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Need help on Java animation

Posted on 2006-11-25
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Last Modified: 2008-02-01
Hi there, experts.

I was wondering if anyone here can help me out on my "Trucks" program. I set up three files. One java file deals with positioning the truck on the panel, the second have to do with constructing the truck, and the third have to do with actually viewing the program of my truck. Now, i want to move 3 of the 5 trucks, but I'm not to sure how to do this properly. Noticed that I named my files "Car" because I was drawing cars @ first, and then I changed them to trucks, and I'm too lazy to renamed them (lol). The one file that I really need help with is the "CarComponent" file, where I need to modify that file so that the trucks can actually move. I tried, but failed. Before I inserted "public void animateCar()" and "public void playAnimation()", I was able to display 5 trucks. I'm not too familiar with java animation, but if anyone here can help me, that would be great. Thanks.
============================================
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JComponent;
import java.math.BigInteger;
import java.math.BigDecimal;

public class CarComponent extends JComponent
{

      public void sleep()
      {
            try
            {
                  Thread thread;
                  Thread.sleep(60);
            }
                  catch (Exception e){}
      }

      public void paintComponent(Graphics g)
      {
            Graphics2D g2 = (Graphics2D) g;

            Car car1 = new Car(0, 0);

            int x = getWidth() - Car.WIDTH;
            int y = getHeight() - Car.HEIGHT;

            Car car2 = new Car(x, y);



            Car car3 = new Car(x - 185, y - 150);
            Car car4 = new Car(x - 50, y - 150);
            Car car5 = new Car(x - 380, y - 150);


            car1.draw(g2);
            car2.draw(g2);
            car3.draw(g2);
            car4.draw(g2);
            car5.draw(g2);
      }

      public void animateCar(Graphics gr, Car car, int deltaX, int deltaY)
      {
           car.erase(gr);
           car.setX(Car.getX() + deltaX);
           car.getY(Car.getY() + deltaY);
           car.draw(gr);
      }

      public void playAnimation()
      {
          Graphics gr = getGraphics();
          for (int i = 0; i < 200; i = i + 3)
          {
            animateCar(gr, car3, i, 0);
            animateCar(gr, car4, i, Math.round(-i * 1.5));
            animateCar(gr, car5, 0, i);
            sleep();
          }
      }
}
=======================================
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;

public class Car
{
      public Car(int x, int y)
      {
            xLeft = x;
            yTop = y;
      }

      public void draw(Graphics2D g2)
      {
            Rectangle body = new Rectangle(xLeft, yTop, 120, 10);
            Rectangle window = new Rectangle(xLeft + 30, yTop - 50, 15, 15);
            Ellipse2D.Double frontTire = new Ellipse2D.Double(xLeft + 10, yTop + 10, 20, 20);
            Ellipse2D.Double rearTire = new Ellipse2D.Double(xLeft + 85, yTop + 10, 20, 20);

            Point2D.Double r1 = new Point2D.Double(xLeft, yTop - 35);
            Point2D.Double r2 = new Point2D.Double(xLeft, yTop);
            Point2D.Double r3 = new Point2D.Double(xLeft + 50, yTop);
            Point2D.Double r4 = new Point2D.Double(xLeft + 50, yTop + 10);
            Point2D.Double r5 = new Point2D.Double(xLeft + 35, yTop - 60);
            Point2D.Double r6 = new Point2D.Double(xLeft + 50, yTop - 60);
            Point2D.Double r7 = new Point2D.Double(xLeft + 50, yTop);

            Line2D.Double frontWindshield = new Line2D.Double(r1, r2);
            Line2D.Double roofTop = new Line2D.Double(r5, r6);
            Line2D.Double rearWindshield = new Line2D.Double(r6, r7);
            Line2D.Double anotherFront = new Line2D.Double(r1, r5);

            g2.draw(body);
            g2.draw(window);
            g2.draw(frontTire);
            g2.draw(rearTire);
            g2.draw(frontWindshield);
            g2.draw(roofTop);
            g2.draw(rearWindshield);
            g2.draw(anotherFront);
      }

      public static int WIDTH = 60;
      public static int HEIGHT = 30;

      private int xLeft;
      private int yTop;
}
=============================================
import javax.swing.JFrame;

public class CarViewer
{
      public static void main(String[] args)
      {
            JFrame frame = new JFrame();

            final int FRAME_WIDTH = 800;
            final int FRAME_HEIGHT = 400;

            frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
            frame.setTitle("Two Cars");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

            CarComponent component = new CarComponent();
            frame.add(component);
            frame.setVisible(true);
      }
}
===========================================
0
Comment
Question by:Daving
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9 Comments
 
LVL 10

Accepted Solution

by:
ADSLMark earned 1400 total points
ID: 18011477
Ok, i got your copy working, but the trucks are moving all kind of ways.. so I changed some code and made them ride some to the left (beginning at the right)..
It should give you an idea on the thread issue.

