CODEWITHSUNDEEP
javaloops
BobTheSatan
BobTheSatan

Reputation: 325

My java game runs in slow motion on different computers

I am developing a game, and just wanted to test it on a different computer to check if the resolutions are ok and all that stuff but noticed one big problem, the game runs in slow motion for some reason... Not laggy, but slow motion.. My game loop is a temporary:

while(gameisRunnin){
     doStuff();
     Thread.sleep(1000/60);

But after the test, I've tried to check how much time does it take to do the doStuff(); code and I tested it like this:

while(gameisRunnin){
     long startT = System.currentTimeMillis();
     doStuff();
     long stopT = System.currentTimeMillis();
     System.out.println(stopT-startT);
     Thread.sleep(1000/60);

The result it gives me is 0, on both computers, (On the one I am developing the game which runs in the perfect speed, and on the pc that it runs in slow motion.. Also I tested it with nano time, it gives me like 50000-80000 on both computes too (pretty much same result. Seriously what's up? Could a superman save me?

UPDATE: Ok so when I run the game on the other computer NOT on full screen, it's runs fine, but when it is on full screen, it's slowmotion Update: Looks like I am the superhero here, I've set the displaymode the refresh rate to unknown, I guess that was the whole problem...

Upvotes: 3

Views: 1923

Answers (3)

BobTheSatan
BobTheSatan

Reputation: 325

The answer is that the refresh rate of the game wasn't supported by the monitor, changing the refresh-rate from 60 to DisplayMode.REFRESH_RATE_UNKNOWN fixes the slowmotion problem.

Upvotes: 1

tzima
tzima

Reputation: 1295

You've to use something what is usually called "delta time". Basically it means, that you measure how long it takes to do one iteration of the game loop and then use this number for all the movements.

This is because of the different count of FPS on different computers. Instead of moving objects for just constant amount of pixels, you're defining speed and calculating the actual size of movement dynamically.

Short example:

public void gameLoop() {
    long initialTime = System.nanoTime();

    game.redraw();
    game.update(System.nanoTime() - initialTime);
}

// inside the class Game
public void update(long deltaTime) {
    someObject.moveToRight(deltaTime * speed);
}

Upvotes: 2

Troubleshoot
Troubleshoot

Reputation: 1846

Read this article: click here

Also, as a side note, use System.nanoTime() because System.getTimeMillis() isn't as accurate.

Upvotes: 0

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