Ways to limit Phaser3 update rate?

Question

In my Phaser3 game there is a global gameTick variable that is incremented every update. I am using this to spawn in enemies in my game every 100th update.

Here is a simplifed example of what is going on in my scene class:

update () {
    global.gameTick++;

    if (global.gameTick % 100 === 0) {
        this.spawnAlien();
    }
}

This works fine but as soon as a user plays the game on a monitor with a refresh rate >60hz the update timing breaks and causes the aliens to spawn more frequently.

I have checked this.physics.world.fps and it is 60. I can also modify this.physics.world.timescale but then I would have to do a giant switch statement for every refresh rate.

Either I am missing an obvious solution or my global.gameTick method is not an effective way to accomplish this task.

This is what I have in my config so far

let config = {
    type: Phaser.AUTO,
    backgroundColor: "#000",
    scale: {
        parent: "game",
        mode: Phaser.Scale.FIT,
        width: 1900,
        height: 600,
    },
    physics: {
        default: "arcade",
        arcade: {
            debug: true,
            fps: 60 // doesn't fix update frequency
        },
        fps: { // not sure if this is even doing anything
            max: 60,
            min: 20,
            target: 60,
        }
    },
    pixelArt: true,
};

exciteabletom exciteabletom · Accepted Answer · 2020-01-06T16:30:51

My original post was entirely incorrect. this.physics.world.setFPS() only limits the update rate for the physics simulation.

To actually limit the update rate, use the following method.

// The time and delta variables are passed to `update()` by Phaser
update(time, delta) {
    this.frameTime += delta

    if (this.frameTime > 16.5) {  
        this.frameTime = 0;
        g.gameTick++;
        // Code that relies on a consistent 60hz update
    }
}

This accumulates the miiliseconds between the last frame and the current frame. It only runs the update() code if there has been 16.5ms of delay.

The example above works for 60fps, but if you want to limit the FPS to a different value use the formula: delay = 1000/fps.

Original Post:

The FPS settings in the config seems to be bugged as of v3.21.0.

All I had to do was use this.physics.world.setFPS(60); from my scene class. This limited the update rate perfectly and I am having no issues.

Ways to limit Phaser3 update rate?

1 Answers