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| author | David Thompson <dthompson2@worcester.edu> | 2023-12-28 11:23:49 -0500 |
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| committer | David Thompson <dthompson2@worcester.edu> | 2023-12-28 11:23:49 -0500 |
| commit | 25c5eac5e6ca1035db1eddd7bea9ac78531da57e (patch) | |
| tree | 96377006bbfee75bcf0ce208c1ef89cbdfa5b803 /manuals/chickadee/Shaders.html | |
| parent | 5b2e467a7e5e2ffbb0cbbf2557283be891d8206b (diff) | |
Delete manuals!
Good riddance! These are hosted on files.dthompson.us now!
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diff --git a/manuals/chickadee/Shaders.html b/manuals/chickadee/Shaders.html deleted file mode 100644 index 505e031..0000000 --- a/manuals/chickadee/Shaders.html +++ /dev/null @@ -1,405 +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>Shaders (The Chickadee Game Toolkit)</title> - -<meta name="description" content="Shaders (The Chickadee Game Toolkit)" /> -<meta name="keywords" content="Shaders (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="Graphics.html" rel="up" title="Graphics" /> -<link href="Framebuffers.html" rel="next" title="Framebuffers" /> -<link href="Buffers.html" rel="prev" title="Buffers" /> -<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="Shaders"></span><div class="header"> -<p> -Next: <a href="Framebuffers.html" accesskey="n" rel="next">Framebuffers</a>, Previous: <a href="Buffers.html" accesskey="p" rel="prev">Buffers</a>, Up: <a href="Graphics.html" accesskey="u" rel="up">Graphics</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="Shaders-1"></span><h4 class="subsection">5.3.13 Shaders</h4> - -<p>Shaders are programs that the GPU can evaluate that allow the -programmer to completely customized the final output of a GPU draw -call. The <code>(chickadee graphics shader)</code> module provides an API for -building custom shaders. -</p> -<p>Shaders are written in the OpenGL Shading Language, or GLSL for short. -Chickadee aspires to provide a domain specific language for writing -shaders in Scheme, but we are not there yet. -</p> -<p>Shader programs consist of two components: A vertex shader and a -fragment shader. A vertex shader receives vertex data (position -coordinates, texture coordinates, normals, etc.) and transforms them -as desired, whereas a fragment shader controls the color of each -pixel. -</p> -<p>Sample vertex shader: -</p> -<div class="example"> -<pre class="verbatim">#version 130 - -in vec2 position; -in vec2 tex; -out vec2 fragTex; -uniform mat4 mvp; - -void main(void) { - fragTex = tex; - gl_Position = mvp * vec4(position.xy, 0.0, 1.0); -} -</pre></div> - -<p>Sample fragment shader: -</p> -<div class="example"> -<pre class="verbatim">#version 130 - -in vec2 fragTex; -uniform sampler2D colorTexture; - -void main (void) { - gl_FragColor = texture2D(colorTexture, fragTex); -} -</pre></div> - -<p>This manual will not cover GLSL features and syntax as there is lots -of information already available about this topic. -</p> -<p>One way to think about rendering with shaders, and the metaphor -Chickadee uses, is to think about it as a function call: The shader is -a function, and it is applied to some “attributes” (positional -arguments), and some “uniforms” (keyword arguments). -</p> -<div class="lisp"> -<pre class="lisp"><span class="syntax-open">(</span><span class="syntax-special">define</span> <span class="syntax-symbol">my-shader</span> <span class="syntax-open">(</span><span class="syntax-symbol">load-shader</span> <span class="syntax-string">"vert.glsl"</span> <span class="syntax-string">"frag.glsl"</span><span class="syntax-close">)</span><span class="syntax-close">)</span> -<span class="syntax-open">(</span><span class="syntax-special">define</span> <span class="syntax-symbol">vertices</span> <span class="syntax-open">(</span><span class="syntax-symbol">make-vertex-array</span> <span class="syntax-symbol">...