import java.applet.*;import java.awt.*;import java.awt.event.*;//定義Driver類public class Driver extends Applet implements Runnable, MouseMotionListener, MouseListener{	Particle[] p;//定義一個Particle對象p	Graphics memScreen;	Image memImage;	int NUM_BOIDS = 50;	int WIDTH = 640;	int HEIGHT = 480;	long fps, frames, firstFrame;	int mx, my;	boolean mouseIn = false;	//初始化		        public void init()	{		memImage = createImage( WIDTH, HEIGHT );                memScreen = memImage.getGraphics();		//實例化對象p		p = new Particle[NUM_BOIDS];		//初始化對象p		for(int i = 0; i < NUM_BOIDS; i++)		{                        p[i] = new Particle();                        p[i].initialize(WIDTH/2, HEIGHT/2);		}		addMouseMotionListener(this);		addMouseListener(this);		Thread t = new Thread(this);		t.start();		}	//開始	public void start()        {               firstFrame=System.currentTimeMillis();               frames = 0;        }	//運行	public void run()	{		float[] v1 = new float[2];		float[] v2 = new float[2];		float[] v3 = new float[2];		float[] v4 = new float[2];		float[] v5 = new float[2];		while(true)		{			try			{				Thread.sleep(20);				for(int i = 0; i<NUM_BOIDS; i++)				{					v1 = moveto_cent_of_mass(i);					v2 = check_distance(i);					v3 = match_velocity(i);					v4 = check_bounds(i);									v5 = follow_leader(i);					p[i].update(v1, v2, v3, v4, v5, i, mouseIn);				}			}			catch(Exception e){}				repaint();		}	}	//follow_leader方法，實現跟隨領導顆粒的規則	public float[] follow_leader(int curr_boid)	{		float[] v = new float[2];			if(!mouseIn && curr_boid!=0)			{			v[0] = (p[0].x - p[curr_boid].x)/1000.0f;			v[1] = (p[0].y - p[curr_boid].y)/1000.0f;		}		else if(!mouseIn && curr_boid==0)		{			v[0] = (p[curr_boid].x - p[1].x)/1000.0f;                        v[1] = (p[curr_boid].y - p[1].y)/1000.0f;		}		if(mouseIn)		{			v[0] = (mx - p[curr_boid].x)/1000.0f;			v[1] = (my - p[curr_boid].y)/1000.0f;		}		return v;	}	//check_bounds方法，負責檢測是否到達邊界	public float[] check_bounds(int curr_boid)	{		float[] v = new float[2];		if(p[curr_boid].x < 0)			v[0] = 1.0f;		else if(p[curr_boid].x > 640)			v[0] = -1.0f;			if(p[curr_boid].y < 0)			v[1] = 1.0f;		else if(p[curr_boid].y > 480)			v[1] = -1.0f;		return v;	}	//moveto_cent_of_mass方法，實現盡量占據蜂群中心位置規則	public float[] moveto_cent_of_mass(int curr_boid)	{		float[] v = new float[2];		for(int i = 0; i < NUM_BOIDS; i++)		{			if(i!=curr_boid)			{				v[0]+=p[i].x;				v[1]+=p[i].y;			}		}				v[0]=(v[0]/(NUM_BOIDS-1));		v[1]=(v[1]/(NUM_BOIDS-1));		v[0] = (v[0] - p[curr_boid].x) / 700.0f;		v[1] = (v[1] - p[curr_boid].y) / 700.0f;		return v;			}	//check_distance方法，負責測試與其他顆粒間的距離	public float[] check_distance(int curr_boid)	{		float[] v = new float[2];		for(int i = 0; i < NUM_BOIDS; i++)                {                        if(i!=curr_boid)                        {				if(Math.abs(p[curr_boid].x - p[i].x) < 0.8f)				{	                                v[0]-=((p[curr_boid].x - p[i].x));	                        }				if(Math.abs(p[curr_boid].y - p[i].y) < 0.8f)				{				        v[1]-=((p[curr_boid].y - p[i].y));				}                        }                }		return v;	}	//match_velocity方法，實現與其他顆粒保持相同速度的規則	public float[] match_velocity(int curr_boid)	{		float[] v = new float[2];				for(int i = 0; i < NUM_BOIDS; i++)                {                        if(i!=curr_boid)                        {                                v[0]+=p[i].velocityX;                                v[1]+=p[i].velocityY;                        }                }		v[0]=((v[0]/(NUM_BOIDS-1))/700.0f);		v[1]=((v[1]/(NUM_BOIDS-1))/700.0f);				return v;	}	//update方法	public void update(Graphics gr)	{		paint(gr);	}	//paint方法，負責在屏幕上輸出運行結果	public void paint(Graphics gr)	{		memImage.flush();		memScreen.setColor(Color.black);                memScreen.fillRect(0,0,WIDTH,HEIGHT);		        memScreen.setColor(Color.green); 		for(int i = 0; i < NUM_BOIDS; i++)		{		                memScreen.fillRect((int)p[i].x, (int)p[i].y, 3, 3);			memScreen.setColor(Color.white);		}		frames++;                fps = (frames*10000) / (System.currentTimeMillis()-firstFrame);                memScreen.setColor(Color.white);                memScreen.drawString(fps/10 + "." + fps%10 + " fps", 2, HEIGHT - 2);		gr.drawImage(memImage,0,0,this);	}	//處理鼠標移動事件	public void mouseMoved(MouseEvent e)	{		mx = e.getX();		my = e.getY();	}	//處理鼠標進入事件	public void mouseEntered(MouseEvent e)	{		mouseIn = true;	}	//處理鼠標移出事件	public void mouseExited(MouseEvent e)	{		mouseIn = false;	}	//處理其他鼠標事件	public void mouseClicked(MouseEvent e){}	public void mousePressed(MouseEvent e){}	public void mouseReleased(MouseEvent e){}	public void mouseDragged(MouseEvent e)	{	}}