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From: sfeam <sfeam@users.sourceforge.net>
Newsgroups: comp.graphics.apps.gnuplot
Subject: Re: Postscript fill pattern broken?
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Date: Sun, 17 Jul 2011 09:32 -0700
Organization: gnuplot development team
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Ingo Thies wrote:

> Hi,
> 
> I have noticed some strange behaviour with fill patterns in
> Postscript. I don't know since when it is present, but at least
> gnuplot 4.4 or later (CVS version from July) seems to be affected.
> 
> When I try to use pattern fill in Postscript the pattern for
> fillecurves appears to be extremely pixeled, rather than smooth as in
> the style test page.

Your test script produces an acceptable plot when run here.

I suspect you have hit the well known long-standing bug in ghostscript
that fails to correctly render pattern fill if antialiasing is enabled.
Try turning off antialiasing in your viewer, or try sending the
file to a real postscript printer rather than rendering it in 
ghostscript.

	Ethan

> I am wondering how the patterns on the test page (i.e. with the
> command "test") are actually created. But obviously not using the
> actual commands for pattern-filled rectangles.
> 
> Here is an example script (note that the current gnuplot syntax only
> works with data-based curves rather than functions for fill between
> two curves; for this reason 'set table' is used. If there is an easier
> way, please describe this in the manual, if not already done so):
> 
> reset
> set term push
> set term postscript eps size 15cm,10cm "Helvetica" 20
> set output 'testfill.eps'
> set samples 100
> set xrange [-2.*pi:+2.*pi]
> set yrange [-1.1:2.4]
> set table 'tmp.asc'
> plot sin(x)+0.5
> unset table
> set style fill pattern 4
> plot 'tmp.asc' u 1:($2-0.5):($2+0.5) w filledcu
> unset output
> set term pop
> 
> I would have expected that "fill pattern" would draw lines, but
> actually a pixeled pattern is used (use the magnifying function in
> ghostview). But please note that the sample pattern in the key looks
> OK, only the plotted pattern looks chunky.
> 
> Is there a workaround, or is this an old and not yet resolved bug?
> 
> Best whishes,
> 
> Ingo