Rotating and Translating an Image

Question

I am making a game with a tank that can rotate and move forwards and backwards.
I am able to get the tank Image to rotate, but when I call a translation, it resets the image back to its original image. How can I fix this?

Answer 1

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.event.*;
public class TankGame extends JPanel {
    Walker walker = new Walker(this);
    BufferedImage image;
    AffineTransform at = new AffineTransform();
    Point2D.Double loc = new Point2D.Double(200,150);
    double theta = 0;
    double t = 3.0;
    boolean goAhead = true;
    public TankGame(BufferedImage image) {
        this.image = image;
        setTransform();
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.drawRenderedImage(image, at);
        //g2.setPaint(Color.red);
        //g2.fill(new Ellipse2D.Double(loc.x-2, loc.y-2, 4, 4));
    public synchronized void step() {
        int sign = goAhead ? 1 : -1;
        double x = loc.x + sign*t*Math.cos(theta);
        double y = loc.y + sign*t*Math.sin(theta);
        loc.setLocation(x, y);
        setTransform();
        repaint();
    private void setTransform() {
        double x = loc.x - image.getWidth()/2;
        double y = loc.y - image.getHeight()/2;
        at.setToTranslation(x, y);
        at.rotate(theta, image.getWidth()/2, image.getHeight()/2);
    private JPanel getUIPanel() {
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(1,0,1,0);
        gbc.weightx = 1.0;
        String[] ids = { "ahead", "stop", "back" };
        ActionListener al = new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String ac = e.getActionCommand();
                if(ac.equals("stop")) {
                    walker.stop();
                } else {
                    if(ac.equals("ahead")) {
                        goAhead = true;
                    } else if(ac.equals("back")) {
                        goAhead = false;
                    walker.start();
        for(int j = 0; j < ids.length; j++) {
            JButton button = new JButton(ids[j]);
            button.addActionListener(al);
            if(j == ids.length-1)
                gbc.gridwidth = GridBagConstraints.REMAINDER;
            panel.add(button, gbc);
        JSlider slider = new JSlider(-180, 180, 0);
        slider.addChangeListener(new ChangeListener() {
            public void stateChanged(ChangeEvent e) {
                int angle = ((JSlider)e.getSource()).getValue();
                theta = Math.toRadians(angle);
                setTransform();
                repaint();
        gbc.gridwidth = 3;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        panel.add(slider, gbc);
        return panel;
    public static void main(String[] args) throws IOException {
        String path = "images/geek/geek----t.gif";
        BufferedImage image = ImageIO.read(new File(path));
        TankGame test = new TankGame(image);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(test);
        f.add(test.getUIPanel(), "Last");
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
class Walker implements Runnable {
    TankGame game;
    Thread thread;
    boolean moving = false;
    long delay = 100;
    public Walker(TankGame tg) {
        game = tg;
    public void run() {
        while(moving) {
            try {
                Thread.sleep(delay);
            } catch(InterruptedException e) {
                moving = false;
            game.step();
    public void start() {
        if(!moving) {
            moving = true;
            thread = new Thread(this);
            thread.setPriority(Thread.NORM_PRIORITY);
            thread.start();
    public void stop() {
        moving = false;
        if(thread != null)
            thread.interrupt();
        thread = null;
}