Re: shfil

From	"luser.droog" <luser.droog@gmail.com>
Newsgroups	comp.lang.postscript
Subject	Re: shfil
Date	2012-11-16 18:29 -0600
Organization	unorganized
Message-ID	<k86lot$erj$1@dont-email.me> (permalink)
References	<87vcdcl9dg.fsf@Compaq.site.inet>

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Cecil Westerhof wrote:

> I found the shfill command with I can create gradients. Is there a good
> resource to get started? I could not find something that explains and show
> the things in layman's terms.
> 

There's some information about shading in Bill Casselman's Mathematical
Illustrations, ch. 14. He talks about Type 4 (free-form Gouraud) and Type 6
(Coons patch meshes).

The function is often implicit for the Type. The behavior is entirely
determined by the parameters and the data. Otherwise you could do it the
old way by "Riemannian" approximation: iterated over itty-bitty rectangles
and calculate the color for each one. But that tends to mess up
your "device-independence" depending on the grain of the approximation (the
dx and dy).

Interpolation is Calculus.

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Thread

shfil Cecil Westerhof <Cecil@decebal.nl> - 2012-11-11 11:30 +0100
  Re: shfil "abeddie@hotmail.com" <abeddie@hotmail.com> - 2012-11-13 07:50 -0800
    Re: shfil Cecil Westerhof <Cecil@decebal.nl> - 2012-11-13 17:56 +0100
      Re: shfil "abeddie@hotmail.com" <abeddie@hotmail.com> - 2012-11-13 10:12 -0800
        Re: shfil Cecil Westerhof <Cecil@decebal.nl> - 2012-11-13 20:10 +0100
      Re: shfil Ross Presser <rpresser@gmail.com> - 2012-11-13 11:05 -0800
        Re: shfil Herbert Voss <Herbert.Voss@alumni.tu-berlin.de> - 2012-11-13 21:24 +0100
          Re: shfil Ross Presser <rpresser@gmail.com> - 2012-11-13 21:43 -0800
  Re: shfil John Deubert <john@acumentraining.com> - 2012-11-15 09:28 -0800
  Re: shfil "luser.droog" <luser.droog@gmail.com> - 2012-11-16 18:29 -0600

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