Can someone help me figure out why the rotation Y Angle of my gltf files exported from blender is always 180

This is the information displayed in inspector

This is the export option for blender

Or give me some documentation or a link that just makes me understand why

That’s because Blender is right-handed system while BJS is left-handed system by default.


If you want to get rid of this transformation, you can set scene.useRightHandedSystem = true just after the scene is created.

The reason I ask this question is that when I call the MergeMesh function to merge, the merged building mesh disappears, but its surrounding box is visible. So I’m trying to figure out what went wrong, because I used the same mesh in my other simplified example and it showed up fine.

Can we eliminate this problem if we change to a right-handed coordinate system? I’ll change it to a right-handed coordinate system if I have to

I’ve reproduced this problem in the Lite instance, and I’ll upload a palyground later @Evgeni_Popov

@Evgeni_Popov I created a palyground that replicates this problem

The reason it appears to disappear is that the origin position is outside the frustum.

This is weird, because its origin position in Blender is in the center of the world.

What you see is the thin instance you cloned, and if you pull the camera back to 0,0,0 you will see the source mesh you merged. The problem that thin instances disappear may be related to how instance objects are rendered.

Can you save this playground of yours? After I modified the parameters, I didn’t see the effect you said. Are you Chinese?

Blender gltf MergedMesh ThinInstance | Babylon.js Playground (
I swapped the thin instance for a normal one, and octree seems to have a problem with using it with thin instance.

This is a step back solution, and if I can’t solve the thin instance problem, I’ll replace it with normal instance.

Blender gltf MergedMesh ThinInstance | Babylon.js Playground (
It seems that only the source grid is not displayed (which may be a feature of the thin instance itself), and it was wrong to say that using octree would cause problems.

This is obviously not octree problem, because when I delete it, the problem is still there.