Strange behavior when dev console is open - Firefox is fine

Questions
1

Hi All,

I’m trying to implement a ‘cursor precise drag on arcRotateCamera’ at any zoom/radius level . I don’t think this feature exists yet ?

https://playground.babylonjs.com/#SRZRWV#2111

Here is a playground with a very basic implementation. A small sphere appears on the big one under the position you drag.

My bug : go to lower or upper beta camera limit. Mouse up, then mouse down on try do drag up or down. Depends the beta limit you are.

My ‘problem’ appears only when chrome/edge dev console is OPEN. Firefox seems bug free.

When dev console is closed, you can drag smoothly the small sphere on the big one.

When dev console is opened, the drag is weird and jittering. The small sphere does not follow the curor.

Can you confirm ? Any idea what’s happen here , when dev console is open ?

I’ve tested on 2 pc / windows

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2

Yes, I do have the same bug on Linux as well. Very strange :thinking:
At first i thought it was due to the resize or change in window structure, but even when undocking the debug console to another window, it persists until you close the debug window.

I don’t know, but my guess is that when you open the debugger, the JS is in another state (since you can record performance, pause the execution, go step by step in the instructions of the JS event loop, etc, etc…). But I agree it’s quite weird

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3

If you drag really slowly, you can make the marker jump way off the current mouse pos. It is getting worse, the closer you are to the pole.

This seems like awfully specific. I mean the dev tools thing is weird. But I would write a couple of unit tests against pointToSphericalCoord().

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4

@Tricotou & @Joe_Kerr.

Thanks for your answers ! I continue investigating.

5

[edit] this is not solved

This is solved on my side (works with dev console on) : https://playground.babylonjs.com/#TH1G23

I was setting camera.alpha and camera.beta directly. The fixed solution used now camera.inertialAlphaOffset &Beta… (I suppose the correct way to do it)

However, I have no idea about the dev console bug.

[edit] by using inertialAlphaOffset&inertialBetaOffset I loose the pixel perfect drag precision

6

My guess? It’s a performance issue after running the playground many many times.

You are not clearing the window event listener, so every time you run it you:

  1. keep a reference to the old engine
  2. running resize on ALL engines
  3. console.logging - “resize”

My guess is that if you refresh the page it goes away, until you run the PG a few more times.

The easiest method would be to use the scene.onDisposeObservable to clear the event listener. Or just depend on the engine resize we already have implemented (part of the engine initialization for every playground)

7

Hey @RaananW, I’m not sure it’s about cleaning event Listener, on the first referenced playground in this post, if you switch on / off the console with f12, you can see that the weird behavior does not exist when dev console if off, and appeared when console is on. You can refresh how many times you want, the scene works when console is off.
I suspect more the way I wrote the CameraEarthCustomControl class.

8

@RaananW, using this.camera.rebuildAnglesAndRadius() ; every pointerMoveEvent seems to fix the weird drag behavior when dev console is open.
https://playground.babylonjs.com/#SRZRWV#2121

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9

I investigated a bit more. I’m not monomaniacal ! :roll_eyes:

I isolate a bit more the bug when dev-console is open fixed by using camera.rebuildAnglesAndRadius() .

In fact you only have to check upper and lower beta limit on every pointerMoveEvent.
With out this fix , and console open, if you look at camera beta when dragging from a pole : it alternates between the upper/lower betalimit (depends the pole you are) and the camerabeta under cursor (the jittering pb).

Last note, it must be really dev console specific … I’ve just try on chrome console to record performance (without the fix), and you know what, the bug disapear… :thinking:

https://playground.babylonjs.com/#SRZRWV#2122 → uncomment line 92-97 to apply the fix

10

Not sure if I found something relevant. But see here:

It seems like I can replicate the jumpiness this way - even in Firefox and w/o DevTools. The difference is though, now, it gets worse the further you are away from the pole.

So if DevTools is open does it somehow mess with the frame rate? But then again, we would see something in the fps counter, wouldnt we?

11

true ! setting engine.maxFPS imitate well the open dev-console bug.

If you look at camera.beta when dragging, it alternate between 0.8 (lower beta limit) and a camera.beta corresponding to the dragging cursor position. The checklimits code if enable still fix the scene…

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