[metapost] envelope

[Daniel H. Luecking]

Nicola:

The syntax is 
   envelope <polygonal pen> of <path primary>

For example, 
  path p;
  p := envelope pensquare of (up--left);

It returns the path which, when filled, produces the effect of stroking 
the pen along the path. Elliptical pens (e.g., pencircle) produce an error.

Stroking an elliptical pen is simply passed on to PostScript. But polygonal 
pens (inherited from metafont) require this as a workaround.

I deduced this by a little trial and error based on some descriptions in 
the web source mp.w.

Cheers,

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 Nicola <nvitacolonna at gmail.com>
Sent: Thursday, September 15, 2016 7:44 AM
To: metapost at tug.org
Subject: [metapost] envelope

Hi,
quick question: 'envelope' is a MetaPost's spark (not documented in the
manual);
An old note of mine says that it was introduced in mpost 1.003. What is it for?
Could you make an example of how to use it?

Thanks,
Nicola


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