Weird behaviour until component is remounted [minimal reproduction inside]

[AlaricBaraou]

Hello everyone, I have a minimal scene in which the camera follow an object.
Everything is junky until I manually remount the component that manage the camera position.
Here is the codesandbox that reproduce the issue. https://codesandbox.io/s/basic-demo-forked-803j66?file=/src/Camera.jsx
To reproduce :

1. Open sandbox, see that the box is junky
2. Edit the Camera.jsx file ( e.g. add a random comment ) then save
3. This trigger a remount of the Camera component and everything works as I would have expected it to works from the start.

Video of the above.
https://user-images.githubusercontent.com/7174039/159330460-248e76de-955b-42b2-b967-26e892011e88.mp4

Any idea what is causing this ?
Thanks for the help !

[AlaricBaraou]

After discussing it with @SteveSDaBest on the pmndrs Discord it looks like it comes from the renderPriority changing on remount.

If I render in App.jsx
https://codesandbox.io/s/basic-demo-forked-gqc3lr?file=/src/Camera.jsx
vs rendering in camera.jsx
https://codesandbox.io/s/basic-demo-forked-jtgdj2?file=/src/Camera.jsx

I guess that's everything there is to it.

[StevenStavrakis]

For anyone looking for the simplest resolution, it is to use the negative indices feature on render loops to ensure correct order: https://docs.pmnd.rs/react-three-fiber/API/hooks#negative-indices

Though what the correct order is is still unclear.

[AlaricBaraou]

I unmarked it as answered as it feels like there is still something unexplained here.
More opinions on this are welcome

[AlaricBaraou]

Opened an issue about the negative indices as it seems to behave differently than in the documentation #2139

[drcmda]

box -2 and cam -1 works work me. i think this was a framerate sync issue.

the order is determined like so:

subscribers: [...internal.subscribers, { ref, priority }].sort((a, b) => a.priority - b.priority),

[AlaricBaraou]

Yes it also works for me after changing the priority. And I think the jittering is normal when the order is reversed.

By looking at the sort function you shared, I'm pretty sure the doc is wrong then for negative indices. I opened an issue yesterday
#2139

[drcmda]

could you make a quick pr for correctly spelling it out. i have a hard time visualising ordered numbers, it's probably the other way round.

[AlaricBaraou]

Sure, I'll do that today

[AlaricBaraou]

Couldn't find time to do it earlier, I see @CodyJasonBennett took care of it ( thanks a lot 🙌 )
The rest of the discussion is happening here #2139 (comment)

Edit, marking this as answer, but the whole thread is an answer.