The initial direction of GLB model import is wrong

[CrimsonYao]

Describe the bug Hello, I just started using Gltfast. Gltfast is very useful. I like it very much, but I still have some problems because of my ability. I want to ask for advice.

When I import the model with Gltfast, I find that the initial orientation of the model is always behind the Z axis (0,0, -1), whether it is editor or runtime.

So it's very inconvenient for me to operate the model in the game. I want to ask what configuration can make the direction of the model conform to the front of the Z axis (0, 0,1)?

GLB file export The GLB model was exported from Unity using UniGltf ver2.28.0.

To Reproduce Steps to reproduce the behavior:

1. Export GLB model from Unity using UniGltf
2. Drag GLB model to Unity
3. Gltfast Import GLB model
4. See that the initial direction of GLB model is wrong

Expected behavior The orientation of the model should be the front of the Z axis (0, 0,1)

Screenshots

Desktop (please complete the following information): glTFast version 4.8.3 Unity Editor version 2020.3.24f1c2 Render Pipeline and version HDRP 10.7.0 Platform: Win64_86 build (running on a 64x machine) as well as in Win64 editor.

additionally (if significant for the bug):

• Device: GTX 3060
• OS: Win10

[hybridherbst]

Are you sure this isn't a bug in export from UniGltf? glTFast (and dev UnityGltf, for that matter) properly respect orientations on import and export for quite a while.

[atteneder]

I'm also quite confident that this not a bug on glTFast side, but rather an inconsistency with UniGltf.

Historical background: Up until version 3.x, glTFast used to convert models from glTF's to Unity's coordinate system in a different way. See Coordinate System Conversion Change.

As you can see, at first I tried to keep X and Y axis aligned (and flip the Z axis). There's nothing wrong with it, expect glTF defines positive Z as forward (just like Unity) and thus many users had the same problem you have: models face the wrong way.

That's what convinced me to change the conversion (keep Y and Z axis and flip X). As @hybridherbst mentioned, this is consistent with many other importers and I see it as the correct way.

I recommend filing an issue with UniGltf.

Thanks

[CrimsonYao]

I'm also quite confident that this not a bug on glTFast side, but rather an inconsistency with UniGltf.

Historical background: Up until version 3.x, glTFast used to convert models from glTF's to Unity's coordinate system in a different way. See Coordinate System Conversion Change.

As you can see, at first I tried to keep X and Y axis aligned (and flip the Z axis). There's nothing wrong with it, expect glTF defines positive Z as forward (just like Unity) and thus many users had the same problem you have: models face the wrong way.

That's what convinced me to change the conversion (keep Y and Z axis and flip X). As @hybridherbst mentioned, this is consistent with many other importers and I see it as the correct way.

I recommend filing an issue with UniGltf.

Thanks

OK, I understand. Thank you very much for your reply!