Path: utzoo!attcan!uunet!cs.utexas.edu!chinacat!woody
From: woody@chinacat.Unicom.COM (Woody Baker @ Eagle Signal)
Newsgroups: comp.lang.postscript
Subject: Re: characters in perspective
Summary: pixelineremapping
Message-ID: <1625@chinacat.Unicom.COM>
Date: 11 Oct 90 04:39:34 GMT
References: <1990Oct5.155219.442@morrow.stanford.edu> <1610@chinacat.Unicom.COM> <21116@well.sf.ca.us>
Organization: a guest of Unicom Systems Development, Austin
Lines: 65

In article <21116@well.sf.ca.us>, shiva@well.sf.ca.us (Kenneth Porter) writes:
> 
> 
> I've also seen Don use a trick in which he replots an image
> with a one-pixel clipping path.  He iterates the clip over the
>  
> Woody, do you remember what Don calls this hack?
>  
Pixel line remapping.
Here is a hastily typed in example from one of Don's laserwriter corners

%
% hastily typed in from Don Lancaster's Laserwriter Secrets Corner
% #21
%

/pixellineremap
	{
	0 1 pixelprocheight 300 mul 72 div cvi
		{
		/scanlinenumber exch def
		save /snap1 exch def
		mappingproc newpath 0 scanlinenumber 72 mul 300 div moveto
		pixelprocwidth 0 rlineto 0 72 300 div rlineto
		pixelprocwidth neg 0 rlineto closepath clip newpath
		pixelproc clear snap 1 restore
		}for
	}def	

%
% mapping function changes for each application.
% this one does perspective sort of "star wars" logo
%

/mappingproc
	{
	pixelprocwidth 2 div 0 translate tiltfactor
	pixelprocheight mul dup scanlinenumber add div
	dup scale pixelprocwidth 2 div neg 0 translate
	} def

%
% demo...remove before use
%

/Helvetica-Bold findfont [40 0 0 40 0 0] makefont setfont

/pixelproc
	{
	5 5 moveto 0 134 rlineto 222 0 rlineto 0 -134 rlineto
	closepath stroke
	20 15 moveto (FREE FONT) show 20 57 moveto
	(FREE FONT) show
	20 99 moveto (FREE FONT) show
	} def

/pixelprocheight 140 def
/pixelprocwidth 230 def
/tiltfactor 8 def	% the smaller the flatter
100 200 translate pixellineremap
showpage

I hope there are no typo's
Cheers
Woody