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
|
<!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
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.
The document was typeset with
http://www.texinfo.org/ (GNU Texinfo).
-->
<!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Tweening (The Chickadee Game Toolkit)</title>
<meta name="description" content="Tweening (The Chickadee Game Toolkit)">
<meta name="keywords" content="Tweening (The Chickadee Game Toolkit)">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<link href="index.html#Top" rel="start" title="Top">
<link href="Index.html#Index" rel="index" title="Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Scripting.html#Scripting" rel="up" title="Scripting">
<link href="Channels.html#Channels" rel="next" title="Channels">
<link href="Scripts.html#Scripts" rel="prev" title="Scripts">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.indentedblock {margin-right: 0em}
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smalllisp {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}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
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">
<a name="Tweening"></a>
<div class="header">
<p>
Next: <a href="Channels.html#Channels" accesskey="n" rel="next">Channels</a>, Previous: <a href="Scripts.html#Scripts" accesskey="p" rel="prev">Scripts</a>, Up: <a href="Scripting.html#Scripting" accesskey="u" rel="up">Scripting</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="Tweening-1"></a>
<h4 class="subsection">2.4.3 Tweening</h4>
<p>Tweening is the process of transitioning something from an initial
state to a final state over a pre-determined period of time. In other
words, tweening is a way to create animation. The <code>tween</code>
procedure can be used within any script like so:
</p>
<div class="example">
<pre class="example">(define x 0)
(script
;; 0 to 100 in 60 ticks of the agenda.
(tween 60 0 100 (lambda (y) (set! x y))))
</pre></div>
<dl>
<dt><a name="index-tween"></a>Procedure: <strong>tween</strong> <em><var>duration</var> <var>start</var> <var>end</var> <var>proc</var> [#:step 1 #:ease <code>smoothstep</code> #:interpolate <code>lerp</code>]</em></dt>
<dd><p>Transition a value from <var>start</var> to <var>end</var> over <var>duration</var>,
sending each succesive value to <var>proc</var>. <var>step</var> controls the
amount of time between each update of the animation.
</p>
<p>To control how the animation goes from the initial to final state, an
“easing” procedure may be specified. By default, the
<code>smoothstep</code> easing is used, which is a more pleasing default
than a simplistic linear function. See <a href="Easings.html#Easings">Easings</a> for a complete list
of available easing procedures.
</p>
<p>The <var>interpolate</var> procedure computes the values in between
<var>start</var> and <var>end</var>. By default, linear interpolation (“lerp”
for short) is used.
</p></dd></dl>
</body>
</html>
|
