Repainting Jpanel timer (60fps) 12% CPU usage

[Ash Whin]

Hey guys, I had a thread in another forum but its too long to read so... This ones the extension of the same project I've been working on. I've figured out that lots of the lagginess was coming from the lack of synchronisation and the bad allocation of elements so I corrected that and now the physics code part is a lot better, and I tested the program with and without the JPanel.repaint() and found an increase of 8% CPU to 20% CPU.

The code for repainting goes like this:

public class Bounce {
    public static void main(String[] args) {
         //load buffered images and array lists containing the entities
         //add event listeners and set up JFrame

         new Thread() { public void run() {
            long lastlong = System.nanoTime();
            float delta = 0;
            long timer = System.currentTimeMillis();
            final double physicstick = 1000000000 / 140;

            while (true) {
                long now = System.nanoTime();
                delta += (now - lastlong) / physicstick;
                long lastrender = System.nanoTime();
                lastlong = now;
                while (delta >= 1) {
                    delta--;
                    //physics code 8% CPU, is that normal?
                }
                
                GamePanel.repaint();
                lastrender = now;

                while (now - lastrender < (1000000000 / 60)) {
                    try {
                        Thread.sleep(1);
                        //Without sleeping there is a 100% CPU usage CRAZY!
                    } catch (InterruptedException ie) {
                    }
                    now = System.nanoTime();
                }
           }}}.start();
      }

      //JPanel for double buffering
      private static final class GamePanel extends JPanel {
           @Override public void paint(Graphics G) {
            //This is the code for repainting! EVEN WHEN I do not put code in paint(Graphics) it still takes up like 10% CPU. I do not know what is happening here, I also tried using Component but the results were worse so... Help me!

            Graphics2D d = (Graphics2D)G;
            if (upwards < thiswidth / 20) G.drawImage(ground, 0, thisheight - thiswidth / 20 - (int)upwards, thiswidth, thiswidth / 20, null);
            synchronized (platforms) {
                for (int i = 0; i < platforms.size(); i++) {
                    ArrayList ar = platforms.get(i);
                    synchronized (ar) {
                        for (int ii = 0; ii < ar.size(); ii++) {
                            Platform plat = (Platform) ar.get(ii);
                            final int finint = plat.deltay - 32 - (int) upwards;
                            if (finint < thisheight && finint > -50) {
                                if (plat.type == 0) G.drawImage(platform, plat.deltax - 128, finint, 256, 64, null);
                                else if (plat.type == 1) G.drawImage(mover, plat.deltax - 128, finint, 256, 64, null);
                                else {
                                    G.drawImage(third, plat.deltax - 96, finint, 192, 64, null);
                                    if (flash.contains(plat)) {
                                        d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, plat.flashy));
                                        G.drawImage(flashie, plat.deltax - 252, finint - 48, 480, 152, null);
                                        d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1f));

                                    }
                                }
                            }


                            if (plat == touchingplatform) {
                                d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, glo));

                                G.drawImage(glowing, plat.deltax - 200, plat.deltay - 80 - (int) upwards, 400, 160, null);
                                d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1f));
                            }

                        }
                    }
                }
            }
            for (Powerup powerie : power) {
                if (powerie.type == 0) G.drawImage(feather, powerie.x, powerie.y - (int)upwards, 73, 73, null);
                else if (powerie.type == 1) G.drawImage(boots, powerie.x, powerie.y - (int)upwards, 73, 73, null);
            }

            if (height < -upwards - 120) {
                BufferedImage flame = fire.get(flames / 8);
                G.drawImage(flame, 0, (int)(-thisheight * 0.59f), thiswidth, thiswidth, null);
                G.drawImage(respawn, thiswidth / 6, thisheight / 4, thiswidth / 3 * 2, thisheight / 2, null);
            }

            else if (character == 0) {
                BufferedImage mario = guy.get(frame);
                G.drawImage(mario, dir ? (int) forward : (int) forward + 165, thisheight - 165 - (int) height - (int)upwards, dir ? 176 : -176, 140, null);
                fam = 10;
            }
            else if (character == 1) {
                BufferedImage reap = reaper.get(frame);
                G.drawImage(reap, dir ? (int) forward : (int) forward + 205, thisheight - 190 - (int) height - (int)upwards, dir ? 192 : -192, 192, null);
                fam = 9;
            }
            else if (character == 2) {
                BufferedImage boom = hunter.get(frame);
                G.drawImage(boom, dir ? (int) forward : (int) forward + 165, thisheight - 185 - (int) height - (int)upwards, dir ? 192 : -192, 173, null);
                fam = 7;

            }
            else if (character == 3) {
                BufferedImage boom = gun.get(frame);
                G.drawImage(boom, dir ? (int) forward : (int) forward + 165, thisheight - 210 - (int) height - (int)upwards, dir ? 192 : -192, 192, null);
                fam = 5;
            }



            d.setFont(fo);
            d.setColor(Color.WHITE);
            d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            G.drawString("Score " + score, 10, 70);
            G.drawString("High Score " + max, 10, 110);

            G.dispose();
        }
    }
}

[Les Morgan]

What you are saying is not normal.  First off you need to make your program event driven, here is a thread that, I believe, does a decent job of telling how to do event driven. Use a Swing Timer to make your animation loop, it will get rid of your wasted overhead of trying to control your application instead of letting Java do what it was made to do.

Swing Timers also run in a single thread so you don't have overhead eaten up with multiple timers.

I've literally had thousands of objects on a screen and not consumed the resources you are asking about.

[Phil Freihofner]

I agree with the advice to make things more event driven. But I think the util.Timer is usually a better bet for games than the Swing.Timer. It is true that you need to be more careful with interacting with Swing components, but this can often be handled by posting code on the EDT directly when necessary. Too much activity on the EDT really slows down performance--it quickly becomes a significant bottleneck.

In "Killer Game Programming" there are some test cases with the game loop timing being provided via a util.Timer vs a Swing.Timer, and the util.Timer ended up with much better performance, pretty much identical in performance to the fastest game loop structure that the book described and preferred.

Even easier to code, though, is the AnimationTimer in JavaFX! It runs at 60fps as a default.

Instead of BufferedImages, you would be using WritableImages. There is no need for either repaints or paint() methods or dealing Graphics2D and things like opacity are a simple property setting. There is a tutorial over at JavaGaming.org if you want a quick intro to JavaFX game loops. I've started converting a game I starting with Java2D to JavaFX and am really pleased with how much easier and cleaner the JavaFX code is. And, it integrates well with functional programming constructs that have been added in Java 8.