1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- 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
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>Rendering Engine (The Chickadee Game Toolkit)</title>
<meta name="description" content="Rendering Engine (The Chickadee Game Toolkit)">
<meta name="keywords" content="Rendering Engine (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="Buffers.html" rel="next" title="Buffers">
<link href="Viewports.html" rel="prev" title="Viewports">
<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="Rendering-Engine"></span><div class="header">
<p>
Next: <a href="Buffers.html" accesskey="n" rel="next">Buffers</a>, Previous: <a href="Viewports.html" accesskey="p" rel="prev">Viewports</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="Rendering-Engine-1"></span><h4 class="subsection">2.3.13 Rendering Engine</h4>
<p>Chickadee defines rendering using a metaphor familiar to Scheme
programmers: procedure application. A shader (see <a href="Shaders.html">Shaders</a>) is
like a procedure for the GPU to apply. Shaders are passed arguments:
A vertex array containing the geometry to render (see <a href="Buffers.html">Buffers</a>) and
zero or more keyword arguments that the shader understands. Similar
to how Scheme has <code>apply</code> for calling procedures, Chickadee
provides <code>shader-apply</code> for calling shaders.
</p>
<p>Additionally, there is some dynamic state that effects how
<code>shader-apply</code> will behave. Things like the current viewport,
framebuffer, and blend mode are stored as dynamic state because it
would be tedious to have to have to specify them each time
<code>shader-apply</code> is called.
</p>
<p>The following procedures and syntax can be found in the
<code>(chickadee graphics)</code> module.
</p>
<dl>
<dt id="index-shader_002dapply">Syntax: <strong>shader-apply</strong> <em>shader vertex-array [#:uniform-key uniform-value …]</em></dt>
<dt id="index-shader_002dapply_002a">Syntax: <strong>shader-apply*</strong> <em>shader vertex-array count [#:uniform-key uniform-value …]</em></dt>
<dd>
<p>Render <var>vertex-array</var> using <var>shader</var> with the uniform values
specified in the following keyword arguments.
</p>
<p>While <code>shader-apply</code> will draw every vertex in <var>vertex-array</var>,
<code>shader-apply*</code> will only draw <var>count</var> vertices.
</p></dd></dl>
<dl>
<dt id="index-shader_002dapply_002finstanced">Syntax: <strong>shader-apply/instanced</strong> <em>shader vertex-array n [#:uniform-key uniform-value …]</em></dt>
<dt id="index-shader_002dapply_002finstanced-1">Syntax: <strong>shader-apply/instanced</strong> <em>shader vertex-array count n [#:uniform-key uniform-value …]</em></dt>
<dd>
<p>Render <var>vertex-array</var> <var>n</var> times using <var>shader</var> with the
uniform values specified in the following keyword arguments.
</p>
<p>Instanced rendering is very beneficial for rendering the same object
many times with only small differences for each one. For example, the
particle effects described in <a href="Particles.html">Particles</a> use instanced rendering.
</p>
<p>While <code>shader-apply/instanced</code> will draw every vertex in
<var>vertex-array</var>, <code>shader-apply*</code> will only draw <var>count</var>
vertices.
</p></dd></dl>
<dl>
<dt id="index-current_002dviewport">Procedure: <strong>current-viewport</strong></dt>
<dd><p>Return the currently bound viewport (see <a href="Viewports.html">Viewports</a>).
</p></dd></dl>
<dl>
<dt id="index-current_002dframebuffer">Procedure: <strong>current-framebuffer</strong></dt>
<dd><p>Return the currently bound framebuffer (see <a href="Framebuffers.html">Framebuffers</a>).
</p></dd></dl>
<dl>
<dt id="index-current_002dblend_002dmode">Procedure: <strong>current-blend-mode</strong></dt>
<dd><p>Return the currently bound blend mode (see <a href="Blending.html">Blending</a>).
</p></dd></dl>
<dl>
<dt id="index-current_002ddepth_002dtest">Procedure: <strong>current-depth-test</strong></dt>
<dd><p>Return <code>#t</code> if depth testing is currently enabled (see <a href="Blending.html">Blending</a>).
</p></dd></dl>
<dl>
<dt id="index-current_002dtexture">Procedure: <strong>current-texture</strong></dt>
<dd><p>Return the currently bound texture (see <a href="Textures.html">Textures</a>).
</p></dd></dl>
<dl>
<dt id="index-current_002dprojection">Procedure: <strong>current-projection</strong></dt>
<dd><p>Return the currently bound projection matrix (see <a href="Matrices.html">Matrices</a>).
</p></dd></dl>
<dl>
<dt id="index-with_002dviewport">Syntax: <strong>with-viewport</strong> <em>viewport body …</em></dt>
<dd><p>Evaluate <var>body</var> with the current viewport bound to <var>viewport</var> (see <a href="Viewports.html">Viewports</a>).
</p></dd></dl>
<dl>
<dt id="index-with_002dframebuffer">Syntax: <strong>with-framebuffer</strong> <em>framebuffer body …</em></dt>
<dd><p>Evaluate <var>body</var> with the current framebuffer bound to
<var>framebuffer</var> (see <a href="Framebuffers.html">Framebuffers</a>).
</p></dd></dl>
<dl>
<dt id="index-with_002dblend_002dmode">Syntax: <strong>with-blend-mode</strong> <em>blend-mode body …</em></dt>
<dd><p>Evaluate <var>body</var> with the current blend mode bound to
<var>blend-mode</var> (see <a href="Blending.html">Blending</a>).
</p></dd></dl>
<dl>
<dt id="index-with_002ddepth_002dtest">Syntax: <strong>with-depth-test</strong> <em>depth-test? body …</em></dt>
<dd><p>Evaluate <var>body</var> with the depth-test disabled if <var>depth-test?</var>
is <code>#f</code>, or enabled otherwise (see <a href="Blending.html">Blending</a>).
</p></dd></dl>
<dl>
<dt id="index-with_002dtexture">Syntax: <strong>with-texture</strong> <em>texture body …</em></dt>
<dd><p>Evaluate <var>body</var> with the current texture bound to <var>texture</var>
(see <a href="Textures.html">Textures</a>).
</p></dd></dl>
<dl>
<dt id="index-with_002dprojection">Syntax: <strong>with-projection</strong> <em>projection body …</em></dt>
<dd><p>Evaluate <var>body</var> with the current projection matrix bound to
<var>projection</var> (see <a href="Matrices.html">Matrices</a>).
</p></dd></dl>
<hr>
<div class="header">
<p>
Next: <a href="Buffers.html" accesskey="n" rel="next">Buffers</a>, Previous: <a href="Viewports.html" accesskey="p" rel="prev">Viewports</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>
|
