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
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<HTML>
<!-- HTML file produced from file: UserManual.tex --
-- using Hyperlatex v 2.3.1 (c) Otfried Cheong--
-- on Emacs 21.1 (patch 4) "Arches" XEmacs Lucid, Sun Apr 30 20:49:55 2000 -->
<HEAD>
<TITLE>Tao User Manual -- Access Points</TITLE>
<link rel=stylesheet href="../../taomanual.css" type="text/css">
</HEAD><BODY BACKGROUND="bg.gif">
<table width="500" border="0" align="left" cellspacing="2" cellpadding="2"><tr><td class="nav" valign="top"><!-- top panel --><A HREF="UserManual_19.html"><IMG ALT="Up" ALIGN=BOTTOM BORDER=0 SRC="up.gif"></A>
<BR><A HREF="UserManual_19.html">Conceptual Overview</A><BR><IMG width="167" height="1" SRC="trans1x1.gif">
</td><td class="nav" valign="top"><A HREF="UserManual_30.html"><IMG ALT="Back" ALIGN=BOTTOM BORDER=0 SRC="back.gif"></A>
<BR><A HREF="UserManual_30.html">The Information Needed to Create an Instrument</A><BR><IMG width="167" height="1" SRC="trans1x1.gif">
</td><td class="nav" valign="top"><A HREF="UserManual_32.html"><IMG ALT="Forward" ALIGN=BOTTOM BORDER=0 SRC="forward.gif"></A>
<BR><A HREF="UserManual_32.html">Instrument Visualisations</A><BR><IMG width="167" height="1" SRC="trans1x1.gif">
</td></tr><!-- end top panel --><tr><td colspan="3" class="main"><!-- main text --><br><br>
<H2>Access Points</H2>
In order for <B>Tao</B> to provide an interface between instruments and devices
another key object is needed: the <EM>access point</EM><A NAME="1">.</A> Access points
allow forces to be applied to the material and also for the physical
attributes of the material to be read off at <EM>any</EM> point, not just
at the discrete set of points where cells exist. This interpolation facility
is one of the most important as it overcomes some of the limitations associated
with the material being discrete in nature. An example might be trying to
simulate a string being stopped to a particular pitch. Without the ability
to interpolate the position at which the stop is applied it might not be
possible to achieve the desired pitch precisely.
<P><P> <A NAME="2">
<BLOCKQUOTE><CENTER>
<IMG SRC="instrument_coord_system.gif">
</CENTER></BLOCKQUOTE>
<CENTER>The Instrument Coordinate System</CENTER>
</A>
<P><P>In short, all interactions between <B>Tao</B>'s cellular material and the outside
world take place via access points. This is probably a good place to
introduce the notion of the
<EM>instrument coordinate system</EM>.
This coordinate system allows points in the range <I>(0..1, 0..1)</I> to be
specified.
All instruments, regardless of their shape and size use the same
normalised coordinate system as illustrated in figure
<A HREF="#2">*</A>. Of course for some instruments
such as the circular sheet depicted some points (such as point <B>a</B>)
will be invalid. If a script attempts to use such an access point
nothing will happen. If the physical attributes are read off
the instrument at such a point, they will all return values of zero.
<P>Note also that in the case of the string only the <I>x</I> coordinate needs
to be specified.
<P>
<BR></td></tr><!-- end main text --><tr><td class="nav" align="left" valign="top"><!-- bottom matter --><A HREF="UserManual_19.html"><IMG ALT="Up" ALIGN=BOTTOM BORDER=0 SRC="up.gif"></A>
<BR><A HREF="UserManual_19.html">Conceptual Overview</A><BR><IMG width="167" height="1" SRC="trans1x1.gif">
</td><td class="nav" align="left" valign="top"><A HREF="UserManual_30.html"><IMG ALT="Back" ALIGN=BOTTOM BORDER=0 SRC="back.gif"></A>
<BR><A HREF="UserManual_30.html">The Information Needed to Create an Instrument</A><BR><IMG width="167" height="1" SRC="trans1x1.gif">
</td><td class="nav" align="left" valign="top"><!-- bottom matter --><A HREF="UserManual_32.html"><IMG ALT="Forward" ALIGN=BOTTOM BORDER=0 SRC="forward.gif"></A>
<BR><A HREF="UserManual_32.html">Instrument Visualisations</A>
<IMG width="167" height="1" SRC="trans1x1.gif">
</td></tr><!-- end bottom matter -->
<tr><td colspan="3" class="addr"><!-- bottom panel --><ADDRESS><FONT SIZE=-1>©1999,2000 Mark Pearson
<A HREF="mailto:m.pearson@ukonline.co.uk">m.pearson@ukonline.co.uk</A> April 30, 2000</ADDRESS><BR></td></tr><!-- end bottom panel --></table></BODY></HTML>
|
