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Groups > comp.lang.postscript > #2708

Re: linecap rendering with zero-length lines

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On 2016-07-13, ken <ken@spamcop.net> wrote:
> Ghostscript used to draw no caps at all on zero length strokes, 
> which I see as an entirely defensible position;
> you aren't drawing the stroke, so why draw the caps.

By a strange coincidence, I yesterday ran into a use-case that
justifies that position... I've been playing with  ctransform
from chapter 8 of
  http://www.math.ubc.ca/~cass/graphics/manual/
to implement some fun transforms. One of them was a "collapse"
transform (think Black Hole, or Macular Degeneration) in which
everything within a given circle collapses down to the center, and
everything outside that circle stretches inward to fill the gap.
This means that all the points inside the circle become at zero
length from other.  I want them to vanish, to not be displayed.
I don't want them to display their caps.

> As a result Ghostscript was modified to follow the reference 
> implementation.

Hard to argue against that, though; Adobe wrote the book...

Regards,  Peter

-- 

Peter Billam    www.pjb.com.au    www.pjb.com.au/comp/contact.html

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linecap rendering with zero-length lines Alan <alan.isaac@gmail.com> - 2016-07-12 07:47 -0700
  Re: linecap rendering with zero-length lines ken <ken@spamcop.net> - 2016-07-12 17:12 +0100
    Re: linecap rendering with zero-length lines Alan <alan.isaac@gmail.com> - 2016-07-12 10:37 -0700
      Re: linecap rendering with zero-length lines Alan <alan.isaac@gmail.com> - 2016-07-12 10:58 -0700
        Re: linecap rendering with zero-length lines Markus Triska <triska@metalevel.at> - 2016-07-12 21:39 +0200
      Re: linecap rendering with zero-length lines ken <ken@spamcop.net> - 2016-07-13 07:47 +0100
        Re: linecap rendering with zero-length lines Peter Billam <peter@www.pjb.com.au> - 2016-07-20 01:09 +0000
  Re: linecap rendering with zero-length lines jdaw1 <jdawiseman@gmail.com> - 2016-07-28 03:02 -0700

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