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authorDavid Thompson <dthompson@vistahigherlearning.com>2020-04-08 17:10:29 -0400
committerDavid Thompson <dthompson@vistahigherlearning.com>2020-04-08 17:10:29 -0400
commite7d470e954d0a17ab1b2fe0065f46f78475272f9 (patch)
treeca4d9c00789f41dbbdbac33151824812dad879f7 /manuals/chickadee/Shaders.html
parentb660cbb5287f7cdcb6cebaba72afe8fc7d512616 (diff)
Add chickade 0.5.0 stuff.
Diffstat (limited to 'manuals/chickadee/Shaders.html')
-rw-r--r--manuals/chickadee/Shaders.html201
1 files changed, 163 insertions, 38 deletions
diff --git a/manuals/chickadee/Shaders.html b/manuals/chickadee/Shaders.html
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@@ -1,6 +1,6 @@
<!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
+<!-- Copyright (C) 2017-2020 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
@@ -18,7 +18,7 @@ Foundation Web site at http://www.gnu.org/licenses/fdl.html.
The document was typeset with
http://www.texinfo.org/ (GNU Texinfo).
-->
-<!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ -->
+<!-- Created by GNU Texinfo 6.6, 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>
@@ -32,29 +32,20 @@ http://www.texinfo.org/ (GNU Texinfo).
<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="Scripting.html#Scripting" rel="next" title="Scripting">
+<link href="Audio.html#Audio" rel="next" title="Audio">
<link href="Buffers.html#Buffers" rel="prev" title="Buffers">
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@@ -89,14 +80,12 @@ ul.no-bullet {list-style: none}
</head>
<body lang="en">
-<a name="Shaders"></a>
-<div class="header">
+<span id="Shaders"></span><div class="header">
<p>
Previous: <a href="Buffers.html#Buffers" accesskey="p" rel="prev">Buffers</a>, Up: <a href="Graphics.html#Graphics" accesskey="u" rel="up">Graphics</a> &nbsp; [<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="Shaders-1"></a>
-<h4 class="subsection">2.3.12 Shaders</h4>
+<span id="Shaders-1"></span><h4 class="subsection">2.3.14 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
@@ -165,92 +154,228 @@ recommend searching the web for more information and examples. What
we can say, though, is how to use our API:
</p>
<dl>
-<dt><a name="index-strings_002d_003eshader"></a>Procedure: <strong>strings-&gt;shader</strong> <em>vertex-source fragment-source</em></dt>
+<dt id="index-strings_002d_003eshader">Procedure: <strong>strings-&gt;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><a name="index-load_002dshader"></a>Procedure: <strong>load-shader</strong> <em>vertex-source-file fragment-source-file</em></dt>
+<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><a name="index-make_002dshader"></a>Procedure: <strong>make-shader</strong> <em>vertex-port fragment-port</em></dt>
+<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><a name="index-shader_003f"></a>Procedure: <strong>shader?</strong> <em>obj</em></dt>
+<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><a name="index-null_002dshader"></a>Variable: <strong>null-shader</strong></dt>
+<dt id="index-null_002dshader">Variable: <strong>null-shader</strong></dt>
<dd><p>Represents the absence shader program.
</p></dd></dl>
<dl>
-<dt><a name="index-shader_002duniform"></a>Procedure: <strong>shader-uniform</strong> <em>shader name</em></dt>
+<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><a name="index-shader_002duniforms"></a>Procedure: <strong>shader-uniforms</strong> <em>shader</em></dt>
+<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><a name="index-shader_002dattributes"></a>Procedure: <strong>shader-attributes</strong> <em>shader</em></dt>
+<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><a name="index-uniform_003f"></a>Procedure: <strong>uniform?</strong> <em>obj</em></dt>
+<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">2.3.14.1 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">2.3.14.2 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><a name="index-uniform_002dname"></a>Procedure: <strong>uniform-name</strong> <em>uniform</em></dt>
+<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><a name="index-uniform_002dtype"></a>Procedure: <strong>uniform-type</strong> <em>uniform</em></dt>
+<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><a name="index-uniform_002dvalue"></a>Procedure: <strong>uniform-value</strong> <em>uniform</em></dt>
+<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">2.3.14.3 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 DirectionalLight {
+ vec3 direction;
+ vec3 ambient;
+ vec3 diffuse;
+ vec3 specular;
+};
+
+uniform DirectionalLight light;
+</pre></div>
+
+<p>While <code>light</code> is declared as a single uniform in the shader code,
+OpenGL translates this into <em>four</em> uniforms in this case: One
+uniform each member of the <code>DirectionalLight</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>DirectionalLight</code> struct:
+</p>
+<div class="example">
+<pre class="example">(define-shader-type &lt;directional-light&gt;
+ make-directional-light
+ directional-light?
+ (float-vec3 direction directional-light-direction)
+ (float-vec3 ambient directional-light-ambient)
+ (float-vec3 diffuse directional-light-diffuse)
+ (float-vec3 specular directional-light-specular)
+ (float shininess directional-light-shininess))
+</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><a name="index-uniform_002ddefault_002dvalue"></a>Procedure: <strong>uniform-default-value</strong> <em>uniform</em></dt>
-<dd><p>Return the default value of <var>uniform</var>.
+<dt id="index-bool">Variable: <strong>bool</strong></dt>
+<dd><p>Either <code>#t</code> or <code>#f</code>.
</p></dd></dl>
<dl>
-<dt><a name="index-attribute_003f"></a>Procedure: <strong>attribute?</strong> <em>obj</em></dt>
-<dd><p>Return <code>#t</code> if <var>obj</var> is an attribute.
+<dt id="index-int">Variable: <strong>int</strong></dt>
+<dd><p>An integer.
</p></dd></dl>
<dl>
-<dt><a name="index-attribute_002dname"></a>Procedure: <strong>attribute-name</strong> <em>attribute</em></dt>
-<dd><p>Return the variable name of <var>attribute</var>.
+<dt id="index-unsigned_002dint">Variable: <strong>unsigned-int</strong></dt>
+<dd><p>An unsigned integer.
</p></dd></dl>
<dl>
-<dt><a name="index-attribute_002dlocation"></a>Procedure: <strong>attribute-location</strong> <em>attribute</em></dt>
-<dd><p>Return the binding location of <var>attribute</var>.
+<dt id="index-float">Variable: <strong>float</strong></dt>
+<dd><p>A floating point number.
</p></dd></dl>
<dl>
-<dt><a name="index-attribute_002dtype"></a>Procedure: <strong>attribute-type</strong> <em>attribute</em></dt>
-<dd><p>Return the data type of <var>attribute</var>.
+<dt id="index-float_002dvec2">Variable: <strong>float-vec2</strong></dt>
+<dd><p>A 2D vector (see <a href="Vectors.html#Vectors">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">Vectors</a>.)
+</p></dd></dl>
+
+<dl>
+<dt id="index-float_002dvec4">Variable: <strong>float-vec4</strong></dt>
+<dd><p>A color.
+</p></dd></dl>
+
+<dl>
+<dt id="index-mat4">Variable: <strong>mat4</strong></dt>
+<dd><p>A matrix (see <a href="Matrices.html#Matrices">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">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>&lt;name&gt; constructor predicate (field-type field-name [field-getter] [field-setter]) &hellip;</em></dt>
+<dd>
+<p>Define a new shader data type called <var>&lt;name&gt;</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>&lt;name&gt;</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>
generated by cgit v1.2.3 (git 2.25.4) at 2024-09-28 23:07:30 +0000