%!PS

% A Proposed Logo for Linux...

% ps-hack by
%   Jeff Moore (jbm@sbi.com) 13 Aug 92
%
% based on logo design by
%   James P. Callison (callison@uokmax.ecn.uoknor.edu)

% Well, I said I'd give it a shot, so here it is: an attempt to describe
% callison's logo in hand-coded PostScript.  It gets a little excessive
% in parts, especially where I thrash around with the color gradient
% fill, and of course I couldn't resist tweaking a little bit to please
% *my* eye; but the net result's a PostScript function which takes four
% arguments: xposition, yposition, logo-height and release-descriptive
% text.  By default, it's set up to just make the background triangle a
% solid color, since the gradient fill can render, um, oddly on the
% previewers I've tried; but just change `llDoGradient' from `false' to
% `true' to switch.

% Tweakables:

/llTriangleTopRGB { 0.96 0.95 1.0 } def	% These are guesses because...
/llTriangleBottomRGB { 0.4 0.3 0.75 } def% ...I'm not sure about my test...
/llBarRGB { 0.8 0.0 0.5 } def		% ...output device.

/llTextRGB { 0.0 0.0 0.0 } def		% Think I have this right.

/llFontFamily /Times-Italic findfont def

/llDoGradient false def			% Do funky shading of triangle?
/llTriangleSolidRGB { 0.8 0.7 1.0 } def	% If not, use this.
/llBarLineCap 0 def

% More tweakable relationships.  Silly hack to avoid calculating
%  constants which depend on llHeight more than once per logo call.
/llFigureDependantConstants {		% --
  /llWidth llHeight 1.17 mul def

  /llBarLineWidth llHeight 19 div def
  /llBarYDelta llHeight -0.48 mul def

  /llBigLPoints llHeight 0.63 mul def	% ...height of char < "points"...
  /llInuxPoints llBigLPoints 0.415 mul def
  /llRelTextPoints llBigLPoints 0.165 mul def
} def


/llFont {				% points --
  llFontFamily exch scalefont setfont
} def


% some rgb-triple handlers (can this be necessary?)

/rgbadd {				% r1 g1 b1 r0 g0 b0 -- rsum gsum bsum
  6 -1 roll				% -- g1 b1 r0 g0 b0 r1
  4 -1 roll				% -- g1 b1 g0 b0 r1 r0
  add					% -- g1 b1 g0 b0 rsum
  5 -1 roll				% -- b1 g0 b0 rsum g1
  4 -1 roll add				% -- b1 b0 rsum gsum
  4 2 roll add				% -- rsum gsum bsum
} def

/rgbsub {				% r1 g1 b1 r0 g0 b0 -- rsum gsum bsum
  6 -1 roll				% -- g1 b1 r0 g0 b0 r1
  4 -1 roll				% -- g1 b1 g0 b0 r1 r0
  sub					% -- g1 b1 g0 b0 rsum
  5 -1 roll				% -- b1 g0 b0 rsum g1
  4 -1 roll sub				% -- b1 b0 rsum gsum
  4 2 roll sub				% -- rsum gsum bsum
} def

/rgbdiv {				% r g b d -- r/d g/d b/d
  4 -1 roll 1 index div			% -- g b d r/d
  4 -1 roll 2 index div			% -- b d r/d g/d
  4 2 roll div				% -- r/d g/d b/d
} def

/rgbdup {				% r g b -- r g b r g b
  3 copy
} def

/rgb1index {				% rgb1 rgb0 -- rgb1 rgb0 rgb1
  6 3 roll 3 copy 9 3 roll
} def

/rgbpop {				% r g b --
  pop pop pop
} def


% subfunctions which render assume starting at UL of logo...

/llDrawTriangle {			% --
  llDoGradient {
    % Never tried this color stuff before.  This may be stupidly
    %  complicated and expensive for the job...  We're trying to
    %  tromp "linearly" through RGB color-space between the
    %  supplied endpoints.  If hue changes, this seems to cause
    %  color-banding with the previewers I've tried; and successive
    %  FP additions result in errors by end...

    % (keep some variables in lieu of stack machismo:)
    /lltYStep 0 1 idtransform exch pop def % device Y unit in user coords
    /lltXStep lltYStep neg llWidth mul llHeight div 2 div def
    /lltSliceWidth llWidth def
    lltYStep neg setlinewidth 0 setlinecap
    
    llTriangleTopRGB llTriangleBottomRGB rgbsub % rgbdelta
    llHeight lltYStep div		% rgbdelta -- rgbdelta numdivs
    rgbdiv				% rgbdelta numdivs -- rgbstep
    
    llTriangleTopRGB			% rgbstep -- rgbstep toprgb
    0 lltYStep neg llHeight {
      pop
      gsave
	rgbdup setrgbcolor		% rgbstep thisrgb
	/lltSliceWidth lltSliceWidth dup 0 rlineto stroke lltXStep dup add sub def
      grestore
      lltXStep lltYStep rmoveto
      rgb1index rgbadd			% rgbstep thisrgb -- rgbstep nextrgb
    } for
    rgbpop rgbpop
  } {
    % Just punt with a single color
    llWidth 0 rlineto
    llWidth -2 div llHeight neg rlineto
    closepath
    llTriangleSolidRGB setrgbcolor fill
  } ifelse
} def

/llDrawBar {				% --
  llBarLineCap setlinecap
  0 llBarYDelta rmoveto
  llBarRGB setrgbcolor llBarLineWidth setlinewidth
  llWidth 0 rlineto stroke
} def

/llDrawLogo {				% llx lly height reltext --

  /llReleaseText exch def		% llx lly height reltext -- llx lly height
  /llHeight exch def			% llx lly height -- llx lly
  moveto				% llx lly --

  llFigureDependantConstants

  gsave llDrawTriangle grestore
  gsave llDrawBar grestore
  
  % big fat "L"
  llWidth 0.13 mul llBarYDelta llBigLPoints 0.190 mul sub rmoveto
  llBigLPoints llFont
  llTextRGB setrgbcolor
  (L) show

  % scribble in release text
  gsave
    llRelTextPoints dup llFont
    dup -0.09 mul exch 0.1 mul rmoveto	% nestle against L; raise baseline a hair...
    llReleaseText show
  grestore
  
  % "INUX" (sorry, I like it better when it doesn't dangle outside triangle...)
  llBigLPoints -0.32 mul llBigLPoints 0.25 mul rmoveto
  llInuxPoints llFont
  (INUX) show

} def


% Do it!
100 700 190.9 (RELEASE 0.97) llDrawLogo % approx size, pos as supplied by callison
% 40 675 450 (RELEASE 0.97) llDrawLogo	% big 'un
270 250 80 (RELEASE 1.0) llDrawLogo	% A Goal

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