/* PatternApplet.java - draws 'spirograph' patterns */

import java.awt.*;

class OuterGear {
	//instance variables
	Dimension centre;
	int rad;
	int angle;
	
	//constructor
	public OuterGear(Dimension centre, int rad) {
		this.centre = centre;
		this.rad = rad;
		angle = 0;
	}
}

class InnerGear {
	//class variables
	static private float sines[] = new float[360]; 
	static private float cosines[] = new float[360];

	//instance variables 
	OuterGear outer;
	int rad, penrad;
	int angle;
	int numTurns, maxNumTurns;
	float ratio, radDiff;
	Color c;
	boolean donePaint = false;
	boolean firstPaint = true;
	
	//initalise class variables
	static {
		double x, dx;
		dx = 6.283 / 360;
		x = 0.0;
		for (int i=0; i<360; i++) {
			sines[i] = (float)Math.sin(x);
			cosines[i] = (float)Math.cos(x);
			x += dx;
		}
	}

	//constructor
	public InnerGear(int rad, int penrad, OuterGear outer, Color c) {
		if (rad > outer.rad) {
			System.out.println("error - inner rad > outer rad");
			System.exit(0);
		}
		if (penrad > rad) {
			System.out.println("error - pen rad > gear rad");
			System.exit(0);
		}
		this.rad = rad;
		this.penrad = penrad;
		this.outer = outer;
		this.c = c;
		ratio = (float)rad / (float)outer.rad;
		radDiff = (float)(outer.rad - rad);
		angle = 0;
		numTurns = 0;
		maxNumTurns = getMaxNumTurns();
	}

	//return number of turns required to complete the pattern
	public int getMaxNumTurns() {
		int i = 1;
		int j = 1;
		int radA, radB;
		while(true) {
			radA = i * rad;
			radB = j * outer.rad;
			if (radA == radB) break;
			if (radA > radB) {
				j++;
			} else {
				i++;
				j = 1;
			}
		}
		return i;
	}

	//work out pen position given current angle
	public Dimension getPenPos(int angle) {
		Dimension d = new Dimension();
		outer.angle = (int)((float)(angle + numTurns * 360) * ratio);
		if (outer.angle > 359) outer.angle -= (outer.angle / 360) * 360;
		d.width = outer.centre.width + (int)(radDiff * cosines[outer.angle] 
			+ (float)penrad * cosines[angle]);
		d.height = outer.centre.height + (int)(radDiff * sines[outer.angle] 
			- (float)penrad * sines[angle]);
		return d;
	}		
		
	public Dimension paintTrail(Graphics g) {
		g.setColor(c);
		Dimension oldP, newP;
		Dimension d = new Dimension();
		oldP = getPenPos(angle);
		for (int i=0; i<60; i++) {
			angle++;
			if (angle == 360) {
				angle = 0;
				numTurns++;
				if (numTurns == maxNumTurns) donePaint = true;
			}
			newP = 	getPenPos(angle);
			g.drawLine(oldP.width, oldP.height, newP.width, newP.height);
			oldP = newP;
			if (i == 30) d = oldP;
		}
		if (firstPaint) firstPaint = false;
		return d;
	}				
}

public class PatternApplet extends java.applet.Applet implements Runnable {
	//class variables
	Thread t = null;
	int index;
	int numOuts, numIns;
	int outR[];
	int xOff[];
	int yOff[];
	int inR[];
	int penR[];
	int inOut[];
	int col[];
	OuterGear outer;
	InnerGear inner;
	Image vImage;
	Graphics vg;
	Dimension centre, clipper;
	int clip;

	//initialise applet
	public void init() {
		setBackground(Color.black);
		centre = getCentre();
		getGears();
		index = 0;
	}

