Wrong animation duration/offsets with FBXLoader

[FlorentMasson]

Description of the problem

I have a FBX file with multiple animations created with Maya. The animations are created on a single timeline and exorted with the Game Exporter - that's the only way I found to pack multiple animations in a single file.

The animations are messed up with three .js and the duration is wrong. They work great with Windows 3D Viewer. The reason is when loading, times do not necessarily begin at zero.

At this debug point : https://github.com/mrdoob/three.js/blob/ff48de58e216bc72abb4085a080c5acb66f2f584/examples/jsm/loaders/FBXLoader.js#L2685 Here is the track content :

And the AnimationClip duration is always calculated from offset 0 https://github.com/mrdoob/three.js/blob/cd41804aa436bb2cfd79797c04985f75c4c63e63/src/animation/AnimationClip.js#L403

In relation to https://github.com/mrdoob/three.js/issues/14894 but to me this is not a feature suggestion, it's a bug with the loader. I'm not sure what the exact clean solution should be.

Three.js version

• [ ] Dev
• [X] r120
• [ ] ...

Browser

• [x] All of them
• [ ] Chrome
• [ ] Firefox
• [ ] Internet Explorer

OS

• [x] All of them
• [ ] Windows
• [ ] macOS
• [ ] Linux
• [ ] Android
• [ ] iOS

Hardware Requirements (graphics card, VR Device, ...)

[FlorentMasson]

Adding this

            var minTime = Number.MAX_VALUE;
            tracks.forEach(function (track) {
                minTime = Math.min(track.times[0]);
            });
            tracks.forEach(function (track) {
                for (var i = 0; i < track.times.length; i++) {
                    track.times[i] -= minTime;
                }
            });

before https://github.com/mrdoob/three.js/blob/ff48de58e216bc72abb4085a080c5acb66f2f584/examples/jsm/loaders/FBXLoader.js#L2685 fixes it for me

[looeee]

If I recall the issue was that doing this breaks other files. If you want to create a pull request with your fix I'll double check that and share any models with problems.