Java 2D Game drawing performance

Question

I created a 2D game in java and am trying to get it to 60 fps with a resolution of 1920x1080 pixels. My game logic is performing fine in less than 1 millisecond. But the drawing takes up to over 10 milliseconds. This might be sufficient on my rather strong desktop (intel i5-4670K @ 3.40 Ghz), but on my laptop (intel i5-6300HQ @2.30 Ghz) the game is already slowing down quite a bit. The drawing is separated into two main steps:

draw every component of the game onto a BufferedImage
draw the BufferedImage in my extended JPanel class

The corresponding code is this:

@Override
public void run() {

    init();

    long startTime;
    long elapsedTime;
    long waitTime;

    while(running) {

        startTime = System.nanoTime();

        update();
        long updateTime = (System.nanoTime() - startTime) / 1000000;
        draw();
        long drawTime = (System.nanoTime() - startTime) / 1000000;
        drawToScreen();
        long drawscreenTime = (System.nanoTime() - startTime) / 1000000;

        elapsedTime = System.nanoTime() - startTime;
        waitTime = targetTime - elapsedTime / 1000000;
        if(waitTime < 0) {
            waitTime = 0;
        }

        try {
            Thread.sleep(waitTime);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

public void init() {

    GraphicsEnvironment env = GraphicsEnvironment.getLocalGraphicsEnvironment();
    GraphicsDevice device = env.getDefaultScreenDevice();
    GraphicsConfiguration config = device.getDefaultConfiguration();
    image = config.createCompatibleImage(1920, 1080, Transparency.TRANSLUCENT);

    g2d = (Graphics2D) image.getGraphics();
    running = true;
    gsm = new GameStateManager(this);
}

public void update() {
    gsm.update();
    Keys.update();
}

public void draw() {
    gsm.draw(g2d);
}

public void drawToScreen() {
    Graphics g = getGraphics();
    g.drawImage(image, 0, startDrawY, scaledWidth, scaledHeight, null);
    g.dispose();
}

Both the draw and drawToScreen methods take up to 5 milliseconds. inside the draw method, the slowest parts are drawing the background image (1920x1080 image) and drawing the level (consisting of several 135x135 images), which both take a few milliseconds.

Now i have two questions: Is this draw-speed normal for large images like that? And if not what might I be doing wrong here or how can I improve the drawing-performance?

Graphics2D extemds Graphics. You're saving Graphics2D in init(). Why not use the g2d instead of creating another Graphics in drawToScreen()? — Dakoda, Jul 31 '17 at 15:00
If you're looking to build a 2D game that renders efficiently, you should look into libraries such as libGDX (or anything else that extends the java OpenGL implementation (LWJGL)). OpenGL uses an efficient graphics pipeline to render in 2D and 3D — Kylon Tyner, Jul 31 '17 at 15:05

score 2 · Accepted Answer · answered Jul 31 '17 at 15:26

Java's core libraries are not meant for efficient graphics rendering, rather user interfaces. JavaFX supports hardware acceleration. If you require fine tuning of graphics, see LWJGL or LibGDX. LibGDX has higher level abstractions, whereas LWJGL has bindings directly to the OpenGL, OpenGLES, and Vulkan API.

If you do not want to use these libraries, Java can have hardware acceleration enabled. As far as I know, it is not enabled by default. You will need to add the following argument to the JVM:

-Dsun.java2d.opengl=true

If you are just rendering an image, it will be fine to continue using a BufferedImage. However, if you are editing the image frequently, consider looking at using a VolatileImage instead.

This is about the extent of my knowledge on speeding up Java2D games. I would recommend looking at this question here. The answerer seems very knowledgable, and goes more in depth than I do on the same topic.

Thank you for your answer. I'm using OpenGL via JOGL now and this is speeding up the drawTime tremendously. It is sometimes even faster than the updateTime. — Aschas, Aug 02 '17 at 10:20

Java 2D Game drawing performance

1 Answers1