/**
        Program:        Pascal3
        Purpose:        Reccurence figure
        @author:        Sanae.Masasi
        @version:       1.00; 1.June.96
*/


import java.awt.*;
import java.applet.*;

public class Pascal3 extends Applet{

    Control3 controls;
    public void init(){
	setLayout(new BorderLayout());
	Canvas3 c = new Canvas3();
	add("Center",c);
	add("South",controls = new Control3(c));
	c.setBackground(Color.white);

    }

    public void start(){
	controls.enable();
    }

    public void stop(){
	controls.disable();
    }

    public boolean handleEvent(Event e){
	if(e.id == Event.WINDOW_DESTROY){
	    System.exit(0);
	}
	return false;
    }

}

class Canvas3 extends Canvas{
    
    int a = 1,b = 0,c = 1,q = 2;
    int xx,yy,cx;
    int ff[] = new int[600];
    int gg[] = new int[600];

    Rectangle rect;

    public void paint(Graphics g) {

    }

    public void update(Graphics g) {

	int xs,ys;
	rect = bounds();
	yy = (int)(rect.height / Math.sqrt(3d));
	cx = (int)(rect.width / 2);
	xx = 2 * cx;
	g.setColor(Color.white);
	g.fillRect(0,0,rect.width,rect.height);

	for(int x = 0;x < xx;x++){
	    if(x == cx){
		ff[x] = 1;
		g.setColor(Color.red);
		g.drawLine(x,0,x,0);
	    }else{
		ff[x] = 0;
	    }
	}
	for(int y = 1;y < yy;y++){
	    for(int x = 0;x < xx;x++){
		if(x == 0){
		    gg[x] = b * ff[x] + c * ff[x+1];
		}else if(x == xx - 1){
		    gg[x] = a * ff[x - 1] + b * ff[x];
		}else{
		    gg[x] = a * ff[x - 1] + b * ff[x] + c * ff[x + 1];
		}
	        gg[x] = gg[x] % q;
		if(gg[x] != 0){
		    g.setColor(Color.red);
		    xs = x;
		    ys = (int)(y * Math.sqrt(3d));
		    g.drawLine(xs,ys,xs,ys);
		}
	    }
	    for(int x = 0;x < xx;x++) ff[x] = gg[x];
    	}
    }

    public void redraw(int a,int b,int c,int q){
	this.a = a;
	this.b = b;
	this.c = c;
	this.q = q;
	repaint();
    }
}


class Control3 extends Panel{

    Canvas3 canvas;
    Font font = new Font("TimesRoman",Font.ITALIC,12);
    Choice FigA,FigB,FigC,FigQ;
    Label labelA,labelB,labelC,labelQ;
    public Control3(Canvas3 canvas){

	this.canvas = canvas;
	setLayout(new FlowLayout());

	labelA = new Label("fig a,b,c  ",Label.LEFT);
	labelA.setFont(font);
	add(labelA);
	FigA = new Choice();
	for(int i = -5;i <=5;i++){
	    FigA.addItem("" + i);
	}
	FigA.select(String.valueOf(canvas.a));
	add(FigA);

	FigB = new Choice();
	for(int i = -5;i <=5;i++){
	    FigB.addItem("" + i);
	}
	FigB.select(String.valueOf(canvas.b));
	add(FigB);

	FigC = new Choice();
	for(int i = -5;i <=5;i++){
	    FigC.addItem("" + i);
	}
	FigC.select(String.valueOf(canvas.c));
	add(FigC);

	labelQ = new Label("rest  ",Label.LEFT);
	labelQ.setFont(font);
	add(labelQ);
	FigQ = new Choice();
	for(int i = 2;i <=15;i++){
	    FigQ.addItem("" + i);
	}
	FigQ.select(String.valueOf(canvas.q));
	add(FigQ);

	add(new Button("DRAW"));

    }

    public boolean action(Event ev, Object arg) {

	if (ev.target instanceof Button) {
	    
	    canvas.redraw(Integer.parseInt(FigA.getSelectedItem()),
		Integer.parseInt(FigB.getSelectedItem()),
		Integer.parseInt(FigC.getSelectedItem()),
		Integer.parseInt(FigQ.getSelectedItem()));
	}
	return false;
    }
}