============================================
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JComponent;
import java.math.BigInteger;
import java.math.BigDecimal;
import java.util.LinkedList;

public class CarComponent extends JComponent
{

    private LinkedList<Car> cars;

    public CarComponent(int width, int height)
    {
        this.setSize(width, height);

        int x = width - Car.WIDTH;
        int y = height - Car.HEIGHT;

        cars = new LinkedList<Car>();
        cars.add(new Car(x, Car.HEIGHT));
        cars.add(new Car(x, Car.HEIGHT*2+5));
        cars.add(new Car(x, Car.HEIGHT*3+10));
        cars.add(new Car(x, Car.HEIGHT*4+15));
        cars.add(new Car(x, Car.HEIGHT*5+20));

        CarThread carThread = new CarThread(this);
        carThread.start();
    }

    public void paintComponent(Graphics g)
    {
        Graphics2D g2 = (Graphics2D) g;

        for(Car car : cars)
            car.draw(g2);
    }

    public void animateCar(Car car, int deltaX, int deltaY)
    {
        car.setX(car.getX() + deltaX);
        car.setY(car.getY() + deltaY);
    }

    public void moveCars(int i)
    {
        animateCar(cars.get(2), i, 0);
        animateCar(cars.get(3), i, 0);
        animateCar(cars.get(4), i, 0);

        this.repaint();
    }
}
============================================
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;

public class Car
{
     public Car(int x, int y)
     {
          xLeft = x;
          yTop = y;
     }

     public void draw(Graphics2D g2)
     {
          Rectangle body = new Rectangle(xLeft, yTop, 120, 10);
          Rectangle window = new Rectangle(xLeft + 30, yTop - 50, 15, 15);
          Ellipse2D.Double frontTire = new Ellipse2D.Double(xLeft + 10, yTop + 10, 20, 20);
          Ellipse2D.Double rearTire = new Ellipse2D.Double(xLeft + 85, yTop + 10, 20, 20);

          Point2D.Double r1 = new Point2D.Double(xLeft, yTop - 35);
          Point2D.Double r2 = new Point2D.Double(xLeft, yTop);
          Point2D.Double r3 = new Point2D.Double(xLeft + 50, yTop);
          Point2D.Double r4 = new Point2D.Double(xLeft + 50, yTop + 10);
          Point2D.Double r5 = new Point2D.Double(xLeft + 35, yTop - 60);
          Point2D.Double r6 = new Point2D.Double(xLeft + 50, yTop - 60);
          Point2D.Double r7 = new Point2D.Double(xLeft + 50, yTop);

          Line2D.Double frontWindshield = new Line2D.Double(r1, r2);
          Line2D.Double roofTop = new Line2D.Double(r5, r6);
          Line2D.Double rearWindshield = new Line2D.Double(r6, r7);
          Line2D.Double anotherFront = new Line2D.Double(r1, r5);

          g2.draw(body);
          g2.draw(window);
          g2.draw(frontTire);
          g2.draw(rearTire);
          g2.draw(frontWindshield);
          g2.draw(roofTop);
          g2.draw(rearWindshield);
          g2.draw(anotherFront);
     }

     public int getX()
     {
         return xLeft;
     }

     public int getY()
     {
         return yTop;
     }

     public void setX(int xLeft)
     {
         this.xLeft = xLeft;
     }

     public void setY(int yTop)
     {
         this.yTop = yTop;
     }

     public static int WIDTH = 120;
     public static int HEIGHT = 70;

     private int xLeft;
     private int yTop;
}
============================================
import javax.swing.JFrame;

public class CarViewer
{
     public static void main(String[] args)
     {
          JFrame frame = new JFrame();

          final int FRAME_WIDTH = 800;
          final int FRAME_HEIGHT = 400;

          frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
          frame.setTitle("Two Cars");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

          CarComponent component = new CarComponent(FRAME_WIDTH, FRAME_HEIGHT);
          frame.add(component);
          frame.setVisible(true);
     }
}
============================================
class CarThread extends Thread implements Runnable
{
    private CarComponent carComponent;
    public CarThread(CarComponent carComponent)
    {
        this.carComponent = carComponent;
    }

    public void run()
    {
        for (int i = 0; i < 200; i = i + 3)
        {
            try
            {
                this.carComponent.moveCars(-5);

                this.sleep(60);
            }
            catch (InterruptedException ie)
            {
                System.out.println("Interrupt exception.");
            }
        }
    }
}
============================================

Good luck.
Mark
0
 
LVL 10

Expert Comment

by:ADSLMark
ID: 18011507
Some design issues..