	public void getGears() {
		String p = getParameter("numOuts");
		numOuts = (p != null) ? Integer.valueOf(p).intValue() : 1;
		p = getParameter("numIns");
		numIns = (p != null) ? Integer.valueOf(p).intValue() : 1;
		outR = new int[numOuts];
		xOff = new int[numOuts];
		yOff = new int[numOuts];
		inR = new int[numIns];
		penR = new int[numIns];
		inOut = new int[numIns];
		col = new int[numIns];
		p = getParameter("outR0");
		outR[0] = (p != null) ? Integer.valueOf(p).intValue() : 200;
		p = getParameter("xOff0");
		xOff[0] = (p != null) ? Integer.valueOf(p).intValue() : 0;
		p = getParameter("yOff0");
		yOff[0] = (p != null) ? Integer.valueOf(p).intValue() : 0;
		p = getParameter("inR0");
		inR[0] = (p != null) ? Integer.valueOf(p).intValue() : 65;
		p = getParameter("penR0");
		penR[0] = (p != null) ? Integer.valueOf(p).intValue() : 65;
		p = getParameter("inOut0");
		inOut[0] = (p != null) ? Integer.valueOf(p).intValue() : 0;		
		p = getParameter("col0");
		col[0] = (p != null) ? Integer.valueOf(p).intValue() : 0;
		String parm;
		if (numIns > 1) {
			for (int i=0; i<numIns; i++) {
				parm = "inR" + Integer.toString(i);
				p = getParameter(parm);
				inR[i] = Integer.valueOf(p).intValue();
				parm = "penR" + Integer.toString(i);
				p = getParameter(parm);
				penR[i] = Integer.valueOf(p).intValue();
				parm = "inOut" + Integer.toString(i);
				p = getParameter(parm);
				inOut[i] = Integer.valueOf(p).intValue();
				parm = "col" + Integer.toString(i);
				p = getParameter(parm);
				col[i] = (p != null) ? Integer.valueOf(p).intValue() : 0;
			}
		}
		if (numOuts > 1) {
			for (int i=0; i<numOuts; i++) {
				parm = "outR" + Integer.toString(i);
				p = getParameter(parm);
				outR[i] = Integer.valueOf(p).intValue();
				parm = "xOff" + Integer.toString(i);
				p = getParameter(parm);
				xOff[i] = (p != null) ? Integer.valueOf(p).intValue() : 0;
				parm = "yOff" + Integer.toString(i);
				p = getParameter(parm);
				yOff[i] = (p != null) ? Integer.valueOf(p).intValue() : 0;
			}
		}
	}

	//return color given int
	Color getCol(int i) {
		switch (i) {
			case 0: return Color.white;
			case 1: return Color.red;
			case 2: return Color.yellow;
			case 3: return Color.green;
			case 4: return Color.blue;
			case 5: return Color.orange;
			case 6: return Color.cyan;
		}
		return Color.white;
	}

	Dimension getCentre() {
		Dimension d = size();
		d.width = d.width / 2;
		d.height = d.height / 2;
		return d;
	}

	public void start() {
		if (t == null) {
			t = new Thread(this);
			t.start();
		}
	}

	public void stop() {
		if (t != null) {
			t.stop();
			t = null;
		}
	}

	public void run() {
	    	vImage = createImage(size().width, size().height);
	    	vg = vImage.getGraphics();
		Thread.currentThread().setPriority(Thread.NORM_PRIORITY - 1);
		while (t != null) {
			if ((inner == null) && (outer == null)) {
				centre.width += xOff[inOut[index]];
				centre.height += yOff[inOut[index]];
				outer = new OuterGear(centre, outR[inOut[index]]);
				inner = new InnerGear(inR[index], penR[index], 
					outer, getCol(col[index]));
				clip = (int)((float)inner.rad * 1.1 
					+ (float)inner.penrad * 1.1);
				centre = getCentre();
			}
			paintNext(getGraphics());
			if (inner.donePaint) {
				if (index < numIns - 1) {
					outer = null;
					inner = null;
					index++;
				} else {
					break;
				}
			}
			try {
				Thread.sleep(0, 1);
			}
			catch (InterruptedException e) {
				break;
			}
		}
	}

	public void paintNext(Graphics g) {
		if ((inner != null) && (outer != null)) {
			clipper = inner.paintTrail(vg);	
			g.clipRect(clipper.width - clip / 2, 
				clipper.height - clip / 2, clip, clip);
		}
		if (vImage != null) g.drawImage(vImage, 0, 0, this);
		g.dispose();
	}

	public void paint(Graphics g) {
		if (vImage != null) g.drawImage(vImage, 0, 0, this);
	}

	public boolean handleEvent(Event e) {
		if (e.id == Event.WINDOW_DESTROY) {
			if (vg != null) vg.dispose();
			System.exit(0);
			return true;
		}
		return super.handleEvent(e);
	}
}