtree rect object</em></dt>
+<dd><p>Insert <var>object</var> with bounding box <var>rect</var> into <var>quadtree</var>.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002ddelete_0021">Procedure: <strong>quadtree-delete!</strong> <em>quadtree rect object</em></dt>
+<dd><p>Delete <var>object</var>, who occupies the space <var>rect</var>, from
+<var>quadtree</var>.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dfind">Procedure: <strong>quadtree-find</strong> <em>rect pred</em></dt>
+<dd><p>Return the first object in <var>quadtree</var> in the vicinity of
+<var>rect</var> that satisfies <var>pred</var>.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dfold">Procedure: <strong>quadtree-fold</strong> <em>quadtree rect init proc</em></dt>
+<dd><p>Apply <var>proc</var> to all objects in the vicinity of <var>rect</var> in
+<var>quadtree</var> to build a result and return that result.  <var>init</var>
+is the initial result.  If there are no objects in the vicinity of
+<var>rect</var>, just <var>init</var> is returned.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dfor_002deach">Procedure: <strong>quadtree-for-each</strong> <em>quadtree rect proc</em></dt>
+<dd><p>Call <var>proc</var> for all objects in the vicinity of <var>rect</var> in
+<var>quadtree</var>.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dleaf_003f">Procedure: <strong>quadtree-leaf?</strong> <em>quadtree</em></dt>
+<dd><p>Return <code>#t</code> if <var>quadtree</var> is a leaf node.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dbounds">Procedure: <strong>quadtree-bounds</strong> <em>quadtree</em></dt>
+<dd><p>Return the bounding rectangle of <var>quadtree</var>.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dmax_002ddepth">Procedure: <strong>quadtree-max-depth</strong> <em>quadtree</em></dt>
+<dd><p>Return the maximum depth of <var>quadtree</var>.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dmax_002dsize">Procedure: <strong>quadtree-max-size</strong> <em>quadtree</em></dt>
+<dd><p>Return the desired per-node maximum object count of <var>quadtree</var>.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002ddepth">Procedure: <strong>quadtree-depth</strong> <em>quadtree</em></dt>
+<dd><p>Return the depth of the node <var>quadtree</var>.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dsize">Procedure: <strong>quadtree-size</strong> <em>quadtree</em></dt>
+<dd><p>Return the number of objects stored in the node <var>quadtree</var>.
+</p></dd></dl>
+
+<p>Non-leaf nodes always have four child nodes, which correspond to the
+quadrants of a Cartesian coordinate system:
+</p>
+<pre class="verbatim">*------*------*
+|      |      |
+|  Q2  |  Q1  |
+|      |      |
+*------*------*
+|      |      |
+|  Q3  |  Q4  |
+|      |      |
+*------*------*
+</pre>
+<dl>
+<dt id="index-quadtree_002dq1">Procedure: <strong>quadtree-q1</strong> <em>quadtree</em></dt>
+<dd><p>Return the upper-right child node of <var>quadtree</var>, or <code>#f</code> if
+<var>quadtree</var> is a leaf node.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dq2">Procedure: <strong>quadtree-q2</strong> <em>quadtree</em></dt>
+<dd><p>Return the upper-left child node of <var>quadtree</var>, or <code>#f</code> if
+<var>quadtree</var> is a leaf node.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dq3">Procedure: <strong>quadtree-q3</strong> <em>quadtree</em></dt>
+<dd><p>Return the lower-left child node of <var>quadtree</var>, or <code>#f</code> if
+<var>quadtree</var> is a leaf node.
+</p></dd></dl>
+
+<dl>
+<dt id="index-quadtree_002dq4">Procedure: <strong>quadtree-q4</strong> <em>quadtree</em></dt>
+<dd><p>Return the lower-right child node of <var>quadtree</var>, or <code>#f</code> if
+<var>quadtree</var> is a leaf node.
+</p></dd></dl>
+
+<hr>
+<div class="header">
+<p>
+Next: <a href="Grids.html" accesskey="n" rel="next">Grids</a>, Previous: <a href="Heaps.html" accesskey="p" rel="prev">Heaps</a>, Up: <a href="Data-Structures.html" accesskey="u" rel="up">Data Structures</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html" title="Index" rel="index">Index</a>]</p>
+</div>
+
+
+
+</body>
+</html>
author	David Thompson <dthompson2@worcester.edu>	2021-10-07 20:17:50 -0400
committer	David Thompson <dthompson2@worcester.edu>	2021-10-07 20:17:50 -0400
commit	0e699be281c8dea53e589e08a5831837e0eae7ea (patch)
tree	4266aebec927b13ca56410be1901e3ee78dff49e /manuals/chickadee/Quadtrees.html
parent	38daa330f2194de5f39cd41b270c89d7b2e94427 (diff)