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<!-- InstanceBegin template="/Templates/template.dwt" codeOutsideHTMLIsLocked="false" --><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<!-- InstanceBeginEditable name="doctitle" -->
<title>VPython Help</title>
<!-- InstanceEndEditable -->
<!-- InstanceBeginEditable name="head" -->
<link href="VisualRef.css" rel="stylesheet" type="text/css" />
<style type="text/css">
<!--
.style1 {font-size: x-large}
-->
</style>
<style type="text/css">
<!--
.style2 {font-size: xx-large}
-->
</style>
<!-- InstanceEndEditable -->
</head>
<body>
<div id="wrapper">
<div id="leftmenu">
<p class="Normal"><a href="index.html"> Home</a></p>
<p class="Normal"> If you're new to Python <br />
and VPython: <a href="VisualIntro.html">Introduction</a></p>
<p class="Normal"> A VPython <a href="VPython_Intro.pdf" target="_blank">tutorial</a></p>
<p class="Normal"><a href="videos.html"> Introductory Videos</a></p>
<p class="Normal"><a href="primitives.html"> Pictures</a> of 3D objects</p>
<p> <select id="menu1" onChange="jumpMenu(this)"></select></p>
<p> <select id="menu2" onChange="jumpMenu(this)"></select></p>
<p> <select id="menu3" onChange="jumpMenu(this)"></select></p>
<p class="Normal"><a href="https://vpython.org" target="_blank"> VPython 7 web site</a><br />
<a href="license.txt" target="_blank"> VPython license</a><br />
<br />
</p>
</td>
</div>
<div id="content">
<!-- InstanceBeginEditable name="content" -->
<table width="100%" border="1">
<tr>
<td width="77%"><div align="center"><span class="style1 style2"><font color="#0000A0">arrow</font></span></div></td>
<td width="23%"><img src="images/arrow.jpg" alt="arrow" width="130" height="127" /></td>
</tr>
</table>
<div></div>
<div>
<p class="Normal"> <img src="VisualRef-2.gif" alt="arrow" align="right" /> The arrow object has a straight box-shaped shaft with an arrowhead at one end. The following statement will display an arrow pointing parallel to the x axis:</p>
<div>
<p class="program"> pointer = arrow(pos=vector(0,2,1), axis=vector(5,0,0), shaftwidth=1)</p>
<p class="Normal"> The arrow object has the following attributes and
default values, like those for cylinders: <span class="attribute">pos<font color="#000000"> (0,0,0)</font></span>, <span class="attribute">axis<font color="#000000"> (1,0,0)</font></span>, <span class="attribute">length<font color="#000000"> (1)</font></span>, <span class="attribute">color<font color="#000000"> (1,1,1)
which is color.white</font></span>, <span class="attribute">red<font color="#000000"> (1)</font></span>, <span class="attribute">green<font color="#000000"> (1)</font></span>, <span class="attribute">blue<font color="#000000"> (1)</font></span>,
<span class="attribute">opacity</span> (1),
<span class="attribute">shininess</span> (0.6), <span class="attribute">emissive</span> (False), <a href="textures.html"><strong>texture</strong></a>,
and <span class="attribute">up<font color="#000000"> (0,1,0)</font></span>.
As with <a href="box.html">box</a>, the <span class="attribute">up</span> attribute
is significant for arrow because the shaft and head have square
cross sections, and setting the <em class="program"> </em><span class="attribute">up</span> attribute
rotates the arrow about its axis. Additional arrow attributes:</p>
<p class="attributes"> <span class="attribute">shaftwidth</span> By default, shaftwidth
= 0.1*(length of arrow)</p>
<p class="attributes"> <span class="attribute">headwidth</span> By default, headwidth
= 2*shaftwidth</p>
<p class="attributes"> <span class="attribute">headlength</span> By default, headlength
= 3*shaftwidth</p>
<p class="Normal">Assigning <span class="attribute">shaftwidth = 0</span> makes it be the default (0.1 times the length of the arrow). If you don't explicitly set <span class="attribute">headwidth</span> or <span class="attribute">headlength</span>, its length is based as shown above on <span class="attribute">shaftwidth</span> (either the default or whatever value you specify for <span class="attribute">shaftwidth</span>). If <span class="attribute">headlength</span> becomes larger than half the length of the arrow, or the shaft becomes thinner
than 1/50 the length, the entire arrow is scaled accordingly.</p>
<p class="Normal">This default behavior makes the widths of very short
arrows shrink, and the widths of very long arrows grow (while displaying
the correct total length). If you prefer that <span class="attribute">shaftwidth</span> and <span class="attribute">headwidth</span> not
change as the arrow gets very short or very long, specify the desired <span class="attribute">shaftwidth</span>.
In this case the only adjustment that is made is that <span class="attribute">headlength</span> is
adjusted so that it never gets longer than half the total length,
so that the total length of the arrow is correct. This means that
very short, thick arrows look similar to a thumbtack, with a nearly
flat head.</p>
<p class="Normal">Note that the <span class="attribute">pos</span> attribute
for cylinder, arrow, cone, and pyramid corresponds to one end of the object,
whereas for a box, sphere, or ring it corresponds to the center of the object. </p>
<p class="Normal">If you include <span class="attribute">make_trail=True</span> when you create the object, a trail will be left behind the object as you move it. For related options, see <a href="trail.html"><strong>Leaving a Trail</strong></a>.</p>
<p class="Normal">See <a href="rotation.html"><strong>Rotating an Object</strong></a> for an easy way to change the orientation of an object.</p>
<p class="Normal">See description of <a href="options.html">Additional
Attributes</a> available for all 3D display objects.</p>
<p class="Normal"> </p>
</div>
</div>
<div> </div>
<!-- InstanceEndEditable -->
</div>
</div>
</body>
<script type="text/javascript" language="javascript" src="navigation.js"></script>
<!-- InstanceEnd --></html>