You have the following classes: Car, CarThread, CarViewer, CarComponent
In the code above (mine and yours), the implementation is a bit inflexible. I might have some better code later, but let me explain first a better idea.

The CarViewer is the main frame. Next is the CarComponent which can be added to a container to show a number of cars. The CarComponent should have an add method which allows the CarViewer to add cars. Thus the CarComponent holds a list of the Cars in it's component. Now you can choose to have every Car in a single thread or every CarComponent in a single thread. I think the later is preferable, since it's more scalable and less intensive. The Car class should only be concerned with drawing itself and keeping the position and the CarThread should only be concerned with the regular interval movement of the cars.

So in Java terms it should look like:

==CarViewer==
public static void main(String[] args);

==CarComponent==
private LinkedList<Car> cars;
private CarThread animation;

public void addCar(Car car);
public void removeCar(Car car);
public void startAnimation();
public void stopAnimation();

==Car==
private int x;
private int y;
private int width;
private int height;

public void move(int dx, int dy);

==CarThread==
public CarThread(LinkedList<Car> cars);
public void run();

Sth. like this.. I will start coding now, let me see if I can make some nice setup.

Mark
0
 

Author Comment

by:Daving
ID: 18011525
Thank you so much for that, Mark. You deserve my 350 points :)
0
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Author Comment

by:Daving
ID: 18011544
Mark, if you have anything more to add, email me:

Dragon_316ca@yahoo.ca
0
 
LVL 10

Expert Comment

by:ADSLMark
ID: 18011546
Do you still want the code for the design i suggested?

Mark
0
 

Author Comment

by:Daving
ID: 18011551
Yeah sure.


0
 
LVL 10

Expert Comment

by:ADSLMark
ID: 18011624
Here the code:

===CarViewer===
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JFrame;

//Class is the visible frame. For now only
//consisting of a CarComponent and some buttons
//to start and stop animation.
class CarViewer extends JFrame implements ActionListener
{
    private final static int FRAME_WIDTH = 800;
    private final static int FRAME_HEIGHT = 400;

    private CarComponent carComponent;

    private JButton butStart;
    private JButton butStop;

    //Constructor
    public CarViewer()
    {
        //Frame properties
        this.setSize(FRAME_WIDTH, FRAME_HEIGHT);
        this.setTitle("Cars Example");
        this.setLayout(new BorderLayout());
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Add CarComponent
        this.carComponent = new CarComponent();
        this.add(this.carComponent, BorderLayout.CENTER);

        //Add some cars
        this.carComponent.addCar(new Car(10, 10));
        this.carComponent.addCar(new Car(10, Car.HEIGHT+20));
        this.carComponent.addCar(new Car(10, Car.HEIGHT*2+30));
        this.carComponent.addCar(new Car(10, Car.HEIGHT*3+40));
        this.carComponent.addCar(new Car(10, Car.HEIGHT*4+50));
        this.carComponent.addCar(new Car(10, Car.HEIGHT*5+60));

        //Add buttons
        this.butStart = new JButton("Start");
        this.butStart.addActionListener(this);
        this.butStart.setActionCommand("start");
        this.butStop = new JButton("Stop");
        this.butStop.addActionListener(this);
        this.butStop.setActionCommand("stop");
        this.butStop.setEnabled(false);

        JPanel pnlButtons = new JPanel();
        pnlButtons.add(this.butStart);
        pnlButtons.add(this.butStop);
        this.add(pnlButtons, BorderLayout.NORTH);
    }

    //Handle actions
    public void actionPerformed(ActionEvent ae)
    {
        if("start".equals(ae.getActionCommand()))
        {
            this.butStop.setEnabled(true);
            this.butStart.setEnabled(false);

            this.carComponent.startAnimation();
        }
        else if("stop".equals(ae.getActionCommand()))
        {
            this.butStart.setEnabled(true);
            this.butStop.setEnabled(false);

            this.carComponent.stopAnimation();
        }
    }

    //Program entry
    public static void main(String[] args)
    {
        CarViewer carViewer = new CarViewer();
        carViewer.setVisible(true);
    }
}
===CarComponent===
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JComponent;
import java.util.LinkedList;

//Class for holding a number of cars. All tasks
//are delegated to the objects. This component
//starts and stops the CarThread.
class CarComponent extends JComponent
{
    private LinkedList<Car> cars;
    private CarThread carThread;

