blob: e258de2191b7c65575f03b76c54eb044d2edbbdf (
plain)
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
|
<!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>Basics (The Chickadee Game Toolkit)</title>
<meta name="description" content="Basics (The Chickadee Game Toolkit)">
<meta name="keywords" content="Basics (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="Math.html" rel="up" title="Math">
<link href="Vectors.html" rel="next" title="Vectors">
<link href="Math.html" rel="prev" title="Math">
<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="Basics"></span><div class="header">
<p>
Next: <a href="Vectors.html" accesskey="n" rel="next">Vectors</a>, Up: <a href="Math.html" accesskey="u" rel="up">Math</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="Basics-1"></span><h4 class="subsection">2.2.1 Basics</h4>
<dl>
<dt id="index-pi">Variable: <strong>pi</strong></dt>
<dd><p>An essential constant for all trigonometry. Pi is the ratio of a
circle’s circumferences to its diameter. Since pi is an irrational
number, the <var>pi</var> in Chickadee is a mere floating point
approximation that is “good enough.”
</p></dd></dl>
<dl>
<dt id="index-pi_002f2">Variable: <strong>pi/2</strong></dt>
<dd><p>Half of <var>pi</var>.
</p></dd></dl>
<dl>
<dt id="index-2pi">Variable: <strong>2pi</strong></dt>
<dd><p>Twice <var>pi</var>.
</p></dd></dl>
<dl>
<dt id="index-cotan">Procedure: <strong>cotan</strong> <em>z</em></dt>
<dd><p>Return the cotangent of <var>z</var>.
</p></dd></dl>
<dl>
<dt id="index-clamp">Procedure: <strong>clamp</strong> <em>min max x</em></dt>
<dd><p>Restrict <var>x</var> to the inclusive range defined by <var>min</var> and
<var>max</var>. This procedure assumes that <var>min</var> is actually less
than <var>max</var>.
</p></dd></dl>
<dl>
<dt id="index-lerp">Procedure: <strong>lerp</strong> <em>start end alpha</em></dt>
<dd><p>Linearly interpolate the numbers <var>start</var> and <var>end</var> using the
factor <var>alpha</var>, a number in the range [0, 1].
</p></dd></dl>
<dl>
<dt id="index-degrees_002d_003eradians">Procedure: <strong>degrees->radians</strong> <em>degrees</em></dt>
<dd><p>Convert <var>degrees</var> to radians.
</p></dd></dl>
<dl>
<dt id="index-radians_002d_003edegrees">Procedure: <strong>radians->degrees</strong> <em>radians</em></dt>
<dd><p>Convert <var>radians</var> to degrees.
</p></dd></dl>
</body>
</html>
|
