/** applet No. t04
 *
 * molecular dynamics 2D
 * Ar atom - Lennard-Jones 12-6 potential
 * - multi thread  MD2D :: display - asynchronous
 *
 * Created by Ikeuchi Mitsuru on July 28 2007.
 * Copyright (c) 2007-2008 Ikeuchi Mitsuru. All rights reserved.
 *
 * ver 0.0.1   2007.07.28  created
 * ver 0.0.2   2008.06.21  added setGUIPannel()
 *
 */

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

public class multiThreadMD2D extends Applet
	implements ItemListener, ActionListener, AdjustmentListener, Runnable {

	// ------------------------------------ preset field -----------

	Thread th = null; // for run()-paint() thread
	Thread th_md = null; // for MD2D() thread
	MD2D md = new MD2D();

	// for event
	private Choice ch_tempCont, ch_view;
	private Button bt_reset, bt_startStop, bt_step;
	private Scrollbar sc_temp;

	// for off-paint buffer
	private Dimension dim;
	private Image imgOff;
	private Graphics gOff;

	// display
	private int sleepTime = 30; // sleep time (ms)
	private int dispWidth = 630;
	private int dispHeight = 460;
	private int dispMode = 0;
	private double boxDispWidth = 320.0;
	private double viewScale = 1.0;


	// ------------------------------ applet main thread -----------

	public void init() {

		resize(dispWidth,dispHeight);
		setBackground(Color.white);

		dim = getSize();
		imgOff = createImage(dim.width,dim.height);
		gOff = imgOff.getGraphics();

		setGUIPannel();
	}

	public void start() {
		if (th == null) {
			th = new Thread(this);
			th.start();
		}
		if (th_md == null) {
			th_md = new Thread(md);
			th_md.start();
		}
	}

	public void stop() {
		if (th != null) th = null;
		if (th_md != null) th_md = null;
	}




	// ===================================== GUI control ===========

	private void setGUIPannel() {

		setChoice();
		setButton();
		setScrollbar();

		setLayout(new BorderLayout());
		Panel pnl = new Panel();
		pnl.setLayout(new GridLayout(1,6,5,0));
		// pnl.add(new Label("  "));
		pnl.add(bt_reset);
		pnl.add(bt_startStop);
		pnl.add(new Label("  "));
		pnl.add(ch_tempCont);
		pnl.add(sc_temp);
		pnl.add(ch_view);
		add(pnl,"North");
	}


	// choice
	private void setChoice() {
		ch_tempCont = new Choice();
		ch_tempCont.add("adiabatic");
		ch_tempCont.add("T scaling"); 
		ch_tempCont.add("wall cont.");
		ch_tempCont.addItemListener(this);
		ch_tempCont.select("wall cont."); 

		ch_view = new Choice();
		ch_view.add("ball");
		ch_view.add("line");
		ch_view.add("velocity");
		ch_view.addItemListener(this);
		ch_view.select("ball");
	}

	public void itemStateChanged(ItemEvent ev){
		if (ev.getSource() == ch_tempCont) {
			md.setTempMode( ch_tempCont.getSelectedIndex() );
		} else if (ev.getSource() == ch_view) {
			dispMode = ch_view.getSelectedIndex();
		}
	}


	// button
	private void setButton() {
		bt_reset = new Button("reset");
		bt_reset.addActionListener(this);

		bt_startStop = new Button("start/stop");
		bt_startStop.addActionListener(this); 

		bt_step = new Button("step");
		bt_step.addActionListener(this);
	}

	public void actionPerformed(ActionEvent ev){
		if (ev.getSource() == bt_reset){ 
			md.reset();
		} else if (ev.getSource() == bt_startStop){
			if (md.getStartSW()==0) {
				md.setStartSW(1);
			} else {
				md.setStartSW(0);
			}
		} else if (ev.getSource() == bt_step){
			if (md.getStartSW()==0) {
				md.setStepSW();
			}
		}
	}


	// scrollbar
	private void setScrollbar() {
		sc_temp = new Scrollbar(Scrollbar.HORIZONTAL,300,10,10,610);
		sc_temp.addAdjustmentListener(this);
	}

	public void adjustmentValueChanged(AdjustmentEvent ev){
		if (ev.getSource() == sc_temp) { 
			md.setContTemp( 1.0*(double)(sc_temp.getValue()) );
		}
	}




