FreeCamera doesn't work properly with deterministicLockstep in Playground

I still can rotate camera but movements with arrow keys don’t work.
When not in the playground it works okay, but I am using relatively old version locally. So, it might be not relevant.

Here is example from doc: Doc link. FreeCamera in the playground example doesn’t work.

@PolygonalSun, could this be a regression ?

It was already the case in 4.2 but it seems strange indeed :frowning: maybe @Cedric or @RaananW would know as well ?

Based on what I’m seeing, it looks like the value for engine._deltaTime is getting stuck at 0 so whenever the speed for keyboard movement is calculated, it ends up being 0 and no movement is made. I’m not sure why this is happening yet but something isn’t letting that value get updated to a non-zero value.

Maybe @Cedric can provide us tips on how what value to use in deterministic lock step mode ?

No particular tips here but figuring out why deltaTime is 0.

Thanks man, for the time being I’m going to assign this to you while you investigate this and when you find something, just assign it back to me.

I can’t repro on my side. I’ve added

deterministicLockstep: true,
  lockstepMaxSteps: 4,

in the options at engine creation but the freecamera is still working with arrow keys.
How did you repro @PolygonalSun ?

I just repro’d it by trying out the PG at the end of the deterministic lockstep section linked above: Deterministic lockstep sample | Babylon.js Playground (


render loop is not running on the new engine created in the PG. So, no beginFrame called and the deltaTime is not computed.


will trigger the _deltaTime computation and arrow keys will work.


Makes sense. Thus, it’s a documentation issue, not the BabylonJS issue itself. Thank you.