Implement and rename hmdEnabled to magicWindowTrackingEnabled

[andreyrd]

Description:
This is an implementation of the fix for #4520

Changes proposed:

• Rename hmdEnabled to magicWindowTrackingEnabled
• Pass through magicWindowTrackingEnabled setting to magicWindowControls.enabled
• Reset magic window eulers when tracking is disabled. Otherwise you can get stuck looking at the ground. This was also what the original code was aiming to do, since previous versions used pitchObject and yawObject for gyroscope tracking. But the previous check oldData && !data.hmdEnabled && !oldData.hmdEnabled should actually have been more like oldData && !data.hmdEnabled && oldData.hmdEnabled in order to catch the transition from enabled to disabled.

[dmarcos]

I think this should be

if (oldData && !data.magicWindowTrackingEnabled && !oldData.magicWindowTrackingEnabled) 
{
...
}

equivalent to old code

[andreyrd]

I think the old code might be wrong.

My intention is that it only resets when the property changes from disabled -> enabled.
With the old check it will only change the second time that update is called with the value disabled.

So it will still work, but on the second update and will reset every update afterwards.

If I go back one more commit in git history of that line, it appears the original intent was closer to what I'm thinking with my change:
https://github.com/aframevr/aframe/blame/e9ba54ebcf724d828fba90fce9adc530e40526d6/src/components/look-controls.js#L45

!hmdEnabled && oldData && hmdEnabled !== oldData.hmdEnabled can be logically reduced to !hmdEnabled && oldData && false !== oldData.hmdEnabled and then to !hmdEnabled && oldData && oldData.hmdEnabled

Commit fe199d changed this: fe199da#diff-6285039eee70ed830f70f7d2f7b7dfa5R47

[andreyrd]

Any thoughts on this? I can change it to be equivalent with the old code, even though I think the logic is wrong. It doesn't affect my use case of it anyway, so doesn't have to be my problem to deal with.

[dmarcos]

Maybe we always want to reset if it value has changed?

if (oldData && data.hmdEnabled !== oldData.hmdEnabled)

[dmarcos]

This is pretty close. What do you think about the comment above?

[andreyrd]

Hey, sorry, have been quite busy lately. That makes sense. I think either way when enabling, the objects will almost immediately get overwritten from motion data, but I think it makes sense to always have a clean state when toggling. Especially since now it's resetting the proper magicWindowAbsoluteEuler, which means you can still set a "starting place" for motion using touch.

[dmarcos]

Thanks! I thinks there's a bug. I left a comment

[dmarcos]

Thanks for the patience. I think we're pretty close to merge this.

[dmarcos]

thanks!