Broken blender export with animation (demos and blends are provided)

[rnixik]

Description of the problem

PR #8412 updated blender export and now there are no way to export mesh with skinned animation.
I have tested with women model and with monster model, which is imported from collada examples/models/collada/monster/monster.dae. I have build demos with the same main.js but with different json files.

Demos

Settings for mesh export (Scene is unchecked, using THREE.JSONLoader):

Only mesh with new export - women (4MB)

Only mesh with old export - women (4MB)

Only mesh with new export - monster (242KB)

There is another option and another problem: export with checked "Scene" and using THREE.ObjectLoader:

But with this option animation does not work correctly in both versions:

Scene with new export - monster (285KB)
Scene with old export - monster (284KB)

I have worked with old exporter and noticed that vertices values in json are bigger with Scene checked then with unchecked version. I have tried to replace this array in json file and animation becomes work properly. I can not figure out what is the problem with exporter with checked Scene.

Files

• Demos with json (8.26MB)
• monster.blend + textures (692KB) (or just import monster.dae from examples)
• women.blend + textures (10.4MB)
• Full (19.4MB)

Exports have been done with reset transforms of bones before each export.

Three.js version

• Dev
• r75

Browser

• Chrome
• Firefox

[tschw]

@rnixik

Which Three.js release is the "old" exporter?

[... Scene checked ... ] But with this option animation does not work correctly in both versions

I think this part is a known issue.

I have tried to replace this array in json file and animation becomes work properly

Replaced with ...?
The array exported by the old or the current exporter?

[rnixik]

@tschw

Which Three.js release is the "old" exporter?

Old exporter is before PR #8412, it means r75, new is in dev.

Replaced with ...

Array of vertices in scene.json replaced with array of vertices from object.json (the same mesh).

The array exported by the old or the current exporter?

I've experimented with old exporter.

[rnixik]

A little more about replacing.

1. I exported monster with unchecked Scene and got monster.json with these vertices:
   
2. Then I exported monster with checked Scene and got monster_scene.json with these vertices:
   
3. Then I copied vertices from the first and put them into the second and got monster_scene_replaced.json with these vertices:
   

Now I got correct animation, but with a little different scale of object.
Demo with THREE.ObjectLoader and animation after replacement.

Files:
replacing.zip (347KB)

[tschw]

@rnixik

Old exporter is before PR #8412, it means r75, new is in dev.

Since you already identified the breaking PR, let's first see whether the author is around, to save us some digging.
/ping @phfatmonkey

If not around, we'll do exactly that.

Now I got correct animation, but with a little different scale of object.

Seems it should be able to make this one work too, then.

[phfatmonkey]

Hey guys. I did some work on the skinned mesh export recently because we couldn't get any skinned meshes to work at all.

Is your skinned mesh scaled in Blender? If so, try Applying the Transformations of both Rotation and Scale. That usually fixes the "nightmare dragon" problem (that's what we call it when the mesh distorts like that.

[tschw]

@rnixik
Did the suggestion above solve your problems?

@phfatmonkey
Please correct me if I'm wrong, but your PR seems to have broken it - at least in OP's case. Is there any way to get rid of the quirk?

[rnixik]

Is your skinned mesh scaled in Blender? If so, try Applying the Transformations of both Rotation and Scale.

Applied, but does not help. Tested with scene and without scene

[phfatmonkey]

@rnixik Are you exporting the model when the mesh is in the bind pose? If not, add an action with just one keyframe where all the bones are in their default position (cleared transform).

Please correct me if I'm wrong, but your PR seems to have broken it - at least in OP's case. Is there any way to get rid of the quirk?

@tschw With the new THREE, we weren't able to get any skinned meshes loaded properly at all when using the last version of the exporter (r73). The PR I did got us to a point where we can export and display skinned meshes as expected.

I'll take a look at your scene and examples and see if I can identify the issue.

[rnixik]

@phfatmonkey Yes, in the bind pose

[tschw]

@phfatmonkey

With the new THREE, we weren't able to get any skinned meshes loaded properly at all when using the last version of the exporter (r73). The PR I did got us to a point where we can export and display skinned meshes as expected.

You said so in your previous post. Else reverting the changes until the issues are resolved would have been a short-termed solution, but I figured that it would probably break the export in a dozen of other cases.

I'll take a look at your scene and examples and see if I can identify the issue.

Thanks a lot!
That's what I had hoped for.

If not, add an action with just one keyframe where all the bones are in their default position (cleared transform).

It'd be super awesome if we could automate these steps somehow. I don't think we should settle with having a secret science of model export.

[phfatmonkey]

Ok, I looked at your files and here's what I found.

The Armature and the Mesh in both scenes (women.blend and monster.blend) have scale applied. It's easy to fix the mesh, but applying transforms on the Armature causes the mesh to be horribly distorted. As a general rule, make sure you don't scale or rotate your rig or bones. It's just a good best practice for rigging in general to do this.

Now, on to the exporter issues...

I'm fairly certain this issue existed before my pull request. I just tried r75 with the newest marine model included in pull request #8410 and I got this:

Similar results with the exporter on the dev branch just before my PR:

Then I tried the newest dev exporter with my change:

After r69 the exporter was completely changed and the way it's grabbing vert transforms is a little different. Previously transforms seemed to be using world space, but now they're transformed using a matrix. Perhaps when a model or armature is scaled the transform matrix doesn't take that into account, and since skinned verts need the bone transforms to be transformed correctly, it might explain the results. Maybe ping @repsac, one of the original authors, to see if he has any thoughts.

It'd be super awesome if we could automate these steps somehow. I don't think we should settle with having a secret science of model export.

Agreed. I suspect that's what the 'Rest' option was for in the previous exporter. However, that wasn't working either so I removed it until that feature can be added.

@rnixik I'm still curious to know which version of the exporter was used to get accurate results. Were you using the JSONLoader? With the newest exporter we were able to use the newest THREE with the ObjectLoader for skinned meshes. I agree it still needs some work, but it was unusable before.

[rnixik]

Ok. I will play with marine model.

I'm still curious to know which version of the exporter was used to get accurate results. Were you using the JSONLoader?

THREE.JSONLoader + exporter from r74 (I guess it has not changed in r75)

[phfatmonkey]

THREE.JSONLoader + exporter from r74 (I guess it has not changed in r75)

From what I understand, The JSONLoader is deprecated. If you still want to use it you'll have to use an older exporter.

[rnixik]

The JSONLoader is deprecated

What I should use instead? Even ObjectLoader depends on JSONLoader: https://github.com/mrdoob/three.js/blob/dev/src/loaders/ObjectLoader.js#L84

[rnixik]

I have tried marine model. It works fine with new exporter with scene checked and THREE.ObjectLoader. But can't even find the model on the scene with scene unchecked and THREE.JSONLoader (no any errors; tried different scale, camera positions, different materials, fov, orbit controls, new exporter, old exporter).