[metapost] Re: pdf output and extensions

[Larry Siebenmann]

Hi Taco,

I am still guessing wildly concerning the envelope proposal
4.  I asked,

 > what is this
 > 
 >  envelope <big Omega shaped path> withpen <medium sized circular pen>;

It seems now that the answer is ERROR. Indeed, you explained:

 > We are not talking about any new
 > functionality here, other than allowing access to the internal
 > envelope structure that is already there in current MetaPost.

But for circular (and elliptic) pens I would be surprised if
mp has calculated any envellope of any sort.  Hobby writes:

<< tracingspecs shows the outlines generated
   when drawing with a POLYGONAL pen. >> 
   (my capitalization)

I have read that *metafont* does secretly convert circular
pens to polygonal pens of approximately circular shape.  But
I doubt the same is done in the scalable mp world (which
polygon?!).  Prove me wrong!

I am not against the revised proposal 4, even with the
restriction to polygonal pens -- which makes it into a
shortcut to content already available by postprocessing. It
will be a convenience to a few mp activists, me included.  

But common-a-garden mp users deserve some less than essential
comforts too!

Cheers,

Laurent S.