	// ========================= run() - paint() loop ==============

	public void run() {
		while (th != null) {
			offPaint();
			repaint();
			try {
				Thread.sleep(sleepTime);
			} catch (InterruptedException e) { }
		}
	}

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

	public void paint(Graphics g) {
		g.drawImage(imgOff,0,0,this);
	}


	// --------------------------------------- off-paint -----------

	private void offPaint() {
		int gbx,gby;
		double dispScale,sc;

		if (md==null) return;
		dispScale = (boxDispWidth/md.getXMax());

		gOff.setColor(Color.white);
		gOff.fillRect(0,0,dim.width,dim.height);

		gbx = 30;
		gby = 90;
		sc = viewScale*dispScale;

		if (dispMode==0) {
			ballPlot(gbx,gby,sc);

		} else if (dispMode==1) {
			linePlot(gbx,gby,sc);

		} else if (dispMode==2) {
			velocityPlot(gbx,gby,sc, 0.05);

		} else if (dispMode==3) {
			;

		}

		gOff.setColor(Color.blue);
		gOff.drawString("t="+(int)(md.getTime()*1.0e13+0.5)/10.0+" ps",10,40);
		gOff.setColor(Color.black);
		if (md.getStartSW()==0) {
			gOff.drawString("stopped",dispWidth/6*1+10,40);
		} else {
			gOff.drawString("started",dispWidth/6*1+10,40);
		}
		gOff.drawString("T cont.",dispWidth/6*3+10,40);
		gOff.drawString("Tc="+md.getContTemp()+" K",dispWidth/6*4+10,40);
	
		gOff.setColor(Color.blue);
		gOff.drawString("T="+(int)(md.getTemperature()*10+0.5)/10.0+" K",dispWidth/6*4+10,60);

		gOff.setColor(Color.black);
		gOff.drawString("view",dispWidth/6*5+10,40);

		gOff.drawString("Box="+(int)(md.getXMax()*1.0e10+0.5)/10.0+" x "+(int)(md.getYMax()*1.0e10+0.5)/10.0+" nm",10,60);
	}


	// ------------------------------------ plot methods -----------

	private void ballPlot(int gbx, int gby, double sc) {
		int i, ix, iy, ballSize, Nmt;

		Nmt = md.getNmt();
		ballSize = (int)(md.getDia()*sc);
		drawBox(gbx, gby, sc, ballSize);

		gOff.setColor(Color.blue);
		for (i=0; i<Nmt; i++) {
			ix = (int)(sc*md.getxx(i))+gbx;
			iy = (int)(sc*md.getyy(i))+gby;
			gOff.fillOval(ix-ballSize/2,iy-ballSize/2, ballSize, ballSize);
		}
	}

	private void linePlot(int gbx, int gby, double sc) {
		int i,ix,iy, j,jx,jy, ballSize, Nmt;
		double r0,rc2,r2, xij,yij;

		r0 = 1.12246*md.getDia();
		rc2 = r0*r0*1.1*1.1;
		Nmt = md.getNmt();
		ballSize = (int)(0.4*md.getDia()*sc);
		drawBox(gbx, gby, sc, ballSize);

		for (i=0; i<Nmt; i++) {
			ix = (int)(sc*md.getxx(i))+gbx;
			iy = (int)(sc*md.getyy(i))+gby;
			for (j=0; j<Nmt; j++) {
				xij = md.getxx(i)-md.getxx(j);
				yij = md.getyy(i)-md.getyy(j);
				r2 = xij*xij + yij*yij;
				if (r2<=rc2) {
					jx = (int)(sc*md.getxx(j))+gbx;
					jy = (int)(sc*md.getyy(j))+gby;
					gOff.setColor(Color.gray);
					gOff.drawLine(ix,iy, jx,jy);
				}
			}
			gOff.setColor(Color.blue);
			gOff.fillOval(ix-ballSize/2,iy-ballSize/2, ballSize, ballSize);
		}
	}

	private void velocityPlot(int gbx, int gby, double sc, double mag) {
		int i, ix, iy, ix2, iy2, ballSize,Nmt;

