[Solved] Dellta time issues

Newbie & Debugging Questions
#1

Hey guys,

tl;dr: delta time change returning 0, based off System.nanoTime()

So recently I’ve been dabbling in creating a large voxel engine based game however i had my game running nicely for testing added features and what not however my clock timer randomly stopped working, and i cannot figure it out for the life of me.

Here is my main issue when i run to get delta in the game for movement gravity etc i call the getDt() method and use that for delta and at the beginning of my game loop i call the updateTimeChange() method however the delta returns 0 for every cycle.

Any pointers on how to correct this?

public class Clock {

private static float time;
private static float lastTime;
private static float dt;

public void updateTimeChange(){
	 time = System.nanoTime();
	 dt = (time - lastTime)/ 1000000;
	 lastTime = time;
}
public float getDt(){
	return dt;
}
public Clock(){
	lastTime=System.nanoTime();
}

}

#2

You need to use long instead of float

#3

I changed them to long, but the error still occurs, this one has me stumped.

#4

Did you change the return type of getDt to long also?

#5 
dt = (time - lastTime)/ 1000000;

You’re truncating to millisecond accuracy.
If your update took less than 1ms, ‘dt’ will hold zero.

dt = (time - lastTime)/ 1000000.0f;
#6

… also i would recommend using doubles instead of floats.

it might help avoiding future delta-time-issues. :wink:

#7

There’s no compounding of errors. Doubles don’t help. Better is to skip on the divide and FP and just use raw nano info intead.

#8

Corrected the issue by initializing the variables and changing to double.