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diff --git a/manuals/chickadee/Grids.html b/manuals/chickadee/Grids.html deleted file mode 100644 index e8ec2b6..0000000 --- a/manuals/chickadee/Grids.html +++ /dev/null @@ -1,214 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> -<html> -<!-- Copyright (C) 2017-2023 David Thompson dthompson2@worcester.edu - -Permission is granted to copy, distribute and/or modify this document -under the terms of the GNU Free Documentation License, Version 1.3 -or any later version published by the Free Software Foundation; -with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. -A copy of the license is included in the section entitled "GNU -Free Documentation License". - -A copy of the license is also available from the Free Software -Foundation Web site at http://www.gnu.org/licenses/fdl.html. - - -* Chickadee: (chickadee). Game programming toolkit for Guile. - -The document was typeset with -http://www.texinfo.org/ (GNU Texinfo). - --> -<!-- Created by GNU Texinfo 6.7, http://www.gnu.org/software/texinfo/ --> -<head> -<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> -<title>Grids (The Chickadee Game Toolkit)</title> - -<meta name="description" content="Grids (The Chickadee Game Toolkit)" /> -<meta name="keywords" content="Grids (The Chickadee Game Toolkit)" /> -<meta name="resource-type" content="document" /> -<meta name="distribution" content="global" /> -<meta name="Generator" content="makeinfo" /> -<link href="index.html" rel="start" title="Top" /> -<link href="Index.html" rel="index" title="Index" /> -<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents" /> -<link href="Data-Structures.html" rel="up" title="Data Structures" /> -<link href="Path-Finding.html" rel="next" title="Path Finding" /> -<link href="Quadtrees.html" rel="prev" title="Quadtrees" /> -<style type="text/css"> -<!-- -a.summary-letter {text-decoration: none} -blockquote.indentedblock {margin-right: 0em} -div.display {margin-left: 3.2em} -div.example {margin-left: 3.2em} -div.lisp {margin-left: 3.2em} -kbd {font-style: oblique} -pre.display {font-family: inherit} -pre.format {font-family: inherit} -pre.menu-comment {font-family: serif} -pre.menu-preformatted {font-family: serif} -span.nolinebreak {white-space: nowrap} -span.roman {font-family: initial; font-weight: normal} -span.sansserif {font-family: sans-serif; font-weight: normal} -ul.no-bullet {list-style: none} -@media (min-width: 1140px) { - body { - margin-left: 14rem; - margin-right: 4rem; - max-width: 52rem; - } -} - -@media (min-width: 800px) and (max-width: 1140px) { - body { - margin-left: 6rem; - margin-right: 4rem; - max-width: 52rem; - } -} - -@media (max-width: 800px) { - body { - margin: 1rem; - } -} - ---> -</style> -<link rel="stylesheet" type="text/css" href="https://dthompson.us/css/dthompson.css" /> - - -</head> - -<body lang="en"> -<span id="Grids"></span><div class="header"> -<p> -Next: <a href="Path-Finding.html" accesskey="n" rel="next">Path Finding</a>, Previous: <a href="Quadtrees.html" accesskey="p" rel="prev">Quadtrees</a>, Up: <a href="Data-Structures.html" accesskey="u" rel="up">Data Structures</a> [<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="Grids-1"></span><h4 class="subsection">5.6.5 Grids</h4> - -<p>The <code>(chickadee data grid)</code> module provides a simple spatial -partitioning system for axis-aligned bounding boxes -(see <a href="Rectangles.html">Rectangles</a>) in 2D space. The grid divides the world into -tiles and keeps track of which rectangles occupy which tiles. When -there are lots of moving objects in the game world that need collision -detection, the grid greatly speeds up the process. Instead of -checking collisions of each object against every other object (an -O(n^2) operation), the grid quickly narrows down which objects could -possibly be colliding and only performs collision testing against a -small set of objects. -</p> -<p>In addition to checking for collisions, the grid also handles the -resolution of collisions. Exactly how each collision is resolved is -user-defined. A player bumping into a wall may slide against it. An -enemy colliding with a projectile shot by the player may get pushed -back in the opposite direction. Two players colliding may not need -resolution at all and will just pass through each other. The way this -works is that each time an object (A) is moved within the grid, the -grid looks for an object (B) that may possibly