</span><span class="syntax-close">)</span><span class="syntax-close">)</span> -<span class="syntax-open">(</span><span class="syntax-symbol">shader-apply</span> <span class="syntax-symbol">my-shader</span> <span class="syntax-symbol">vertices</span> <span class="syntax-keyword">#:color</span> <span class="syntax-symbol">red</span><span class="syntax-close">)</span> -</pre></div> - -<p>See <a href="Rendering-Engine.html">Rendering Engine</a> for more details about the <code>shader-apply</code> -procedure. -</p> -<p>Shaders are incredibly powerful tools, and there’s more information -about them than we could ever fit into this manual, so we highly -recommend searching the web for more information and examples. What -we can say, though, is how to use our API: -</p> -<dl> -<dt id="index-strings_002d_003eshader">Procedure: <strong>strings->shader</strong> <em>vertex-source fragment-source</em></dt> -<dd><p>Compile <var>vertex-source</var>, the GLSL code for the vertex shader, and -<var>fragment-source</var>, the GLSL code for the fragment shader, into a -GPU shader program. -</p></dd></dl> - -<dl> -<dt id="index-load_002dshader">Procedure: <strong>load-shader</strong> <em>vertex-source-file fragment-source-file</em></dt> -<dd><p>Compile the GLSL source code within <var>vertex-source-file</var> and -<var>fragment-source-file</var> into a GPU shader program. -</p></dd></dl> - -<dl> -<dt id="index-make_002dshader">Procedure: <strong>make-shader</strong> <em>vertex-port fragment-port</em></dt> -<dd><p>Read GLSL source from <var>vertex-port</var> and <var>fragment-port</var> and -compile them into a GPU shader program. -</p></dd></dl> - -<dl> -<dt id="index-shader_003f">Procedure: <strong>shader?</strong> <em>obj</em></dt> -<dd><p>Return <code>#t</code> if <var>obj</var> is a shader. -</p></dd></dl> - -<dl> -<dt id="index-null_002dshader">Variable: <strong>null-shader</strong></dt> -<dd><p>Represents the absence shader program. -</p></dd></dl> - -<dl> -<dt id="index-shader_002duniform">Procedure: <strong>shader-uniform</strong> <em>shader name</em></dt> -<dd><p>Return the metadata for the uniform <var>name</var> in <var>shader</var>. -</p></dd></dl> - -<dl> -<dt id="index-shader_002duniforms">Procedure: <strong>shader-uniforms</strong> <em>shader</em></dt> -<dd><p>Return a hash table of uniforms for <var>shader</var>. -</p></dd></dl> - -<dl> -<dt id="index-shader_002dattributes">Procedure: <strong>shader-attributes</strong> <em>shader</em></dt> -<dd><p>Return a hash table of attributes for <var>shader</var>. -</p></dd></dl> - -<dl> -<dt id="index-shader_002duniform_002dset_0021">Procedure: <strong>shader-uniform-set!</strong> <em>shader uniform value</em></dt> -</dl> - -<span id="Attributes"></span><h4 class="subsubsection">5.3.13.1 Attributes</h4> - -<dl> -<dt id="index-attribute_003f">Procedure: <strong>attribute?</strong> <em>obj</em></dt> -<dd><p>Return <code>#t</code> if <var>obj</var> is an attribute. -</p></dd></dl> - -<dl> -<dt id="index-attribute_002dname">Procedure: <strong>attribute-name</strong> <em>attribute</em></dt> -<dd><p>Return the variable name of <var>attribute</var>. -</p></dd></dl> - -<dl> -<dt id="index-attribute_002dlocation">Procedure: <strong>attribute-location</strong> <em>attribute</em></dt> -<dd><p>Return the binding location of <var>attribute</var>. -</p></dd></dl> - -<dl> -<dt id="index-attribute_002dtype">Procedure: <strong>attribute-type</strong> <em>attribute</em></dt> -<dd><p>Return the data type of <var>attribute</var>. -</p></dd></dl> - -<span id="Uniforms"></span><h4 class="subsubsection">5.3.13.2 Uniforms</h4> - -<dl> -<dt id="index-uniform_003f">Procedure: <strong>uniform?