import java.awt.*;

import java.awt.event.*;

import java.lang.*;

import java.lang.Math;

import java.text.*;



public class Circular2 extends java.applet.Applet 

  implements Runnable {



  Canvas oscillators;

  Label ballMassLabel, stringTensionLabel, 

        ballMassS, stringTensionS;

  Button Start;

  Thread runner;

  Scrollbar ballMassscroll, stringTensionscroll;

  int xpos, ypos, ballMass, stringTension, ballDiameter, 

       ballRadius, yLine, ovalX1, ovalX2, ovalY1, ovalY2;

  double x, y, ballM, ballW, ballV, tension, tX, tY, stringA, radius;

  double pi = 3.141592653589793238468;



  Image offscreenImg;

  Graphics offscreenG;



  boolean startFlag;



  void buildConstraints(GridBagConstraints gbc, int gx, int gy, 

      int gw, int gh,

      int wx, int wy) {

	gbc.gridx = gx;

	gbc.gridy = gy;

	gbc.gridwidth = gw;

	gbc.gridheight = gh;

	gbc.weightx = wx;

	gbc.weighty = wy;

  }



  public void init() {

    GridBagLayout gridbag = new GridBagLayout();

    GridBagConstraints constraints = new GridBagConstraints();

    setLayout(gridbag);





    // ball mass text

    buildConstraints(constraints, 0, 0, 1, 1, 20, 5);

    constraints.fill = GridBagConstraints.NONE;

    constraints.anchor = GridBagConstraints.EAST;

    Label ballMassLabel = new Label("Mass of the ball (grams):", Label.CENTER);

    gridbag.setConstraints (ballMassLabel, constraints);

    add(ballMassLabel);



    // ball mass scrollbar label

    buildConstraints(constraints, 2, 0, 1, 1, 20, 0);

    constraints.fill = GridBagConstraints.HORIZONTAL;

    ballMassS = new Label("800", Label.LEFT);

    ballMass = 800;

    gridbag.setConstraints (ballMassS, constraints);

    add(ballMassS);



    // ball mass scrollbar

    buildConstraints(constraints, 1, 0, 1, 1, 20, 0);

    constraints.fill = GridBagConstraints.HORIZONTAL;

    constraints.anchor = GridBagConstraints.WEST;

    ballMassscroll = new Scrollbar(Scrollbar.HORIZONTAL, 800, 20, 100, 1000);

    gridbag.setConstraints (ballMassscroll, constraints);

    add(ballMassscroll);



    // string tension text

    buildConstraints(constraints, 0, 1, 1, 1, 20, 5);

    constraints.fill = GridBagConstraints.NONE;

    constraints.anchor = GridBagConstraints.EAST;

    Label stringTensionLabel = new Label("Tension in the string(N):", Label.CENTER);

    gridbag.setConstraints (stringTensionLabel, constraints);

    add(stringTensionLabel);



    // string tension scrollbar label

    buildConstraints(constraints, 2, 1, 1, 1, 20, 0);

    constraints.fill = GridBagConstraints.HORIZONTAL;

    stringTensionS = new Label("15", Label.LEFT);

    stringTension = 15;

    gridbag.setConstraints (stringTensionS, constraints);

    add(stringTensionS);



    // string tension scrollbar

    buildConstraints(constraints, 1, 1, 1, 1, 20, 0);

    constraints.fill = GridBagConstraints.HORIZONTAL;

    constraints.anchor = GridBagConstraints.WEST;

    stringTensionscroll = new Scrollbar(Scrollbar.HORIZONTAL, 15, 1, 10, 20);

    gridbag.setConstraints (stringTensionscroll, constraints);

    add(stringTensionscroll);



    // Start button

    buildConstraints(constraints, 1, 2 , 1, 1, 0, 10);

    constraints.fill = GridBagConstraints.HORIZONTAL;

    constraints.anchor = GridBagConstraints.WEST;

    Start = new Button("Start");

    gridbag.setConstraints (Start, constraints);

    add(Start);



    // canvas

    buildConstraints(constraints, 0, 3, 3, 1, 0, 80);

    constraints.fill = GridBagConstraints.HORIZONTAL;

    oscillators = new Canvas();

    gridbag.setConstraints (oscillators, constraints);

    add(oscillators);



    offscreenImg = createImage(this.size().width, this.size().height);

    offscreenG = offscreenImg.getGraphics();

  }



  public void start() {

    if (runner == null); {

      runner = new Thread(this);

      runner.start();

    }

  }



  public void stop() {

    if (runner != null) {

      runner.stop();

      runner = null;

