<<>>
<<G2dSpirographCmdImpl.mesa>>
<<Copyright Ó 1985, 1992 by Xerox Corporation.  All rights reserved.>>
<<Bloomenthal, July 20, 1992 1:09 pm PDT>>
<<Glassner, May 30, 1986 12:32:04 pm PDT>>

DIRECTORY Draw2d, Commander, Controls, G2dTool, Imager, IO, Process, RealFns, Vector2, ViewerOps;

G2dSpirographCmdImpl: CEDAR PROGRAM
IMPORTS Draw2d, Controls, G2dTool, Process, RealFns, ViewerOps
~ BEGIN 

ProgramData:        TYPE ~ REF ProgramDataRep;
ProgramDataRep:    TYPE ~ RECORD [
outer:                        Controls.Viewer Ź NIL,                        -- main outer viewer
graphics:                    Controls.Viewer Ź NIL,                        -- viewer for graphics

smallAngle, bigAngle:    REAL Ź 0.0,
centerPt:                    Imager.VEC Ź [150.0, 150.0],
oldPt, newPt:                Imager.VEC,
bigAngleDelta:            REAL,
smallAngleDelta:         REAL,

smallSpeed:                 REAL Ź 37.0,            -- speed increase for the small wheel
smallR:                     REAL Ź 30.0,            -- small wheel radius
bigR:                         REAL Ź 90.0,            -- big wheel radius
modR:                     REAL Ź .4,            -- percent of small wheel radius modulation
modF:                     REAL Ź 5.0,            -- small wheel radius modulation frequency
cycles:                     REAL Ź 1.2,            -- # of small wheel rotations around the big one
numSteps:                 INTEGER Ź 5000,    -- # of steps to take once around the big wheel
loops:                     INTEGER Ź 5,        -- # of times to go around the big wheel

bigPt:                        Imager.VEC,
tmpR:                        REAL,
smallPt:                    Imager.VEC,

dset:                         INTEGER Ź 2,        -- which prebuilt data set to use
start:                        BOOL Ź TRUE,
newViewer:                BOOL Ź TRUE
];

G2dSpirograph: Commander.CommandProc ~ {
p: ProgramData Ź NEW[ProgramDataRep];
p.outer Ź Controls.OuterViewer[
name: "Spirograph",
graphicsHeight: 300,
drawProc: DrawProc,
clientData: p].parent;
p.graphics Ź NARROW[p.outer.data, Controls.OuterData].graphics;
SELECT p.dset FROM
4 => {
p.smallSpeed Ź 15.0;  p.smallR Ź 30.0;  p.bigR Ź 50.0;  p.modR Ź 1.4;  p.modF Ź 7.0;
p.cycles Ź 1.4;  p.numSteps Ź 5000;  p.loops Ź 5;
};
3 => {
p.smallSpeed Ź 15.0;  p.smallR Ź 30.0;  p.bigR Ź 90.0;  p.modR Ź .4;  p.modF Ź 7.0;
p.cycles Ź 1.4;  p.numSteps Ź 5000;  p.loops Ź 5;
};
2 => {
p.smallSpeed Ź 37.0;  p.smallR Ź 30.0;  p.bigR Ź 90.0;  p.modR Ź .4;  p.modF Ź 5.0;
p.cycles Ź 1.2;  p.numSteps Ź 5000;  p.loops Ź 5;
};
ENDCASE => {
p.smallSpeed Ź 13.0;  p.smallR Ź 30.0;  p.bigR Ź 90.0;  p.modR Ź .4;  p.modF Ź 5.0;
p.cycles Ź 1.0;  p.numSteps Ź 5000;  p.loops Ź 1;
};
p.bigAngleDelta Ź (2.0*3.1415926535*p.cycles)/p.numSteps;
p.smallAngleDelta Ź (2.0*3.1415926535*p.smallSpeed)/p.numSteps;
Process.Pause[Process.MsecToTicks[100]];
FOR n: NAT IN [0..p.loops) DO
ViewerOps.PaintViewer[p.graphics, client, FALSE, p.graphics];
Process.CheckForAbort[];
ENDLOOP;
};

DrawProc: Controls.DrawProc ~ {
p: ProgramData Ź NARROW[clientData];
IF p.newViewer THEN {
p.newViewer Ź FALSE;
Draw2d.Clear[context];
RETURN;
};
FOR n: NAT IN [0..p.numSteps) DO
p.bigPt Ź [p.bigR*RealFns.Cos[p.bigAngle], p.bigR*RealFns.Sin[p.bigAngle]];
p.tmpR Ź p.smallR + ((p.smallR * p.modR) * RealFns.Sin[p.bigAngle * p.modF]);
p.smallPt Ź [p.tmpR*RealFns.Cos[p.smallAngle], p.tmpR*RealFns.Sin[p.smallAngle]];
p.newPt.x Ź p.centerPt.x + p.bigPt.x + p.smallPt.x;
p.newPt.y Ź p.centerPt.y + p.bigPt.y + p.smallPt.y;
IF p.start
THEN p.start Ź FALSE
ELSE Draw2d.Line[context, p.oldPt, p.newPt]; 
p.oldPt Ź p.newPt;
p.bigAngle Ź p.bigAngle + p.bigAngleDelta;
p.smallAngle Ź p.smallAngle + p.smallAngleDelta;
ENDLOOP;
};

G2dTool.Register["Spirograph", G2dSpirograph, "\nDraw a spirograph."];

END.