/*
 */

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

public class chpt01 extends Applet implements Runnable
{
	private Thread	 m_chpt01 = null;

	private double m_mu;
	private double m_dmu;

	double ua=0.5d;double ub=0.5d;

	double t=0.05d;double gl=9.8d;
	int wa=50; int ha=25; double va=0; double aa=0;
	int wb=200;int hb=30; double vb=0; double ab=0;
	double fa=0;double fb=0;double ma;double mb;
	double xa=60;    double ya=150;
	double xb=xa - 50;double yb=ya + ha;
	double vya = 0;//速度のy成分
	int xl=(int)Math.round(xa) + wa;
	int yl=(int)Math.round(ya) + (ha / 2);int wl=150;
	Graphics m_OffGC;Image m_OffScreen;
	int mox=377;int moy=300;
	int xarrow;//摩擦力の描画で使用

    public void init()
    {
        super.init();
        //{{INIT_CONTROLS
        setLayout(null);
        resize(500,300);
        b_init=new Button("初期化");
        add(b_init);
        b_init.reshape(378,7,91,30);
        s_mu=  new Scrollbar(Scrollbar.HORIZONTAL,(int)(0.7*100),5,0,100);
        add(s_mu);
        s_mu.reshape(378,45,84,15);
        s_dmu= new Scrollbar(Scrollbar.HORIZONTAL,(int)(0.5*100),5,0,100);
        add(s_dmu);
        s_dmu.reshape(378,67,84,15);
        s_ma= new Scrollbar(Scrollbar.HORIZONTAL,(int)(2*10),5,0,100);
        add(s_ma);
        s_ma.reshape(378,89,84,15);
        s_mb= new Scrollbar(Scrollbar.HORIZONTAL,(int)(5*10),5,0,100);
        add(s_mb);
        s_mb.reshape(378,111,84,15);
        //}}
    	//オフスクリーンを作る
		try
		{
//          m_OffScreen = createImage(size().width,size().height);
            m_OffScreen = createImage(mox,moy);
		}
		catch(Exception e)
		{
		}
		if (m_OffScreen != null)
		{
			m_OffGC = m_OffScreen.getGraphics();
		}
    }

    public boolean handleEvent(Event event)
    {
        if ((event.id == Event.SCROLL_ABSOLUTE  && event.target == s_mu)
           |(event.id == Event.SCROLL_PAGE_DOWN && event.target == s_mu)
           |(event.id == Event.SCROLL_PAGE_UP   && event.target == s_mu)
           |(event.id == Event.SCROLL_LINE_DOWN && event.target == s_mu)
           |(event.id == Event.SCROLL_LINE_UP   && event.target == s_mu)) {
                scrollAbsoluteSMu(event);
                return true;
        }
        else
        if ((event.id == Event.SCROLL_ABSOLUTE  && event.target == s_dmu)
           |(event.id == Event.SCROLL_PAGE_DOWN && event.target == s_dmu)
           |(event.id == Event.SCROLL_PAGE_UP   && event.target == s_dmu)
           |(event.id == Event.SCROLL_LINE_DOWN && event.target == s_dmu)
           |(event.id == Event.SCROLL_LINE_UP   && event.target == s_dmu)) {
                scrollAbsoluteSDmu(event);
                return true;
        }
        else
        if ((event.id == Event.SCROLL_ABSOLUTE  && event.target == s_ma)
           |(event.id == Event.SCROLL_PAGE_DOWN && event.target == s_ma)
           |(event.id == Event.SCROLL_PAGE_UP   && event.target == s_ma)
           |(event.id == Event.SCROLL_LINE_DOWN && event.target == s_ma)
           |(event.id == Event.SCROLL_LINE_UP   && event.target == s_ma)) {
                scrollAbsoluteSMa(event);
                return true;
        }
        else
        if ((event.id == Event.SCROLL_ABSOLUTE  && event.target == s_mb)
           |(event.id == Event.SCROLL_PAGE_DOWN && event.target == s_mb)
           |(event.id == Event.SCROLL_PAGE_UP   && event.target == s_mb)
           |(event.id == Event.SCROLL_LINE_DOWN && event.target == s_mb)
           |(event.id == Event.SCROLL_LINE_UP   && event.target == s_mb)) {
                scrollAbsoluteSMb(event);
                return true;
        }
        else
        if (event.id == Event.ACTION_EVENT && event.target == b_init) {
                clickedBInit();
                return true;
        }
        repaint();
        return super.handleEvent(event);
    }

    //{{DECLARE_CONTROLS
    Button b_init;
    Scrollbar s_mu;
    Scrollbar s_dmu;
    Scrollbar s_ma;
    Scrollbar s_mb;
    //}}

   	public void paint(Graphics g)
	{
		if (m_OffGC != null)
		{
			m_OffGC.setColor(getBackground());
//			m_OffGC.fillRect(0,0,size().width,size().height);
			m_OffGC.fillRect(0,0,mox,moy);
			m_OffGC.setColor(Color.black);
			m_OffGC.setFont(new Font("DIALOG",Font.PLAIN,16));
			m_OffGC.drawString("運動方程式(台の上の物体と摩擦)", 10, 20);
			drawBox(m_OffGC);
			g.drawImage(m_OffScreen,0,0,this);
		}
	}