    }

  }



  public void run() {



    int i, temp;

    double xOrigin, yOrigin, xScale, yScale, kAngle, t, deltat, yL,

        stringL;

    ballDiameter = 16;

    ballRadius = 8;

    yOrigin = 250.0;

    xOrigin = 150.0;

    kAngle = pi/180.0;

    deltat = 0.02;

    startFlag = false;



    while (true) {

      t = 0.0;

      ballM = ballMass/1000.0;

      ballW = ballM*9.8;

      tension = stringTension;

      stringL = 0.5;

      ballV = Math.sqrt(tension/(ballM*stringL));



      tY = ballW;

      tX = Math.sqrt(tension*tension - tY*tY);

      stringA = (Math.atan(tX/tY));

      radius = 100.0*stringL*Math.sin(stringA);     

      xScale = 2.0*radius;

      yL = 200.0*stringL*Math.cos(stringA);

      yLine = (int)(yL);

      yScale = 0.3*xScale;

      stringA = stringA / kAngle;



      x = xOrigin-xScale;

      xpos = (int)(x);

      y = yOrigin+yLine;

      ypos = (int)(y);

      ovalX1 = xpos;

      ovalX2 = (int)(xOrigin+xScale);

      ovalY1 = (int)(y-yScale);

	ovalY2 = (int)(y+yScale);

      

      while (startFlag) {



        while (startFlag) { 

          t = t+deltat;

          x = xOrigin-xScale*Math.cos(ballV*t);

          y = yOrigin+yLine+yScale*Math.sin(ballV*t);



          xpos = (int)(x);

          ypos = (int)(y);



         repaint();

          try { Thread.sleep(100); }

          catch (InterruptedException e) { }

       } 

    }



     repaint();

     try { Thread.sleep(1); }

     catch (InterruptedException e) { }

     }

  }



  public void update(Graphics g) {

    paint(g);

  }

     

  public void paint(Graphics g) {



    int i;



     // Draw background

   offscreenG.setColor(Color.lightGray);

   offscreenG.fillRect(0,0,500,200);

   offscreenG.setColor(Color.white);

   offscreenG.fillRect(0,200,500,400);



   // Draw mass

    NumberFormat nf = NumberFormat.getInstance();

    nf.setMaximumFractionDigits(4);

    offscreenG.setColor(Color.black);

    offscreenG.drawOval(ovalX1,ovalY1,ovalX2-ovalX1,ovalY2-ovalY1);

    offscreenG.drawString("Radius of path = " + nf.format(radius) + " cm", 310, 360);

    offscreenG.setColor(Color.blue);

    offscreenG.drawLine(150, 250,xpos, ypos);

    offscreenG.drawString("Tension in the string", 310, 240);

    offscreenG.drawString("X component : Tx = " + nf.format(tX) + " N", 320, 260);

    offscreenG.drawString("Y component : Ty = " + nf.format(tY) + " N", 320, 280);

    offscreenG.drawString("magnitude : T = " + nf.format(tension) + " N", 320, 300);

    offscreenG.drawString("Angle of string = " + nf.format(stringA) + " degrees", 310, 320);



    offscreenG.setColor(Color.red);

    offscreenG.drawString("Weight of the ball = " + nf.format(ballW) + " N", 310, 220);

    offscreenG.drawString("Ball speed = " + nf.format(radius*ballV/100.0) + " m/s", 310, 340);

    if (ypos>250+yLine) {

      offscreenG.setColor(Color.blue);

      offscreenG.drawLine(150, 250+yLine,150, 250);  

      offscreenG.setColor(Color.red);

      offscreenG.fillOval(xpos-ballRadius,ypos-ballRadius,ballDiameter,ballDiameter);

    }

    else {

      offscreenG.setColor(Color.red);

      offscreenG.fillOval(xpos-ballRadius,ypos-ballRadius,ballDiameter,ballDiameter);

      offscreenG.setColor(Color.blue);

      offscreenG.drawLine(150, 250+yLine,150, 250);  

    }

    g.drawImage(offscreenImg,0,0,this);

  }



  public void destroy() {

     offscreenG.dispose();

  }



  public boolean action (Event evt, Object arg) {



    if (evt.target instanceof Button) {



      if ((Button)evt.target == Start) {



        if (Start.getLabel().equals("Start")) {

          startFlag = true;

          Start.setLabel("Reset");

        }



        else {

          startFlag = false;

          Start.setLabel("Start");

        }

      }

    }

    else return super.action(evt, arg);

    return true;

  }



  public boolean handleEvent(Event evt) {



    if (evt.target instanceof Scrollbar) {

      if ((Scrollbar)evt.target == ballMassscroll) {

        ballMass = ((Scrollbar)evt.target).getValue();

        ballMassS.setText(String.valueOf(ballMass));

      }

      else if ((Scrollbar)evt.target == stringTensionscroll) {

        stringTension = ((Scrollbar)evt.target).getValue();

        stringTensionS.setText(String.valueOf(stringTension));

      }

	repaint();

    }

    else return super.handleEvent(evt);

    return true;

  }

}