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diff --git a/manuals/chickadee/Shaders.html b/manuals/chickadee/Shaders.html index 70173a4..9d3e555 100644 --- a/manuals/chickadee/Shaders.html +++ b/manuals/chickadee/Shaders.html @@ -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 David Thompson davet@gnu.org +<!-- 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 @@ -13,6 +13,8 @@ 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). --> @@ -30,8 +32,8 @@ 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="Framebuffers.html#Framebuffers" rel="next" title="Framebuffers"> -<link href="Vertex-Arrays.html#Vertex-Arrays" rel="prev" title="Vertex Arrays"> +<link href="Scripting.html#Scripting" rel="next" title="Scripting"> +<link href="Buffers.html#Buffers" rel="prev" title="Buffers"> <style type="text/css"> <!-- a.summary-letter {text-decoration: none} @@ -90,18 +92,172 @@ ul.no-bullet {list-style: none} <a name="Shaders"></a> <div class="header"> <p> -Next: <a href="Framebuffers.html#Framebuffers" accesskey="n" rel="next">Framebuffers</a>, Previous: <a href="Vertex-Arrays.html#Vertex-Arrays" accesskey="p" rel="prev">Vertex Arrays</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> +Previous: <a href="Buffers.html#Buffers" accesskey="p" rel="prev">Buffers</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="Shaders-1"></a> -<h4 class="subsection">2.3.9 Shaders</h4> +<h4 class="subsection">2.3.12 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 render 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="example"> +<pre class="example">(define my-shader (load-shader "vert.glsl" "frag.glsl")) +(define vertices (make-vertex-array …)) +(gpu-apply my-shader vertices #:color red) +</pre></div> -<p>Shaders are programs for the GPU to evaluate. They are written in the -OpenGL Shading Language, or GLSL. Chickadee does not currently -provide a Scheme-like domain specific language for writing shaders. -Since shaders must be written in GLSL and not Scheme, they are -considered an advanced feature. +<p>See <a href="Rendering-Engine.html#Rendering-Engine">Rendering Engine</a> for more details about the <code>gpu-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><a name="index-strings_002d_003eshader"></a>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><a name="index-load_002dshader"></a>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> +<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> +<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> +<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> +<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> +<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> +<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> +<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> +<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> +<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> +<dd><p>Return the current value of <var>uniform</var>. +</p></dd></dl> + +<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>. +</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. +</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>. +</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>. +</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>. +</p></dd></dl> + +<hr> +<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> [<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> |