		Nmt = md.getNmt();
		ballSize = (int)(md.getDia()*sc);
		drawBox(gbx, gby, sc, ballSize);

		gOff.setColor(Color.blue);
		for (i=0; i<Nmt; i++) {
			ix = (int)(sc*md.getxx(i))+gbx;
			iy = (int)(sc*md.getyy(i))+gby;
			ix2 = ix+(int)(mag*md.getvx(i));
			iy2 = iy+(int)(mag*md.getvy(i));
			gOff.setColor(Color.getHSBColor(0.66f,0.2f,0.9f ));
			gOff.fillOval(ix-ballSize/2,iy-ballSize/2, ballSize, ballSize);
			gOff.setColor(Color.blue);
			gOff.drawLine(ix,iy, ix2, iy2);
		}
	}

	private void drawBox(int gbx, int gby, double sc, int ballSize) {
		int ix, iy, gball;
		double tmp;

		gball = ballSize/2;
		tmp = md.getTemperature();
		gOff.setColor(Color.gray); 
		if (md.getTempMode()==2) {
			gOff.setColor(Color.black); 
			if (tmp<md.getContTemp()) {
				gOff.setColor(Color.red);
			}
		}
		ix = (int)(sc*md.getXMax());
		iy = (int)(sc*md.getYMax());
		gOff.drawRect(gbx-gball,gby-gball,ix+2*gball,iy+2*gball);
	}
}




// ========================= molecular dynamics 2D class ===========

class MD2D implements Runnable {

	// preset field
	private double t = 0.0; // time (s)
	private double dt = 10.0*1.0e-15; // time division (s)

	private double xMax = 10.0e-9; // x-Box size (m)
	private double yMax = 10.0e-9; // y-Box size (m)

	private double sgm = 3.40e-10; // sigma of L-J potential for Ar (m)
	private double eps = 0.0104*1.602e-19; // epsilon of L-J potential for Ar (J)
	private double mas = 39.948*1.661e-27; // mass of L-J potential for Ar (kg)

	private int Nmt = 64; // number of molecules
	private int NN = Nmt;
	private double xx[] = new double[NN]; // i-th x-position
	private double yy[] = new double[NN]; // i-th y-position
	private double vx[] = new double[NN]; // i-th x-velocity
	private double vy[] = new double[NN]; // i-th y-velocity
	private double ffx[] = new double[NN]; // i-th x-force
	private double ffy[] = new double[NN]; // i-th y-force

	private int tempMode = 2; // 0-adiabatic 1-scaling 2-wall cont
	private double contTemp = 300.0; // control temperature (K)

	private int sleepTime = 1;
	private int stopSleepTime = 100;
	private int resetSW = 0;
	private int startSW = 1;
	private int stepSW = 0;
	private int statMode = 2;
	private int count = 0;


	// ------------------------------- class constructor -----------

	MD2D() {
		setInitialCondition();
	}


	// -------------------------------------- thread run -----------

	public void run() {
		while (true) {
			timeEvolution();
			count += 1;
			if (sleepTime>0) {
				try {
					Thread.sleep(sleepTime);
				} catch (InterruptedException e) { }
			}
		}
	}


	// --------------------------- set initial condition -----------

	private void setInitialCondition() {
		int i; 
		double s;

		t = 0.0;

		s = xMax/8.0;
		for (i=0; i<Nmt; i++) {
			xx[i] = s*(double)(i%8)+0.5*s;
			yy[i] = s*(double)(i/8)+0.5*s;
			vx[i] = 500.0*(Math.random()-0.5);
			vy[i] = 500.0*(Math.random()-0.5);
			ffx[i] = 0.0;
			ffy[i] = 0.0;
		}
		vAjustment();
	}


	// ---------------------------------- time evolution -----------

	private void timeEvolution() {

		if (resetSW==1) {
			setInitialCondition();
			resetSW = 0;
		}
	
		if (startSW==1) {
			timeStep();

