[metapost] Feature Request: Get envelope of path stroked with arbitrary pen

Daniel H. Luecking luecking at uark.edu
Fri Feb 9 19:44:59 CET 2018

It has always (as far as I know) been possible to get the

envelope of a polygonal pen by setting tracingspecs positive

and examining the .log file. Not sure how long envelope as

an operator has been available. Probably just as long, but

in secret.

As already mentioned, metapost doesn't do envelopes for

pencircle. Luigi's example approximates an elliptical pen by

a polygonal one, which is probably good enough if one chooses

the approximation correctly (e.g., one might want to pick

points where tangent directions of the ellipse match directions

of key points of the path being stroked.)


Daniel H. Luecking [luecking at uark.edu]
Department of Mathematical Sciences
1 University of Arkansas
Fayetteville, AR, USA 72701-1201

From: metapost <metapost-bounces at tug.org> on behalf of luigi scarso <luigi.scarso at gmail.com>
Sent: Friday, February 9, 2018 7:19 AM
Cc: MetaPost List
Subject: Re: [metapost] Feature Request: Get envelope of path stroked with arbitrary pen

On Fri, Feb 9, 2018 at 1:58 PM, Hans Hagen <pragma at wxs.nl> wrote:
> On 2/9/2018 1:11 PM, Karel wrote:
>> Nice, Luigi,
>> but the envelope seems to be quite new and not yet documented in mp
>> manual?
> it's more "old and still experimental" awaiting to be tested before being
> declared a documented feature
I will add  a paragraph for the next texlive.

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