Replace ColladaLoader with ColladaLoader2

[Mugen87]

This PR removes the old ColladaLoader and replaces it with ColladaLoader2.

ColladaLoader2 supports the most important features in a much more efficient way. It uses BufferGeometry, it directly generates AnimationClip objects for skeletal animation and allocates less memory when parsing a dae file.

However, keyframe animations and morph target animations are not supported anymore. But I personally think the project should not invest more time in enhancing a Collada loader but focus on glTF. So if users are missing features, they can try to convert their files to glTF with COLLADA2GLTF.

If a community member would like to introduce more features to ColladaLoader, I will support as best as I can. Same for bug fixing. But still three.js as a project should generally recommend to use glTF wherever possible.

[looeee]

But still three.js as a project should generally recommend to use glTF wherever possible.

I'd like to agree with you, but as far as I have been able to find there are hardly any glTF exporters, aside from the blender one which is far from easy to use. So 'wherever possible' so far means 'not in most cases'.

I haven't tried the Collada to glTF converter though, if that works well then I like the idea of recommending glTF instead of Collada, specifically. But I don't think it's quite ready to be recommended as the overall preferred format.

[Mugen87]

I haven't tried the Collada to glTF converter though, if that works well then I like the idea of recommending glTF instead of Collada, specifically.

I've tested the converter with some models but it did not always produced correct output (see https://discourse.threejs.org/t/skinned-mesh-distorted-after-converting-to-gltf-from-dae/867). But as long as the developers fix the bugs, i'm okay with it.

[mrdoob]

Thanks thanks!

[mrdoob]

@Mugen87 If you want to make it even more robust, here's a bunch of samples from a previous attempt of re-doing ColladaLoader (sadly it was done in CoffeeScript):

https://github.com/rmx/threejs-collada/tree/master/testdata/3drt-monster

[Mugen87]

Interesting!