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| author | David Thompson <dthompson@vistahigherlearning.com> | 2019-06-04 20:49:16 -0400 |
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| committer | David Thompson <dthompson@vistahigherlearning.com> | 2019-06-04 20:49:16 -0400 |
| commit | 279f17ac0e1b3d019c2b294098e834d249376686 (patch) | |
| tree | 47be849d3b35635d167e00cd8448815a75167a23 /manuals/chickadee/Particles.html | |
| parent | 7b808b9268ec735a7a176d10bf1887b3fa66d13e (diff) | |
Update chickadee manual.
Diffstat (limited to 'manuals/chickadee/Particles.html')
| -rw-r--r-- | manuals/chickadee/Particles.html | 263 |
1 files changed, 263 insertions, 0 deletions
diff --git a/manuals/chickadee/Particles.html b/manuals/chickadee/Particles.html new file mode 100644 index 0000000..35a6b61 --- /dev/null +++ b/manuals/chickadee/Particles.html @@ -0,0 +1,263 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 2017, 2018, 2019 David Thompson davet@gnu.org + +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 6.5, http://www.gnu.org/software/texinfo/ --> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<title>Particles (The Chickadee Game Toolkit)</title> + +<meta name="description" content="Particles (The Chickadee Game Toolkit)"> +<meta name="keywords" content="Particles (The Chickadee Game Toolkit)"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Index.html#Index" rel="index" title="Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Graphics.html#Graphics" rel="up" title="Graphics"> +<link href="Blending.html#Blending" rel="next" title="Blending"> +<link href="Fonts.html#Fonts" rel="prev" title="Fonts"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.indentedblock {margin-right: 0em} +blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smalllisp {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} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +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"> +<a name="Particles"></a> +<div class="header"> +<p> +Next: <a href="Blending.html#Blending" accesskey="n" rel="next">Blending</a>, Previous: <a href="Fonts.html#Fonts" accesskey="p" rel="prev">Fonts</a>, Up: <a href="Graphics.html#Graphics" accesskey="u" rel="up">Graphics</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Particles-1"></a> +<h4 class="subsection">2.3.6 Particles</h4> + +<p>Effects like smoke, fire, sparks, etc. are often achieved by animating +lots of little, short-lived sprites known as “particles”. In fact, +all of these effects, and more, can be accomplished by turning a few +configuration knobs in a “particle system”. A particle system takes +care of managing the many miniscule moving morsels so the developer +can quickly produce an effect and move on with their life. The +<code>(chickadee render particles)</code> module provides an API for +manipulating particle systems. +</p> +<p>Below is an example of a very simple particle system that utilizes +nearly all of the default configuration settings: +</p> +<div class="example"> +<pre class="example">(use-modules (chickadee render particles)) +(define texture (load-image "particle.png")) +(define particles (make-particles 2000 #:texture texture)) +</pre></div> + +<p>In order to put particles into a particle system, a particle +“emitter” is needed. Emitters know where to spawn new particles, +how many of them to spawn, and for how long they should do it. +</p> +<p>Below is an example of an emitter that spawns 16 particles per frame +at the coordinates <code>(320, 240)</code>: +</p> +<div class="example"> +<pre class="example">(use-modules (chickadee math vector)) +(define emitter (make-particle-emitter (vec2 320.0 240.0) 16)) +(add-particle-emitter particles emitter) +</pre></div> + +<p>To see all of the tweakable knobs and switches, read on! +</p> +<dl> +<dt><a name="index-make_002dparticles"></a>Procedure: <strong>make-particles</strong> <em>capacity [#:blend-mode <code>alpha</code>] [#:color white] [#:end-color transparent] [#:texture] [#:animation-rows 1] [#:animation-columns 1] [#:width] [#:height] [#:speed-range (vec2 0.1 1.0)] [#:acceleration-range (vec2 0.0 0.1)] [#:direction-range (vec2 0 (* 2 pi))] [#:lifetime 30] [#:sort]</em></dt> +<dd> +<p>Return a new particle system that may contain up to <var>capacity</var> +particles. Achieving the desired particle effect involves tweaking +the following keyword arguments as needed: +</p> +<p>- <var>blend-mode</var>: Pixel blending mode. <code>alpha</code> by default. +(see <a href="Blending.html#Blending">Blending</a> for more about blend modes). +</p> +<p>- <var>start-color</var>: The tint color of the particle at the beginning of its +life. White by default. +</p> +<p>- <var>end-color</var>: The tint color of the particle at the end of of its +life. Completely transparent by default for