		} else {
			if (stepSW==1) {
				timeStep();
				stepSW = 0;
			}
			try {
				Thread.sleep(stopSleepTime);
			} catch (InterruptedException e) { }
		}
	}

	private void timeStep() {
		int i;

		if (tempMode==1) {
			vAjustment();
		}
		for (i=0; i<20; i++) {
			timeStep1();
		}
	}

	private void timeStep1() {
		int i; 
		double dtv2, a;

		dtv2 = dt/2.0;
		t = t + dt;

		for (i=0; i<Nmt; i++) {
			a = dtv2/mas;
			vx[i] += a*ffx[i];
			vy[i] += a*ffy[i];
			xx[i] += vx[i]*dt;
			yy[i] += vy[i]*dt;
		}
		forceCalc();
		for (i=0; i<Nmt; i++) {
			a = dtv2/mas;
			vx[i] += a*ffx[i];
			vy[i] += a*ffy[i];
		}

		setBoundary();
	}

	private void forceCalc() {
		int i,j;
		double xij,yij,rij,f,fxij,fyij;

		for(i=0;i<Nmt;i++) {
			ffx[i] = 0.0;
			ffy[i] = 0.0;
		}

		for(i=0;i<Nmt;i++) {
			for(j=i+1;j<Nmt;j++) {
				xij = xx[i]-xx[j];
				yij = yy[i]-yy[j];
				rij = Math.sqrt(xij*xij+yij*yij);
				f = force(rij);
				fxij = f*xij/rij;
				fyij = f*yij/rij;

				ffx[i] += fxij;
				ffy[i] += fyij;

				ffx[j] += -fxij;
				ffy[j] += -fyij;
			}
		}
	}

	private double force(double r) {
		double ri,r3,r6;

		ri = sgm/r;
		r3 = ri*ri*ri;
		r6 = r3*r3;
		return (24.0*eps*r6*(2.0*r6-1.0)/r);
	}

	private void setBoundary() {
		int i; 
		double rr, tmp;

		rr = 1.0;
		if (tempMode==2) {
			tmp = temperature();
			rr = Math.sqrt(contTemp/tmp);
			if (rr<0.5) { rr = 0.5; } else if (rr>1.2){ rr=1.2; };
		}

		for (i=0; i<Nmt; i++) {
			if (xx[i] < 0.0) { 
				xx[i] = 0.0; vx[i] = -rr*vx[i]; vy[i] = rr*vy[i]; 
			}
			if (xx[i] > xMax) {
				xx[i] = xMax; vx[i] = -rr*vx[i]; vy[i] = rr*vy[i]; 
			}
			if (yy[i] < 0.0) { 
				yy[i] = 0.0; vx[i] = rr*vx[i]; vy[i] = -rr*vy[i]; 
			}
			if (yy[i] > yMax) {
				yy[i] = yMax; vx[i] = rr*vx[i]; vy[i] = -rr*vy[i];
			}
		}
	}


	// ----------------------------------------- utility -----------

	private double temperature() {
		int i;
		double s;

		s = 0.0; 
		for (i=0; i<Nmt; i++) {
			s += 0.5*mas*(vx[i]*vx[i] + vy[i]*vy[i]);
		}
		return ( s/((double)Nmt*1.38e-23) );
	}

	//

	private void vAjustment() {
		int i;
		double tmp, r;

		tmp = temperature();
		r = Math.sqrt(contTemp/tmp);
		for (i=0; i<Nmt; i++) {
			vx[i] = r*vx[i];
			vy[i] = r*vy[i];
		}
	}


	// ------------------------------------- I/O methods -----------

	// control
	public void reset() { resetSW = 1; }
	public void setStartSW(int sw) { startSW = sw; }
	public int getStartSW() { return startSW; }
	public void setStepSW() { stepSW = 1; }
	public int getCount() { return count; }

	public void setTempMode(int m) { tempMode = m; }
	public int getTempMode() { return tempMode; }
	public void setContTemp(double tmp) { contTemp = tmp; }
	public double getContTemp() { return contTemp; }

	// get data
	public int getNmt() { return Nmt; }
	public double getXMax() { return xMax; }
	public double getYMax() { return yMax; }
	public double getDia() { return sgm; }

	public double getTime() { return t; }
	public double getxx(int i) { return xx[i]; }
	public double getyy(int i) { return yy[i]; }
	public double getvx(int i) { return vx[i]; }
	public double getvy(int i) { return vy[i]; }
	public double getTemperature() { return temperature(); }
}