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+<html lang="en">
+<head>
+<title>Bugs and anomalies - Sketch</title>
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+Copyright (C) 2005, 2006, 2007, 2008 Eugene K. Ressler.
+
+This manual is for `sketch', version 0.2 (build 131),
+Saturday, August 09, 2008, a program that converts descriptions of simple
+three-dimensional scenes into static 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,
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+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+<a name="Bugs-and-anomalies"></a>Previous:&nbsp;<a rel="previous" accesskey="p" href="Statistics.html#Statistics">Statistics</a>,
+Up:&nbsp;<a rel="up" accesskey="u" href="Hidden-surface-removal.html#Hidden-surface-removal">Hidden surface removal</a>
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+<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-499"></a>can be disrupted by splitting. This occurs when the depth sort
+<a name="index-depth-sort-500"></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>
+
+ <p><hr></div>
+
+ </body></html>
+