/usr/share/doc/sketch-doc/sketch/Bugs-and-anomalies.html is in sketch-doc 1:0.3.7-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 | <html lang="en">
<head>
<title>Bugs and anomalies - Sketch</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="Sketch">
<meta name="generator" content="makeinfo 4.13">
<link title="Top" rel="start" href="index.html#Top">
<link rel="up" href="Hidden-surface-removal.html#Hidden-surface-removal" title="Hidden surface removal">
<link rel="prev" href="Statistics.html#Statistics" title="Statistics">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<!--
Copyright (C) 2005 to 2012 Eugene K. Ressler.
This manual is for `sketch', version 0.3 (build 7),
Monday, March 05, 2012, 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.-->
<meta http-equiv="Content-Style-Type" content="text/css">
<style type="text/css"><!--
pre.display { font-family:inherit }
pre.format { font-family:inherit }
pre.smalldisplay { font-family:inherit; font-size:smaller }
pre.smallformat { font-family:inherit; font-size:smaller }
pre.smallexample { font-size:smaller }
pre.smalllisp { font-size:smaller }
span.sc { font-variant:small-caps }
span.roman { font-family:serif; font-weight:normal; }
span.sansserif { font-family:sans-serif; font-weight:normal; }
--></style>
</head>
<body>
<div class="node">
<a name="Bugs-and-anomalies"></a>
<p>
Previous: <a rel="previous" accesskey="p" href="Statistics.html#Statistics">Statistics</a>,
Up: <a rel="up" accesskey="u" href="Hidden-surface-removal.html#Hidden-surface-removal">Hidden surface removal</a>
<hr>
</div>
<!-- node-name, next, previous, up -->
<h5 class="subsubsection">4.4.3.2 Bugs and anomalies</h5>
<p>Polygon and line splitting can both cause anomalies in the output.
<code>PSTricks</code> dash patterns, specified with <code>linestyle=dashed</code>,
<a name="index-linestyle-507"></a>can be disrupted by splitting. This occurs when the depth sort
<a name="index-depth-sort-508"></a>gives up too early and splits a line where it is not really
necessary.
A workaround is to use gray or finely dotted
lines instead. If your drawing is small, you can also edit the
<code>sketch</code> output by hand to merge the pieces of the offending
line.
<p>Another anomaly is tiny (or in degenerate cases not-so-tiny) notches
in the lines that border split polygons. These derive from the way
each polygon is painted: first, all pixels within the boundary are
<dfn>filled</dfn> with color (perhaps white), then the same boundary is
<dfn>stroked</dfn> (a Postscript term) with a line. The result is that
half the line lies inside the boundary and half outside, while the
Painter's algorithm assumes the polygon lies entirely within its
boundary. The notches are due to one polygon fill operation
overwriting the already-drawn inside of the border of another
polygon.<a rel="footnote" href="#fn-1" name="fnd-1"><sup>1</sup></a> One workaround is to make
border lines very thin. In fact <code>linewidth=0pt</code> is guaranteed to
eliminate this problem, though this results in the thinnest line your
output device can draw, which is usually too thin. You might get
lucky by merely reordering things in the input file, which is likely
to move the splits to different places. The only sure-fire solution
is pretty terrible: custom fit <code>special</code> overlay lines (with
<code>\psline</code>) to cover the notches.
<p>Polygon splitting also breaks <code>PSTricks</code> hatch patterns. The
only known workaround is to substitute a solid fill for the hatch.
<div class="footnote">
<hr>
<h4>Footnotes</h4><p class="footnote"><small>[<a name="fn-1" href="#fnd-1">1</a>]</small> I know how to fix this problem, but I don't like my
solution, and I'm interested in yours.</p>
<hr></div>
</body></html>
|