    //Constructor
    public CarComponent()
    {
        this.cars = new LinkedList<Car>();
        this.carThread = new CarThread(this);
    }

    //Paint component
    public void paintComponent(Graphics g)
    {
        Graphics2D g2 = (Graphics2D) g;

        //Loop cars
        for(Car car : this.cars)
            car.draw(g2);
    }

    //Add car to list
    public void addCar(Car car)
    {
        this.cars.add(car);
    }

    //Remove car from list
    public void removeCar(Car car)
    {
        this.cars.remove(car);
    }

    //Returns list of cars
    public LinkedList<Car> getCars()
    {
        return this.cars;
    }

    //Start animation
    public void startAnimation()
    {
        this.carThread.startAnimation();
    }

    //Stop animation
    public void stopAnimation()
    {
        this.carThread.stopAnimation();
    }
}
===CarThread===
import java.util.LinkedList;

//Class is only concerned with moving the cars on
//a specific interval.
class CarThread implements Runnable
{
    private final static int INTERVAL = 60;

    private CarComponent carComponent;
    private boolean running;

    //Constructor
    public CarThread(CarComponent carComponent)
    {
        this.carComponent = carComponent;
        this.running = false;
    }

    //Thread loop
    public void run()
    {
        this.running = true;
        while(running)
        {
            try
            {
                //Move cars
                for(Car car : this.carComponent.getCars())
                {
                    car.move(5, 0);
                }

                //Repaint
                this.carComponent.repaint();

                //Sleep for INTERVAL ms
                Thread.sleep(INTERVAL);
            }
            catch (InterruptedException ie)
            {
                System.out.println("Interrupt exception. Animation will stop now.");
                this.running = false;
            }
        }
    }

    //Start thread
    public void startAnimation()
    {
        if(!this.running)
            new Thread(this).start();
    }

    //Stop thread
    public void stopAnimation()
    {
        this.running = false;
    }
}
===Car===
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;

//Class is only concerned with drawing the car.
class Car
{
    public final static int WIDTH = 120;
    public final static int HEIGHT = 70;

    private int x;
    private int y;

    //Constructor
    public Car(int x, int y)
    {
        this.x = x;
        this.y = y;
    }

    //Draw car
    public void draw(Graphics2D g2)
    {
        Rectangle body = new Rectangle(this.x, this.y, 120, 10);
        Rectangle window = new Rectangle(this.x + 30, this.y - 50, 15, 15);

        Ellipse2D.Double frontTire = new Ellipse2D.Double(this.x + 10, this.y + 10, 20, 20);
        Ellipse2D.Double rearTire = new Ellipse2D.Double(this.x + 85, this.y + 10, 20, 20);

        Point2D.Double r1 = new Point2D.Double(this.x, this.y - 35);
        Point2D.Double r2 = new Point2D.Double(this.x, this.y);
        Point2D.Double r3 = new Point2D.Double(this.x + 50, this.y);
        Point2D.Double r4 = new Point2D.Double(this.x + 50, this.y + 10);
        Point2D.Double r5 = new Point2D.Double(this.x + 35, this.y - 60);
        Point2D.Double r6 = new Point2D.Double(this.x + 50, this.y - 60);
        Point2D.Double r7 = new Point2D.Double(this.x + 50, this.y);

        Line2D.Double frontWindshield = new Line2D.Double(r1, r2);
        Line2D.Double roofTop = new Line2D.Double(r5, r6);
        Line2D.Double rearWindshield = new Line2D.Double(r6, r7);
        Line2D.Double anotherFront = new Line2D.Double(r1, r5);

        g2.draw(body);
        g2.draw(window);
        g2.draw(frontTire);
        g2.draw(rearTire);
        g2.draw(frontWindshield);
        g2.draw(roofTop);
        g2.draw(rearWindshield);
        g2.draw(anotherFront);
    }

    //Move car
    public void move(int dx, int dy)
    {
        this.x += dx;
        this.y += dy;
    }
}

I did not change the drawing of the car, so now they ride backwards, but it shouldn't be difficult to adjust now. This is a pretty flexible design if you ask me. I am pretty proud at this piece of code, if I might say so myself. :-)

Have fun.
Mark
0
 

Author Comment

by:Daving
ID: 18011857
How can you make the truck to move "in reverse"? Please tell me via email: Dragon_316ca@yahoo.ca

thanks
0
 
LVL 10

Expert Comment

by:ADSLMark
ID: 18011868
Use negative numbers for the move(int dx, int dy) method.

I believe it is not allowed to sent email if the question is posted on this forum.. since you would get questions without answers, being answered. :-)

Mark
0

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