//
//	Buffon(ビュフォンの針)    2001/11/03    by ONOZATO Takehisa
//
//	<applet code="Buffon.class" width=440 height=360></applet>
//

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

public class Buffon extends Applet implements ActionListener{

	Image ofs; Graphics grf;			//オフスクリーン
	int ofsWidth=440; int ofsHeight=360;
	Color ofsBG=new Color(255,239,223);		//背景色
	Font fnt; String fname; int fstyle;		//フォント

	int originX=60; int originY=280;		//原点
	int unit=40;					//単位当たりのピクセル数
	int needle; int needleSum;			//投げた本数
	int count; int countSum;			//平行線にかかった本数

	Button btn1,btn2;				//ボタン
	boolean flg;				//false:クリア　true:試行結果表示

    public void init(){

	ofs=createImage(ofsWidth,ofsHeight); grf=ofs.getGraphics();
	fnt=grf.getFont();				//フォント
	fname=fnt.getName(); fstyle=fnt.getStyle();
	grf.setFont(new Font(fname,fstyle,16));		//16pt

	btn1=new Button("Trial"); btn1.addActionListener(this); add(btn1);
	btn2=new Button("Clear"); btn2.addActionListener(this); add(btn2);
	flg=false;

	needle=0; needleSum=0; count=0; countSum=0;
    }

    public void update(Graphics g) {
	paint(g);
    }
    
    public void paint(Graphics g){

	grf.setColor(ofsBG);
	grf.fillRect(0,0,ofsWidth,ofsHeight);		//背景

	btn1.setBounds(340,40,50,25);			//ボタンの配置
	btn2.setBounds(340,70,50,25);

	grf.setColor(Color.gray);
	for(double x=0; x<6; x=x+1){
	    grf.drawLine(picX(x),picY(-1),picX(x),picY(6));	//平行線
	}
	if(flg){
	    drawNeedle();
	}
	g.drawImage(ofs,0,0,this);	//オフスクリーンからアプレットへ描画
    }

/*** ボタンのイベント ***/
    public void actionPerformed(ActionEvent e){
	if(e.getActionCommand()=="Clear"){
	    flg=false;
	    needle=0; needleSum=0; count=0; countSum=0;	    
	}else{
	    flg=true;
	}
	repaint();
    }

/*** 試行結果の表示 ***/
    void drawNeedle(){

	needle=100; needleSum=needleSum+100; count=0;

	for(int i=1; i<=100; i++){
	    double x1=5*Math.random();
	    double y1=5*Math.random();
	    double theta=2*Math.PI*Math.random();
	    double x2=x1+Math.cos(theta);
	    double y2=y1+Math.sin(theta);
	    int hit=Math.abs((int)(x1+1)-(int)(x2+1));
	    if(hit==1){
		count=count+1;
		grf.setColor(Color.red);
	    }else{
		grf.setColor(Color.blue);
	    }
	    grf.drawLine(picX(x1),picY(y1),picX(x2),picY(y2));
	}
	countSum=countSum+count;

	int p1=(int)(20000*((double)needle/(double)count));
	int p2=(int)(20000*((double)needleSum/(double)countSum));
	double p=(double)p1/10000;
	double q=(double)p2/10000;
	grf.setColor(Color.black);
	grf.drawString("N = "+needle,310,140);
	grf.drawString("n = "+count,310,165);
	grf.drawString("2(N/n) = "+p,310,190);
	grf.drawString("累計",310,220);
	grf.drawString("N = "+needleSum,310,245);
	grf.drawString("n = "+countSum,310,270);
	grf.drawString("2(N/n) = "+q,310,295);
    }

/*** 座標の換算 ***/
    int picX(double x){
	int xx=originX+(int)(x*unit); return xx;
    }
    int picY(double y){
	int yy=originY-(int)(y*unit); return yy;
    }

}