little_helpers/tikz/sketch-0.2.161/Doc/sketch/Swept-objects.html

   1 <html lang="en">
   2 <head>
   3 <title>Swept objects - Sketch</title>
   4 <meta http-equiv="Content-Type" content="text/html">
   5 <meta name="description" content="Sketch">
   6 <meta name="generator" content="makeinfo 4.7">
   7 <link title="Top" rel="start" href="index.html#Top">
   8 <link rel="up" href="Introduction-by-example.html#Introduction-by-example" title="Introduction by example">
   9 <link rel="prev" href="Repeated-objects.html#Repeated-objects" title="Repeated objects">
  10 <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
  11 <!--
  12 Copyright (C) 2005, 2006, 2007, 2008 Eugene K. Ressler.
  13
  14 This manual is for `sketch', version 0.2 (build 161),
  15 Tuesday, September 08, 2009, a program that converts descriptions of simple
  16 three-dimensional scenes into static drawings. This version generates
  17 `PSTricks' or `PGF/TikZ' code suitable for use with the
  18 TeX document processing system.
  19
  20 `Sketch' is free software; you can redistribute it and/or modify
  21 it under the terms of the GNU General Public License as published by
  22 the Free Software Foundation; either version 3, or (at your option)
  23 any later version.
  24
  25 Sketch is distributed in the hope that it will be useful,
  26 but WITHOUT ANY WARRANTY; without even the implied warranty of
  27 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  28 GNU General Public License for more details.
  29
  30 You should have received a copy of the GNU General Public License
  31 along with `sketch'; see the file COPYING.txt.  If not, see
  32 http://www.gnu.org/copyleft.-->
  33 <meta http-equiv="Content-Style-Type" content="text/css">
  34 <style type="text/css"><!--
  35   pre.display { font-family:inherit }
  36   pre.format  { font-family:inherit }
  37   pre.smalldisplay { font-family:inherit; font-size:smaller }
  38   pre.smallformat  { font-family:inherit; font-size:smaller }
  39   pre.smallexample { font-size:smaller }
  40   pre.smalllisp    { font-size:smaller }
  41   span.sc { font-variant:small-caps }
  42   span.roman { font-family: serif; font-weight: normal; }
  43 --></style>
  44 </head>
  45 <body>
  46 <div class="node">
  47 <p>
  48 <a name="Swept-objects"></a>Previous:&nbsp;<a rel="previous" accesskey="p" href="Repeated-objects.html#Repeated-objects">Repeated objects</a>,
  49 Up:&nbsp;<a rel="up" accesskey="u" href="Introduction-by-example.html#Introduction-by-example">Introduction by example</a>
  50 <hr><br>
  51 </div>
  52
  53 <!-- node-name,  next,  previous,  up -->
  54 <h3 class="section">2.7 Swept objects</h3>
  55
  56 <p><a name="index-swept-object-91"></a><a name="index-sweep-92"></a>Many familiar shapes can be generated by sweeping simpler ones through
  57 space and considering the resulting path, surface, or volume.
  58 <code>Sketch</code> implements this idea in the <tt>sweep</tt> command.
  59 <a name="index-sweep-93"></a><a name="index-rotate-94"></a>
  60 <pre class="verbatim">
  61   def n_segs 8
  62   sweep { n_segs, rotate(180 / n_segs, (0,0,0), [0,0,1]) } (1,0,0)
  63 </pre>
  64 This code sweeps the point (1,0,0)
  65 <a name="index-point-sweep-95"></a><a name="index-swept-point-96"></a>eight times by rotating it
  66 180/8 = 22.5 degrees each time and connecting the resulting
  67 points with line segments.  The <tt>def</tt> used here is a
  68 <dfn>scalar</dfn> definition.
  69 <a name="index-definition_002c-scalar-97"></a><a name="index-scalar-definition-98"></a>References to
  70 <a name="index-reference_002c-scalar-99"></a>scalars have no enclosing brackets at all.
  71
  72 <ul class="menu">
  73 <li><a accesskey="1" href="Point-sweeps.html#Point-sweeps">Point sweeps</a>:                 Swept points make lines and polygons.
  74 <li><a accesskey="2" href="Polyline-sweeps.html#Polyline-sweeps">Polyline sweeps</a>:              Swept lines make surfaces.
  75 <li><a accesskey="3" href="Nested-sweeps.html#Nested-sweeps">Nested sweeps</a>:                Swept sweeps are useful!
  76 <li><a accesskey="4" href="Polygon-sweeps.html#Polygon-sweeps">Polygon sweeps</a>:               Swept polygons make solids...
  77 <li><a accesskey="5" href="Polyline-sweeps-with-closure.html#Polyline-sweeps-with-closure">Polyline sweeps with closure</a>:   and so do closed polyline sweeps.
  78 <li><a accesskey="6" href="Affine-arithmetic.html#Affine-arithmetic">Affine arithmetic</a>:            Sketch useful math expression.
  79 <li><a accesskey="7" href="More-to-learn.html#More-to-learn">More to learn</a>:                Check out the Mobius strip!
  80 </ul>
  81
  82    </body></html>
  83