GLTF Animation Importing

[ghost]

This adds importing GLTF animations to Unity. I tested it with the GLTF Samples and they all seemed to work with the exception of the WalkingLady. (Not sure why that one isn't working, but it seemed a clear exception.)

[stevenvergenz]

Hi Will, sorry for the long delay in getting back to you. We're very interested in this PR, thanks for submitting it! We're still working on reviewing it as it's a pretty complicated piece of functionality. Plus there's a fairly large reorganization PR coming down the pipe, and we need to figure out if this should be merged before or after.

A question though: Unity animation clips require a "root" node, and all channels point to relative paths from there, but glTF animations have no such concept. How did you choose what GameObject should contain the Animation component? Does it work for glTFs with multiple scenes?

We're working to update our tests with animations to put this PR through its paces now, hopefully we'll have more questions for you once that's done.

Cheers,

EDIT: And a follow-on to the above question, how did you generate deterministic relative paths from the glTF scene? I'm guessing using the node index value?

[donmccurdy]

The walking lady model is broken (KhronosGroup/glTF-Sample-Models#83), no need to worry about that one.

[ghost]

@stevenvergenz Will left on vacation for three weeks this afternoon so it may be a little bit before we get you answers to your questions. I'll ask a couple other Pluton's who might have worked with him on this stuff to see if they know and update if I find out anything.

[bjornbytes]

The Animation component is added to the root node and we generate unique paths from there based on node/primitive index.

[stevenvergenz]

@bjornbytes What is the "root node" in your explanation? Is it the scene or the nearest common ancestor of channel targets?

[bjornbytes]

It's the scene root, we didn't get around to doing to nearest common ancestor approach.

[stevenvergenz]

@willswannackpluto, you back from vacation? Thought you should know that there was a fairly major architecture change pushed a couple weeks back. It would be great if you could update this PR from master, and get things lined up again. That would make it easier to review too. We really appreciate this, animation is fairly high on the priority list, but manpower is always lacking.

[ghost]

@stevenvergenz Yes I am back! Thanks for the update. I saw the huge architecture change and it looks exciting. We're interested in updating the current PR but aren't yet sure when we'll have time to do it. I will post back when we either know we can't work on it or when we know when we'll start working on it.

[stevenvergenz]

@willswannackpluto I got a notification that you added commits to this PR, but don't see them here. I'm guessing it was accidental, and was reverted?

[ghost]

@stevenvergenz Yes it was accidental so I reverted them.

[ghost]

We are at the moment not planning on merging this PR because we don't believe we'll have time to do so for quite a while (a couple months at minimum). I think we should probably close this PR. We can open a new one if we get time and animations still aren't in.