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From: jtc@motcad.portal.com (J.T. Conklin)
Newsgroups: comp.lang.postscript
Subject: Re: Stroking thick lines about arcs
Message-ID: <1991Feb22.171314.5128@motcad.portal.com>
Date: 22 Feb 91 17:13:14 GMT
References: <1991Feb20.161757.24206@motcad.portal.com> <1991Feb21.225435.15664@cbnewsh.att.com>
Organization: Computer Signal Corp., San Ramon, California
Lines: 29

In article <1991Feb21.225435.15664@cbnewsh.att.com> jlp@cbnewsh.att.com (jon.peticolas) writes:
>From article <1991Feb20.161757.24206@motcad.portal.com>, by jtc@motcad.portal.com (J.T. Conklin):
>> I have been observing that stroking an arc with a ``thick'' line results
>> in some areas of white peeking through the line --- especially about the
>> outside perimeter --- on two independant PostScript implementation.
>
>The closepath operator tells postscript that the ends of the path are
>to be joined with a mitered connection. If they are not actually the
>same point, the path will be completed with a straight line. This detail
>is covered in chapter 3 of the Adobe blue book (in my admittedly outdated 
>copy anyway).  Additional line joining details are covered in chapter 10.

Thanks for the hints about closepath, as it solved a different problem with
the example that occurs with Ghostscript --- A little sliver of  white is
not filled at the point where the two ends of the arc should joins. 

The original problem, was that little slivers of white were peeking
through spaced evenly about the perimeter of the circle.  The vendor
of the interpreter in question has admitted the problem and I hope
they will be able to send me a fix soon.

But Jon's point about closepath brings up another newbie type question:
Does a 360 degree close itself automagically, or is an explicit closepath
necessary?

Thanks,

-- 
J.T. Conklin    jtc@motcad.portal.com, ...!portal!motcad!jtc