</strong> <em>obj</em></dt> -<dd><p>Return <code>#t</code> if <var>obj</var> is a uniform. -</p></dd></dl> - -<dl> -<dt id="index-uniform_002dname">Procedure: <strong>uniform-name</strong> <em>uniform</em></dt> -<dd><p>Return the variable name of <var>uniform</var>. -</p></dd></dl> - -<dl> -<dt id="index-uniform_002dtype">Procedure: <strong>uniform-type</strong> <em>uniform</em></dt> -<dd><p>Return the data type of <var>uniform</var>. -</p></dd></dl> - -<dl> -<dt id="index-uniform_002dvalue">Procedure: <strong>uniform-value</strong> <em>uniform</em></dt> -<dd><p>Return the current value of <var>uniform</var>. -</p></dd></dl> - -<span id="User_002dDefined-Shader-Types"></span><h4 class="subsubsection">5.3.13.3 User-Defined Shader Types</h4> - -<p>The shader examples in this manual thus far have only shown uniforms -defined using primitive types. However, GLSL shaders support -user-defined compound structs, such as this one: -</p> -<div class="example"> -<pre class="verbatim">struct Light { - bool enabled; - int type; - vec3 position; - vec3 direction; - vec4 color; - float intensity; - float cutOff; -}; - -uniform Light light; -</pre></div> - -<p>While <code>light</code> is declared as a single uniform in the shader code, -OpenGL translates this into <em>seven</em> uniforms in this case: One -uniform each member of the <code>Light</code> struct. This poses a problem -for sending Scheme data to the GPU. How can compound Scheme data -translate into compound uniform data on the GPU? The answer is with -shader types. Shader types are a special kind of Guile struct that -provide a one-to-one mapping between a Scheme data structure and a -shader struct. -</p> -<p>Some example code will explain this concept best. Here is the Scheme -equivalent of the <code>Light</code> struct: -</p> -<div class="lisp"> -<pre class="lisp"><span class="syntax-open">(</span><span class="syntax-special">define-shader-type</span> <span class="syntax-symbol"><light></span> - <span class="syntax-symbol">make-light</span> - <span class="syntax-symbol">light?</span> - <span class="syntax-open">(</span><span class="syntax-symbol">bool</span> <span class="syntax-symbol">enabled</span> <span class="syntax-symbol">light-enabled?</span><span class="syntax-close">)</span> - <span class="syntax-open">(</span><span class="syntax-symbol">int</span> <span class="syntax-symbol">type</span> <span class="syntax-symbol">light-type</span><span class="syntax-close">)</span> - <span class="syntax-open">(</span><span class="syntax-symbol">float-vec3</span> <span class="syntax-symbol">position</span> <span class="syntax-symbol">light-position</span><span class="syntax-close">)</span> - <span class="syntax-open">(</span><span class="syntax-symbol">float-vec3</span> <span class="syntax-symbol">direction</span> <span class="syntax-symbol">light-direction</span><span class="syntax-close">)</span> - <span class="syntax-open">(</span><span class="syntax-symbol">float-vec4</span> <span class="syntax-symbol">color</span> <span class="syntax-symbol">light-color</span><span class="syntax-close">)</span> - <span class="syntax-open">(</span><span class="syntax-symbol">float</span> <span class="syntax-symbol">intensity</span> <span class="syntax-symbol">light-intensity</span><span class="syntax-close">)</span> - <span class="syntax-open">(</span><span class="syntax-symbol">float</span> <span class="syntax-symbol">cut-off</span> <span class="syntax-symbol">light-cut-off</span><span class="syntax-close">)</span><span class="syntax-close">)</span> -</pre></div> - -<p>The macro <code>define-shader-type</code> closely resembles the familiar -<code>define-record-type</code> from SRFI-9, but with one notable -difference: Each struct field contains type information. The type -must be one of several primitive types (documented below) or another -shader type in the case of a nested