Disable animation track optimizer by default

[TokageItLab]

The current animation track optimizer works well for very simple animations, but does a bad work for most humanoid 3D model animations. In fact, a lot of the same issues have been posted.

It is not good to have the default settings that make the animation corrupt. Compression should be set according to the user's needs, and They should probably be disabled by default.

Fixed #53864
Fixed #58968
Fixed #59150

[Calinou]

Fixed #49974

The issue was reported in 3.x, not 4.0. Therefore, that issue is only resolved if this is cherry-picked for 3.6.

[fire]

We have multiple options to optimize space usage of animation.

1. Uncompressed
2. animation track optimizer corrupts the animation
3. bitpacking compression cannot be modified
4. reducing the frame rate corrupts the animation

Choosing uncompressed animations means out of the box animation keyframe takes storage.

Perhaps we can develop other options like force bitpack on export similar to tscn export scn.

I do prefer correct animations that doesn't require quality checks. So either uncompressed or bitpacked at export can work.

@reduz any advice on this?

[TokageItLab]

I changed some of the importer process in #63138 to adapt retargeting to bitpacking. So it's fine to make bitpacking the default if #63138 is approved.

[reduz]

Some concerns.

• I think what the optimizer does is fine, at much it needs to be tweaked to be less aggressive or the algorithm improved.
• Bitpacking is more expensive CPU wise, should not be used by default.
• If you use cubic interpolation, the optimizer will not work properly, so it must be disabled by default. Cubic is only really good if all keys are imported.

So to me the path forward here would be to simply improve the compression code. The last time I took a look at it, I did not find the algorithm to be fantastic, so it can definitely be improved.

[reduz]

To explain a bit better, I understand this can be over optimize complex animations leading to a reduction of quality. I think this is definitely unwanted.

But on the other hand, removing repeating unchanged or mostly unchanged keys is also very important. Animations are full of tracks with keys where nothing changes, so the optimizer has to run by default.

I suggest we discuss how to improve it or at least change the defaults so it does not break perfectly good animations.

[TokageItLab]

I agree, as explained in the contributors chat, the current optimizer seems to lack the "key velocity" factor.

[TokageItLab]

I will send a proposal to improve the optimizer later.