Hey I'm creating a "game" or more like a simulatio...

# compose-desktop

[Jan]

Hey I'm creating a "game" or more like a simulation following the example of the Falling Balls Game on github. But my game is kinda "lagging" and it's also fps dependent. The example covers that (I think) but I don't think I'm implementing it right. Currently I have: (thread)

[Jan]

val x = (simX * SCALE) + windowWidth / 2
val y = (simY * SCALE) + windowHeight / 2
//this updates the x and y coordinates.

[Jan]

Here you can see the lag

[Jan]

This is the loop:

LaunchedEffect(Unit) {
        while (true) {
            withFrameNanos {
                if (sim.hasStarted && !sim.isPaused)
                    sim.update(it)
            }
        }
    }

[Jan]

But I'm currently ignoring "it" in the code above

[Landry Norris]

Have you wrapped sim.update in measureTimeMillis to see if that's the bottleneck?

[Jan]

thats giving me 0 or 1

[Landry Norris]

It looks like the update function isn’t causing a bottleneck, then. Have you tried saving the last nanos value to get the exact fps it’s running at?

[Landry Norris]

It looks like you’re trying to run it as fast as possible. Whenever I do something on loop, I usually set up a class that uses coroutines to set up an event loop. It would basically have a suspend function named run or something and would loop, checking if Clock.System.now() is greater than the last time plus a delay, delaying 1ms if it isn’t.

[Landry Norris]

This will even out the fps more than running it as fast as possible.

[Jan]

lemme try this

[Jan]

Like that?

val millis = System.currentTimeMillis()
        if(millis < previousTimeNanos + 1) {
            delay(1)
        }
        previousTimeNanos = millis

it still lags

[Jan]

used ur example but it somehow makes it worse

val nano = Clock.System.now()
        if(nano < previousTimeNano.plus(1.milliseconds)) {
            delay(1)
        }
        previousTimeNano = nano

[Landry Norris]

The while loop should start with if(nano < previousTimeNano.plus(16.milliseconds)) continue, so you are comparing to the last actual frame time.

[Landry Norris]

I generally use if(lastTime.periodUntil(now, TimeZone.UTC).nanoseconds < delay) { delay(1); continue }

[Landry Norris]

After that, set lastTime to now and call your frameTick function

[Jan]

Sorry for bothering you for so long, but like that?

while (true) {
            if(sim.previousTimeNano.periodUntil(Clock.System.now(), TimeZone.UTC).nanoseconds < 16.milliseconds.inWholeNanoseconds) { delay(1); continue }
            sim.previousTimeNano = Clock.System.now()
            if (sim.hasStarted)
                sim.update(scrollState)
        }

[Landry Norris]

That looks fine. I personally would set now to a variable once so it will be the same in both places (affects how framerate works when your frame tick takes time).