be colliding with A. A -user-defined procedure known as a “filter” is then called with both -A and B. If the filter returns <code>#f</code>, it means that even if A and -B are colliding, no collision resolution is needed. In this case the -grid won’t waste time checking if they really do collide because it -doesn’t matter. If A and B are collidable, then the filter returns a -procedure that implements the resolution technique. The grid will -then perform a collision test. If A and B are colliding, the resolver -procedure is called. It’s the resolvers job to adjust the objects -such that they are no longer colliding. The grid module comes with a -very simple resolution procedure, <code>slide</code>, that adjusts object A -by the smallest amount so that it no longer overlaps with B. By using -this filtering technique, a game can resolve collisions between -different objects in different ways. -</p> -<dl> -<dt id="index-make_002dgrid">Procedure: <strong>make-grid</strong> <em>[cell-size 64]</em></dt> -<dd><p>Return a new grid partitioned into <var>cell-size</var> tiles. -</p></dd></dl> - -<dl> -<dt id="index-grid_003f">Procedure: <strong>grid?</strong> <em>obj</em></dt> -<dd><p>Return <code>#t</code> if <var>obj</var> is a grid. -</p></dd></dl> - -<dl> -<dt id="index-cell_003f">Procedure: <strong>cell?</strong> <em>obj</em></dt> -<dd><p>Return <code>#t</code> if <var>obj</var> is a grid cell. -</p></dd></dl> - -<dl> -<dt id="index-cell_002dcount">Procedure: <strong>cell-count</strong> <em>cell</em></dt> -<dd><p>Return the number of items in <var>cell</var>. -</p></dd></dl> - -<dl> -<dt id="index-grid_002dcell_002dsize">Procedure: <strong>grid-cell-size</strong> <em>grid</em></dt> -<dd><p>Return the cell size of <var>grid</var>. -</p></dd></dl> - -<dl> -<dt id="index-grid_002dcell_002dcount">Procedure: <strong>grid-cell-count</strong> <em>grid</em></dt> -<dd><p>Return the number of cells currently in <var>grid</var>. -</p></dd></dl> - -<dl> -<dt id="index-grid_002ditem_002dcount">Procedure: <strong>grid-item-count</strong> <em>grid</em></dt> -<dd><p>Return the number of items in <var>grid</var>. -</p></dd></dl> - -<dl> -<dt id="index-grid_002dadd">Procedure: <strong>grid-add</strong> <em>grid item x y width height</em></dt> -<dd> -<p>Add <var>item</var> to <var>grid</var> represented by the axis-aligned bounding -box whose lower-left corner is at (<var>x</var>, <var>y</var>) and is -<var>width</var> x <var>height</var> in size. -</p></dd></dl> - -<dl> -<dt id="index-grid_002dremove">Procedure: <strong>grid-remove</strong> <em>grid item</em></dt> -<dd><p>Return <var>item</var> from <var>grid</var>. -</p></dd></dl> - -<dl> -<dt id="index-grid_002dclear">Procedure: <strong>grid-clear</strong> <em>grid</em></dt> -<dd><p>Remove all items from <var>grid</var>. -</p></dd></dl> - -<dl> -<dt id="index-grid_002dmove">Procedure: <strong>grid-move</strong> <em>grid item position filter</em></dt> -<dd><p>Attempt to move <var>item</var> in <var>grid</var> to <var>position</var> (a 2D -vector) and check for collisions. For each collision, <var>filter</var> -will be called with two arguments: <var>item</var> and the item it collided -with. If a collision occurs, <var>position</var> may be modified to -resolve the colliding objects. -</p></dd></dl> - -<dl> -<dt id="index-for_002deach_002dcell">Procedure: <strong>for-each-cell</strong> <em>proc grid [rect]</em></dt> -<dd><p>Call <var>proc</var> with each cell in <var>grid</var> that intersects -<var>rect</var>, or every cell if <var>rect</var> is <code>#f</code>. -</p></dd></dl> - -<dl> -<dt id="index-for_002deach_002ditem">Procedure: <strong>for-each-item</strong> <em>proc grid</em></dt> -<dd><p>Call <var>proc</var> for each item in <var>grid</var>. -</p></dd></dl> - -<dl> -<dt id="index-slide">Procedure: <strong>slide</strong> <em>item item-rect other other-rect goal</em></dt> -<dd> -<p>Resolve the collision that occurs between <var>item</var> and <var>other</var> -when moving <var>item-rect</var> to <var>goal</var> by sliding <var>item-rect</var> -the minimum amount needed to make it no longer overlap -<var>other-rect</var>. -</p></dd></dl> - -<hr /> -<div class="header"> -<p> -Next: <a href="Path-Finding.html" accesskey="n" rel="next">Path Finding</a>, Previous: <a href="Quadtrees.html" accesskey="p" rel="prev">Quadtrees</a>, Up: <a href="Data-Structures.html" accesskey="u" rel="up">Data Structures</a> [<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> |