structure. -</p> -<p>It is important to note that the names of the shader type fields -<em>must</em> match the names of the struct members in the GLSL code, -otherwise Chickadee will be unable to perform the proper translation. -</p> -<p>As of this writing, this interface is new and experimental. It -remains to be seen if this model is robust enough for all use-cases. -</p> -<p>Primitive data types: -</p> -<dl> -<dt id="index-bool">Variable: <strong>bool</strong></dt> -<dd><p>Either <code>#t</code> or <code>#f</code>. -</p></dd></dl> - -<dl> -<dt id="index-int">Variable: <strong>int</strong></dt> -<dd><p>An integer. -</p></dd></dl> - -<dl> -<dt id="index-unsigned_002dint">Variable: <strong>unsigned-int</strong></dt> -<dd><p>An unsigned integer. -</p></dd></dl> - -<dl> -<dt id="index-float">Variable: <strong>float</strong></dt> -<dd><p>A floating point number. -</p></dd></dl> - -<dl> -<dt id="index-float_002dvec2">Variable: <strong>float-vec2</strong></dt> -<dd><p>A 2D vector (see <a href="Vectors.html">Vectors</a>.) -</p></dd></dl> - -<dl> -<dt id="index-float_002dvec3">Variable: <strong>float-vec3</strong></dt> -<dd><p>A 3D vector (see <a href="Vectors.html">Vectors</a>.) -</p></dd></dl> - -<dl> -<dt id="index-float_002dvec4">Variable: <strong>float-vec4</strong></dt> -<dd><p>A color (see <a href="Colors.html">Colors</a>) or rectangle (see <a href="Rectangles.html">Rectangles</a>.) -</p></dd></dl> - -<dl> -<dt id="index-mat3">Variable: <strong>mat3</strong></dt> -<dd><p>A 3x3 matrix (see <a href="Matrices.html">Matrices</a>.) -</p></dd></dl> - -<dl> -<dt id="index-mat4">Variable: <strong>mat4</strong></dt> -<dd><p>A 4x4 matrix (see <a href="Matrices.html">Matrices</a>.) -</p></dd></dl> - -<dl> -<dt id="index-sampler_002d2d">Variable: <strong>sampler-2d</strong></dt> -<dd><p>A texture (see <a href="Textures.html">Textures</a>.) -</p></dd></dl> - -<dl> -<dt id="index-sampler_002dcube">Variable: <strong>sampler-cube</strong></dt> -<dd><p>A cube map (see <a href="Textures.html">Textures</a>.) -</p></dd></dl> - -<dl> -<dt id="index-local_002dfield">Variable: <strong>local-field</strong></dt> -<dd><p>A special type that means that the data is for the client-side -(Scheme-side) only and should not be sent to the GPU. Any object may -be stored in a local field. -</p></dd></dl> - -<dl> -<dt id="index-define_002dshader_002dtype">Syntax: <strong>define-shader-type</strong> <em><name> constructor predicate (field-type field-name [field-getter] [field-setter]) …</em></dt> -<dd> -<p>Define a new shader data type called <var><name></var>. -</p> -<p>Instances of this data type are created by calling the -<var>constructor</var> procedure. This procedure maps each field to a -keyword argument. A shader data type with the fields <code>foo</code>, -<code>bar</code>, and <code>baz</code> would have a constructor that accepts the -keyword arguments <code>#:foo</code>, <code>#:bar</code>, and <code>#:baz</code>. -</p> -<p>A procedure named <var>predicate</var> will test if an object is a -<var><name></var> shader data type. -</p> -<p>Fields follow the format <code>(field-type field-name [field-getter] -[field-setter])</code>. <var>field-type</var> and <var>field-name</var> are required -for each field, but <var>field-getter</var> and <var>field-setter</var> are -optional. -</p> -</dd></dl> - -<dl> -<dt id="index-shader_002ddata_002dtype_003f">Procedure: <strong>shader-data-type?</strong> <em>obj</em></dt> -<dd><p>Return <code>#t</code> if <var>obj</var> is a shader data type object. -</p></dd></dl> - -<hr /> -<div class="header"> -<p> -Next: <a href="Framebuffers.html" accesskey="n" rel="next">Framebuffers</a>, Previous: <a href="Buffers.html" accesskey="p" rel="prev">Buffers</a>, Up: <a href="Graphics.html" accesskey="u" rel="up">Graphics</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> |