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

	public void start()
	{
	    m_mu=s_mu.getValue()/100d;
	    m_dmu=s_dmu.getValue()/100d;
	    ma=s_ma.getValue()/10d;
	    mb=s_mb.getValue()/10d;
		if (m_chpt01 == null)
		{
			m_chpt01 = new Thread(this);
			m_chpt01.start();
		}
	}

	public void stop()
	{
		if (m_chpt01 != null)
		{
			m_chpt01.stop();
			m_chpt01 = null;
		}
	}

	public void run()
	{
		while (true)
		{
			try
			{
				repaint();
				Thread.sleep(Math.round(t * 1000));
			}
			catch (InterruptedException e)
			{
				stop();
			}
		}
	}

	public boolean mouseDrag(Event evt, int x, int y)
	{
		int wwl=10;
		if ((x>xl+wl)&&(y>yl-wwl)&&(y<yl+wwl))
		{
			fa=(x-xl-wl)/t/10;
		}
		if (fa <= m_mu * ma * gl * (mb + ma) / mb) //すべらない条件
		{
			aa=fa/(ma+mb);ab=aa;
		}
		else //すべる時
		{
			aa=fa/ma-m_dmu*gl;ab=m_dmu*ma/mb*gl;
		}
		fb = mb * ab;
		return true;
	}


	public boolean mouseMove(Event evt, int x, int y)
	{
//		aa=0;ab=0;fa=0;fb=0;
        fa=0; //引くのをやめた（他の量は適切な位置で再計算）
        
		return true;
	}
	public void p_init()
	{ //変数の初期化
    	va=0;aa=0;vb=0;ab=0;fa=0;fb=0;
	    xa=60;ya=150;
	    xb=xa - 50;yb=ya + ha;
	    xl=(int)Math.round(xa) + wa;
	    yl=(int)Math.round(ya) + (ha / 2);
	}
	public void clickedBInit()
	{
        p_init();
	}
	public void scrollAbsoluteSMu(Event ev)
	{
	    m_mu=s_mu.getValue()/100d;
	    if (m_dmu>m_mu)
	    {
	        m_dmu=m_mu;s_dmu.setValue((int)(m_dmu*100));
	    }
        p_init();
	}
	public void scrollAbsoluteSDmu(Event ev)
	{
	    m_dmu=s_dmu.getValue()/100d;
	    if (m_dmu>m_mu)
	    {
	        m_dmu=m_mu;s_dmu.setValue((int)(m_dmu*100));
	    }
        p_init();
	}
	public void scrollAbsoluteSMa(Event ev)
	{
	    ma=s_ma.getValue()/10d;
        p_init();
	}
	public void scrollAbsoluteSMb(Event ev)
	{
	    mb=s_mb.getValue()/10d;
        p_init();
	}

	private void drawArrow(Graphics g,int x1,int y1,int a,int b)
	{
		if(!((a==0)&&(b==0))){
			int x2=x1+a;int y2=y1+b;int m=6;double dd=0.6d;
			g.drawLine(x1,y1,x2,y2);
			double d=Math.atan2((double)b,(double)a);
			double xa=x2-m*Math.cos(d+dd);
			double ya=y2-m*Math.sin(d+dd);
			g.drawLine(x2,y2,(int)xa,(int)ya);
			double xb=x2-m*Math.cos(d-dd);
			double yb=y2-m*Math.sin(d-dd);
			g.drawLine(x2,y2,(int)xb,(int)yb);
		}
	}

	private void drawBox(Graphics g)
	{
		if (fa==0){ //引く力が０のときはmouseDrag()で処理していない
		  if (va>vb){ //ずれている間は摩擦がはたらくので加速する
		    aa = (-m_dmu * gl);
			ab = m_dmu * ma * gl / mb;
          }
          else{
		    aa = 0;
		    ab = 0;
		    va = vb; //念のため
          }
          fb = mb * ab; //摩擦力の大きさを計算
        }
		//位置計算
		va+=aa*t;vb+=ab*t;
		xa+=va*t;xb+=vb*t;
		if(xa > xb + wb){ //台から外れた
		    aa = fa / ma; //上の物体は加速
		    ab = 0; //下の物体は加速せず（外力０）
		    fb = 0; //摩擦もない
		    if(ya < yb + hb - ha){ //床につく前
		        vya += gl * t;
        		ya += vya * t;
        	}
		    else{ //床に落ちた
		        ya = yb + hb - ha;
		    }
		    yl=(int)Math.round(ya) + (ha / 2); //ひも
		}
		xl=(int)Math.round(xa) + wa; //ひも
		//描画
		g.setColor(Color.black);
		g.drawLine(0,(int)yb+hb,mox,(int)yb+hb);//床
		g.drawRect((int)xa,(int)ya,wa,ha);//上の箱
		g.drawRect((int)xb,(int)yb,wb,hb);//下の箱
		g.drawLine(xl,yl,xl+wl,yl);//ひも
		g.setColor(Color.red);
		drawArrow(g,xl,yl,(int)fa,0);
		xarrow = (int)((xa + wa/2 < xb + wb) ? xa + wa/2 : xb + wb); //摩擦力の位置をそれらしく
		drawArrow(g,xarrow,(int)ya+ha,(int)-fb,0);
		g.setColor(Color.blue);
		drawArrow(g,xarrow,(int)ya+ha,(int)fb,0);
//		drawArrow(g,(int)xa+wa/2,(int)yb,(int)fb,0);
		g.setColor(Color.black);
		g.drawString("静止摩擦係数 "+m_mu ,240,58);
		g.drawString("動摩擦係数　 "+m_dmu,240,80);
		g.drawString("上の物体の質量 "+ma+"[kg]" ,210,102);
		g.drawString("下の物体の質量 "+mb+"[kg]" ,210,124);
	}
}