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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<head>

<title>arrow</title>

<!--

.style1 {font-size: x-large}

-->

</style>

<!--

.style2 {font-size: xx-large}

-->

</style>

<!--

function MM_jumpMenu(targ,selObj,restore){ //v3.0

eval(targ+".location='"+selObj.options[selObj.selectedIndex].value+"'");

if (restore) selObj.selectedIndex=0;

}

//-->

</script>

</head>

<body>

<tr>

If you're new to Python

and VPython: <a href="VisualIntro.html">Introduction</a>

A VPython <a href="VPython_Intro.pdf" target="_blank">tutorial</a>

<a href="primitives.html">Pictures</a> of 3D objects

Choose an object:

<option>Choose an object</option>

<option value="cylinder.html">Overview</option>

<option value="arrow.html">arrow</option>

<option value="convex.html">convex</option>

<option value="curve.html">curve</option>

<option value="cylinder.html">cylinder</option>

<option value="ellipsoid.html">ellipsoid</option>

<option value="extrusion.html">extrusion</option>

<option value="faces.html">faces</option>

<option value="frame.html">frame</option>

<option value="helix.html">helix</option>

<option value="label.html">label</option>

<option value="lights.html">lights</option>

<option value="points.html">points</option>

<option value="pyramid.html">pyramid</option>

<option value="sphere.html">sphere</option>

</select>

Work with objects:

<option>Choose an option</option>

<option value="color.html">Color/Opacity</option>

<option value="materials.html">Materials/Textures</option>

<option value="shapes.html">Shapes Library</option>

<option value="paths.html">Paths Library</option>

<option value="defaults.html">Defaults</option>

<option value="rate.html">Animation Speed</option>

<option value="rotation.html">Rotations</option>

<option value="options.html">Additional Options</option>

<option value="delete.html">Delete an Object</option>

<option value="controls.html">Buttons/Sliders</option>

<option value="graph.html">Graphs</option>

<option value="lights.html">Lighting</option>

<option value="files.html">Read/Write Files</option>

<option value="trail.html">Leaving a Trail</option>

<option value="vector.html">Vector Operations </option>

<option value="factorial.html">factorial/combin</option>

</select>

Windows &amp Events:

<option>Choose a topic</option>

<option value="display.html">Windows</option>

<option value="mouse.html">Mouse Events</option>

<option value="mouse_click.html">   Mouse Click</option>

<option value="mouse_drag.html">   Mouse Drag</option>

<option value="keyboard.html">Keyboard Events</option>

</select>

What's new in <a href="new_features.html">Visual 5</a>

<a href="http://vpython.org" target="_blank">VPython web site</a>

<a href="license.txt" target="_blank">Visual license</a>

<a href="http://www.python.org" target="_blank">Python web site</a>

<a href="http://www.python.org/doc/2.5.2/lib/module-math.html" target="_blank">Math module</a> (sqrt etc.)

<a href="http://www.scipy.org/Documentation" target="_blank">Numpy module</a> (arrays) </td>

<tr>

<td width="77%"><div align="center">arrow</div></td>

</tr>

</table>

<div>

<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:

<div>

pointer = arrow(pos=(0,2,1), axis=(5,0,0), shaftwidth=1)

The arrow object has the following attributes and

default values, like those for cylinders: pos (0,0,0), x (0), y(0), z(0), axis (1,0,0), length (1), color (1,1,1)

which is color.white, red (1), green (1), blue (1),

opacity (1), <a href="materials.html">material</a>,

and up (0,1,0).

As with <a href="box.html">box</a>, the up attribute

is significant for arrow because the shaft and head have square

cross sections, and setting the up attribute

rotates the arrow about its axis. Additional arrow attributes:

shaftwidth By default, shaftwidth

= 0.1*(length of arrow)

headwidth By default, headwidth

= 2*shaftwidth

headlength By default, headlength

= 3*shaftwidth

Assigning shaftwidth = 0 makes it be the default (0.1 times the length of the arrow). If you don't explicitly set headwidth or headlength, its length is based as shown above on shaftwidth (either the default or whatever value you specify for shaftwidth). If headlength 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.

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 shaftwidth and headwidth not

change as the arrow gets very short or very long, set fixedwidth

= True.

In this case the only adjustment that is made is that headlength 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.

Note that the pos 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.

If you include make_trail=True 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">Leaving a Trail</a>.

See description of <a href="options.html">Additional

Attributes</a> available for all 3D display objects.

</div>

</td>

</tr>

<tr>

</tr>

</table>

</body>

</html>

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