a fade-out effect. The +color in the middle of a particle’s life will be an interpolation of +<var>start-color</var> and <var>end-color</var>. +</p> +<p>- <var>texture</var>: The texture applied to the particles. The texture +may be subdivided into many animation frames. +</p> +<p>- <var>animation-rows</var>: How many animation frame rows there are in the +texture. Default is 1. +</p> +<p>- <var>animation-columns</var>: How many animation frame columns there are +in the texture. Default is 1. +</p> +<p>- <var>width</var>: The width of each particle. By default, the width of +an animation frame (in pixels) is used. +</p> +<p>- <var>height</var>: The height of each particle. By default, the height +of an animation frame (in pixels) is used. +</p> +<p>- <var>speed-range</var>: A 2D vector containing the min and max particle +speed. Each particle will have a speed chosen at random from this +range. By default, speed ranges from 0.1 to 1.0. +</p> +<p>- <var>acceleration-range</var>: A 2D vector containing the min and max +particle acceleration. Each particle will have an acceleration chosen +at random from this range. By default, acceleration ranges from 0.0 +to 0.1. +</p> +<p>- <var>direction-range</var>: A 2D vector containing the min and max +particle direction as an angle in radians. Each particle will have a +direction chosen at random from this range. By default, the range +covers all possible angles. +</p> +<p>- <var>lifetime</var>: How long each particle lives, measured in +updates. 30 by default. +</p> +<p>- <var>sort</var>: <code>youngest</code> if youngest particle should be drawn +last or <code>oldest</code> for the reverse. By default, no sorting is +applied at all. +</p></dd></dl> + +<dl> +<dt><a name="index-particles_003f"></a>Procedure: <strong>particles?</strong> <em>obj</em></dt> +<dd><p>Return <code>#t</code> if <var>obj</var> is a particle system. +</p></dd></dl> + +<dl> +<dt><a name="index-update_002dparticles"></a>Procedure: <strong>update-particles</strong> <em>particles</em></dt> +<dd><p>Advance the simulation of <var>particles</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-draw_002dparticles"></a>Procedure: <strong>draw-particles</strong> <em>particles</em></dt> +<dd><p>Render <var>particles</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-draw_002dparticles_002a"></a>Procedure: <strong>draw-particles*</strong> <em>particles matrix</em></dt> +<dd><p>Render <var>particles</var> with <var>matrix</var> applied. +</p></dd></dl> + +<dl> +<dt><a name="index-make_002dparticle_002demitter"></a>Procedure: <strong>make-particle-emitter</strong> <em>spawn-area rate [duration]</em></dt> +<dd> +<p>Return a new particle emitter that spawns <var>rate</var> particles per +frame within <var>spawn-area</var> (a rectangle or 2D vector) for +<var>duration</var> frames. If <var>duration</var> is not specified, the +emitter will spawn particles indefinitely. +</p></dd></dl> + +<dl> +<dt><a name="index-particle_002demitter_003f"></a>Procedure: <strong>particle-emitter?</strong> <em>obj</em></dt> +<dd><p>Return <code>#t</code> if <var>obj</var> is a particle emitter. +</p></dd></dl> + +<dl> +<dt><a name="index-particle_002demitter_002dspawn_002darea"></a>Procedure: <strong>particle-emitter-spawn-area</strong> <em>emitter</em></dt> +<dd><p>Return the spawn area for <var>emitter</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-particle_002demitter_002drate"></a>Procedure: <strong>particle-emitter-rate</strong> <em>emitter</em></dt> +<dd><p>Return the number of particles that <var>emitter</var> will spawn per +frame. +</p></dd></dl> + +<dl> +<dt><a name="index-particle_002demitter_002dlife"></a>Procedure: <strong>particle-emitter-life</strong> <em>emitter</em></dt> +<dd><p>Return the number of frames remaining in <var>emitter</var>’s lifespan. +</p></dd></dl> + +<dl> +<dt><a name="index-particle_002demitter_002ddone_003f"></a>Procedure: <strong>particle-emitter-done?</strong> <em>emitter</em></dt> +<dd><p>Return <code>#t</code> if <var>emitter</var> has finished spawning particlces. +</p></dd></dl> + +<dl> +<dt><a name="index-add_002dparticle_002demitter"></a>Procedure: <strong>add-particle-emitter</strong> <em>particles emitter</em></dt> +<dd><p>Add <var>emitter</var> to <var>particles</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-remove_002dparticle_002demitter"></a>Procedure: <strong>remove-particle-emitter</strong> <em>particles emitter</em></dt> +<dd><p>Remove <var>emitter</var> to <var>particles</var> +</p></dd></dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Blending.html#Blending" accesskey="n" rel="next">Blending</a>, Previous: <a href="Fonts.html#Fonts" accesskey="p" rel="prev">Fonts</a>, Up: <a href="Graphics.html#Graphics" accesskey="u" rel="up">Graphics</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |