Re: Rainbow printing

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From	John Deubert <john@acumentraining.com>
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Date	Tue, 16 Jul 2013 16:34:45 -0700
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On 2013-07-15 15:40:24 +0000, Cecil Westerhof said:

> I would like to print things with a rainbow stripe. So the top would
> be red, the bottom would be violet and the other colours would be in
> between. Is it possible to do this?

I'd be inclined to do this with a level 1 technique, using sethsbcolor:

% ========== cut here =============

/center { 300 400 } def

/innerRadius 100 def
/outerRadius 150 def

/innerColor .8 def	% Purple, close enough
/outerColor 0 def	% red

/steps 100 def

/deltaR outerRadius innerRadius sub steps div def
/deltaColor outerColor innerColor sub steps div def


/color innerColor def
deltaR setlinewidth

innerRadius deltaR outerRadius
{
	center 3 -1 roll 0 180 arc
	color 1 1 sethsbcolor
	stroke
	/color color deltaColor add def
} for

showpage

% ========== cut here =============

Not technically as smooth (or nearly as cool) as using smooth shading, 
but gets the job done.

- John


-- 
========
John Deubert
Acumen Training
PostScript & PDF Engineering Classes & Consulting
www.acumentraining.com

Learn PostScript programming techniques
Read the free Acumen Journal
acumentraining.com/acumenjournal.html

Thread

Rainbow printing Cecil Westerhof <Cecil@decebal.nl> - 2013-07-15 17:40 +0200
  Re: Rainbow printing abeddie <abeddie@hotmail.com> - 2013-07-15 09:54 -0700
    Re: Rainbow printing Cecil Westerhof <Cecil@decebal.nl> - 2013-07-15 20:56 +0200
      Re: Rainbow printing Mark Carroll <mtbc@bcs.org> - 2013-07-15 20:19 +0100
        Re: Rainbow printing Cecil Westerhof <Cecil@decebal.nl> - 2013-07-16 01:48 +0200
          Re: Rainbow printing Cecil Westerhof <Cecil@decebal.nl> - 2013-07-17 11:36 +0200
  Re: Rainbow printing Helge Blischke <h.blischke@acm.org> - 2013-07-15 18:56 +0200
  Re: Rainbow printing Michael Unger <spam.to.unger@spamgourmet.com> - 2013-07-15 19:06 +0200
    Re: Rainbow printing Michael Unger <spam.to.unger@spamgourmet.com> - 2013-07-15 22:07 +0200
  Re: Rainbow printing John Deubert <john@acumentraining.com> - 2013-07-16 16:34 -0700
    Re: Rainbow printing Cecil Westerhof <Cecil@decebal.nl> - 2013-07-17 09:10 +0200
  Re: Rainbow printing sjprouty3765@gmail.com - 2013-07-17 15:08 -0700
    Re: Rainbow printing Cecil Westerhof <Cecil@decebal.nl> - 2013-07-18 05:22 +0200
  Re: Rainbow printing luser- -droog <mijoryx@yahoo.com> - 2013-07-17 15:22 -0700
    Re: Rainbow printing luser- -droog <mijoryx@yahoo.com> - 2013-07-17 16:55 -0700
    Re: Rainbow printing Cecil Westerhof <Cecil@decebal.nl> - 2013-07-18 05:22 +0200

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