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
|
<!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>Viewports (The Chickadee Game Toolkit)</title>
<meta name="description" content="Viewports (The Chickadee Game Toolkit)">
<meta name="keywords" content="Viewports (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="Rendering-Engine.html" rel="next" title="Rendering Engine">
<link href="Framebuffers.html" rel="prev" title="Framebuffers">
<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="Viewports"></span><div class="header">
<p>
Next: <a href="Rendering-Engine.html" accesskey="n" rel="next">Rendering Engine</a>, Previous: <a href="Framebuffers.html" accesskey="p" rel="prev">Framebuffers</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="Viewports-1"></span><h4 class="subsection">2.3.11 Viewports</h4>
<p>A viewport represents a subset of the screen (or framebuffer). When
rendering a frame, the resulting image will only appear within that
viewport. These aren’t often needed, and Chickadee’s default viewport
occupies the entire screen, but there are certain situations where
they are useful. For example, a split-screen multiplayer game may
render to two different viewports, each occupying a different half of
the screen. For information about how to set the current viewport,
see <code>with-viewport</code> in <a href="Rendering-Engine.html">Rendering Engine</a>.
</p>
<p>The <code>(chickadee graphics viewport)</code> module provides the following
API:
</p>
<dl>
<dt id="index-make_002dviewport">Procedure: <strong>make-viewport</strong> <em>x y width height [#:clear-color] [#:clear-flags]</em></dt>
<dd>
<p>Create a viewport that covers an area of the window starting from
coordinates (<var>x</var>, <var>y</var>) and spanning <var>width</var> <code>x</code>
<var>height</var> pixels. Fill the viewport with <var>clear-color</var> when
clearing the screen. Clear the buffers denoted by the list of symbols
in <var>clear-flags</var>.
</p>
<p>Possible values for <var>clear-flags</var> are <var>color-buffer</var>,
<var>depth-buffer</var>, <var>accum-buffer</var>, and <var>stencil-buffer</var>.
</p></dd></dl>
<dl>
<dt id="index-viewport_003f">Procedure: <strong>viewport?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a viewport.
</p></dd></dl>
<dl>
<dt id="index-viewport_002dx">Procedure: <strong>viewport-x</strong> <em>viewport</em></dt>
<dd><p>Return the left edge of <var>viewport</var>.
</p></dd></dl>
<dl>
<dt id="index-viewport_002dy">Procedure: <strong>viewport-y</strong> <em>viewport</em></dt>
<dd><p>Return the bottom edge of <var>viewport</var>.
</p></dd></dl>
<dl>
<dt id="index-viewport_002dwidth">Procedure: <strong>viewport-width</strong> <em>viewport</em></dt>
<dd><p>Return the width of <var>viewport</var>.
</p></dd></dl>
<dl>
<dt id="index-viewport_002dheight">Procedure: <strong>viewport-height</strong> <em>viewport</em></dt>
<dd><p>Return the height of <var>viewport</var>.
</p></dd></dl>
<dl>
<dt id="index-viewport_002dclear_002dcolor">Procedure: <strong>viewport-clear-color</strong> <em>viewport</em></dt>
<dd><p>Return the clear color for <var>viewport</var>.
</p></dd></dl>
<dl>
<dt id="index-viewport_002dclear_002dflags">Procedure: <strong>viewport-clear-flags</strong> <em>viewport</em></dt>
<dd><p>Return the list of clear flags for <var>viewport</var>.
</p></dd></dl>
</body>
</html>
|
