%!
% Copyright (C) 1988 by Bruce Schwartz and Mark Lentczner. All rights
% reserved.  This program is provided for unrestricted use, provided that
% this copyright message is preserved. There is no warranty, and no
% author or distributer accepts responsibility for any damage caused by
% this program.
% 
% This is an interactive screen saver program. 
%
% The algorithms used in this program are based on an idea of Dan Ingalls.
%

/boxHeight 75 def
/boxWidth  75 def

/bs { [boxWidth boxHeight] {mul} arrayop } def

/pt1 [ .2 .2 ] bs def
/pt2 [ .3 .6 ] bs def
/pt3 [ .6 .8 ] bs def
/pt4 [ .8 .6 ] bs def

/pts [ pt1 pt2 pt3 pt4 ] def

/ptl [ .5  0 ] bs def

/dotSize boxWidth boxHeight min 24 div 2 max def
/curveWidth 1 def
/labelFont /Times-Roman findfont 20 scalefont def

/coordinates	% pt -> x y
{
	aload pop
} def


/string2Index	% s -> a b c d convert a string to the four indicies
{
	0 1 3
	{
		1 index exch 1 getinterval cvi exch
	} for
	pop
} def


/dot {
	coordinates dotSize 0 360 arc fill
} def

/paintPoints	% - -> - show the points
{
	pt1 dot
	pt2 dot
	pt3 dot
	pt4 dot
} def


/drawCurve		% a b c d -> - draw the curve in the order given
{ 10 dict begin
	1 sub /d exch def
	1 sub /c exch def
	1 sub /b exch def
	1 sub /a exch def

	curveWidth setlinewidth

	pts a get coordinates moveto
	pts b get coordinates
	pts c get coordinates
	pts d get coordinates curveto
	stroke
end } def


/labelCurve		% s -> - label a curve
{
	labelFont setfont
	ptl coordinates moveto
	cshow
} def


/locateCurve	% a b c d -> a b c d translate the world for the given spot
{ 10 dict begin
	0 index 1 sub /v exch def
	3 index 1 sub /h exch def
	h boxWidth mul 
	v boxHeight mul
	translate
end } def


/doCurve		% s -> - do it all!
{
	gsave
	dup string2Index
	% locateCurve
	paintPoints
	drawCurve
	labelCurve
	grestore
} def


/doAllCurves	% - -> - paint all 24 curves
{
	  (1234) doCurve
	  (1243) doCurve
	  (1342) doCurve

	  (2341) doCurve
	  (2134) doCurve
	  (2143) doCurve

	  (3124) doCurve
	  (3142) doCurve
	  (3241) doCurve

	  (4123) doCurve
	  (4132) doCurve
	  (4231) doCurve
} def

/curveMenuItem  % s keyword -> -
{
	/paint eq
		{currentpoint translate doCurve}
		{pop boxHeight boxWidth}
	ifelse
} def


/doHysterisisMenuItem	% - -> -
{
	userdict begin
	/hysterisis currentkey cvi def
	initState
	end
} def

/doLineMenuItem	% - -> -
{
	userdict begin
	/drawNextThing { drawNextLine } def
	initState
	end
} def

/doCurveMenuItem	% - -> -
{
	userdict begin
	/drawNextThing { drawNextCurve } def
	/CurveType currentkey 0 get def
	initState
	end
} def

/doAboutMenuItem % -> -
{
	currentcursorlocation
	[
		( Created by Mark Lentczner and Bruce Schwartz.)
		( Based on an idea by Dan Ingalls.)
	] popmsg
	
} def


/nullMenuItem	% keyword -> -
{
	/paint ne
		{boxHeight boxWidth}
	if
} def

/doNullMenuItem		% - -> -
{
} def


/hysterisismenu
	[ (5) (10) (20) (30) (40) (50) ]
	[ { doHysterisisMenuItem} ]
/new DefaultMenu send def

/curvemenu [
	 [ (1234) {curveMenuItem} ] { doCurveMenuItem }
	 [ (1243) {curveMenuItem} ] { doCurveMenuItem }
	 [ (1342) {curveMenuItem} ] { doCurveMenuItem }
	 { nullMenuItem } 			{ doNullMenuItem }

	 [ (2134) {curveMenuItem} ] { doCurveMenuItem }
	 [ (2143) {curveMenuItem} ] { doCurveMenuItem }
	 { nullMenuItem } 			{ doNullMenuItem }
	 [ (2341) {curveMenuItem} ] { doCurveMenuItem }

	 [ (3124) {curveMenuItem} ] { doCurveMenuItem }
	 { nullMenuItem } 			{ doNullMenuItem }
	 [ (3142) {curveMenuItem} ] { doCurveMenuItem }
	 [ (3241) {curveMenuItem} ] { doCurveMenuItem }

	 { nullMenuItem } 			{ doNullMenuItem }
	 [ (4123) {curveMenuItem} ] { doCurveMenuItem }
	 [ (4132) {curveMenuItem} ] { doCurveMenuItem }
	 [ (4231) {curveMenuItem} ] { doCurveMenuItem }
] /new DefaultMenu send def

{
	/LayoutStyle [4 4] def
	/StrokeSelection? true def
	/CellHorzGap 5 def
	/CellVertGap 5 def
	% /RetainCanvas? true def
} curvemenu send

/lockmenu [
	(About...)		{ doAboutMenuItem }
	(Lines)			{ doLineMenuItem }
	(Curves ->)		curvemenu
	(History ->)	hysterisismenu
] /new DefaultMenu send def