/usr/share/doc/sketch-doc/sketch/Nested-sweeps.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Copyright (C) 2005 to 2012 Eugene K. Ressler.

This manual is for sketch, version 0.3 (build 7),
Sunday, March 20, 2016, a program that converts descriptions of simple
three-dimensional scenes into line drawings. This version generates
PSTricks or PGF/TikZ code suitable for use with the
TeX document processing system.

Sketch is free software. You can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

Sketch is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with sketch; see the file COPYING.txt.  If not, see
http://www.gnu.org/copyleft.
 -->
<!-- Created by GNU Texinfo 6.1, http://www.gnu.org/software/texinfo/ -->
<head>
<title>Sketch: Nested sweeps</title>

<meta name="description" content="Sketch: Nested sweeps">
<meta name="keywords" content="Sketch: Nested sweeps">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="index.html#Top" rel="start" title="Top">
<link href="Index-of-syntax.html#Index-of-syntax" rel="index" title="Index of syntax">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Swept-objects.html#Swept-objects" rel="up" title="Swept objects">
<link href="Polygon-sweeps.html#Polygon-sweeps" rel="next" title="Polygon sweeps">
<link href="Polyline-sweeps.html#Polyline-sweeps" rel="prev" title="Polyline sweeps">
<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}
-->
</style>


</head>

<body lang="en">
<a name="Nested-sweeps"></a>
<div class="header">
<p>
Next: <a href="Polygon-sweeps.html#Polygon-sweeps" accesskey="n" rel="next">Polygon sweeps</a>, Previous: <a href="Polyline-sweeps.html#Polyline-sweeps" accesskey="p" rel="prev">Polyline sweeps</a>, Up: <a href="Swept-objects.html#Swept-objects" accesskey="u" rel="up">Swept objects</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-syntax.html#Index-of-syntax" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Nested-sweeps-1"></a>
<h4 class="subsection">2.7.3 Nested sweeps</h4>
<p>When the center point of rotation is omitted, 
<a name="index-center-of-rotation-1"></a>
<a name="index-rotation_002c-center-of-1"></a>
the origin is assumed.
When a point has only two coordinates, they are taken as
<em>x</em>&nbsp;and <em>y</em>,&nbsp;with <em>z=0</em> assumed.  A toroid 
<a name="index-toroid"></a>
is therefore obtained with this code.
<a name="index-def-5"></a>
<a name="index-sweep-4"></a>
<a name="index-rotate-6"></a>
</p><pre class="verbatim">  def n_toroid_segs 20   def n_circle_segs 16
  def r_minor 1          def r_major 1.5
  sweep { n_toroid_segs, rotate(360 / n_toroid_segs, [0,1,0]) }
    sweep { n_circle_segs, rotate(360 / n_circle_segs, (r_major,0,0)) } 
      (r_major + r_minor, 0)
</pre><p>For intuition, the idea of the code is to sketch a circle to the right
of the origin in the <em>xy</em>-plane, then rotate that circle &ldquo;out of
the plane&rdquo; about the <em>y</em>-axis to make the final figure.  This
produces the following.  (A view rotation and some axes have been
added.)
</p>
<div align="center"><img src="ex090.png" alt="ex090">
</div>
<p>This example also shows that the swept object may itself be another
<code>sweep</code>.
<a name="index-sweep-5"></a>
<a name="index-nesting_002c-swept-object"></a>
In fact, it may be <em>any</em> <code>sketch</code> expression that results in
a list of one or more points or, alternately, a list of one or more
polylines and polygons.  The latter kind of list can be created with a
<tt>{ }</tt>-enclosed block, perhaps following a 
<a name="index-put-1"></a>
<tt>put</tt> or
<a name="index-repeat-1"></a>
<tt>repeat</tt>.
<a name="index-_007b-_007d_002c-block-drawable-1"></a>
</p>



</body>
</html>
sketch-doc 1:0.3.7-2 / usr / share / doc / sketch-doc / sketch / Nested-sweeps.html
