Initial zoom is not properly determined from scene bounds

[javagl]

(Not sure whether this is the right place to report this. It might be related to #367 , but refers to non-animated models)

I created different assets that all represent a unit cube. The assets only differ in their "internal structure", i.e. the geometry and transforms of the nodes that the geometry is attached to. But they all end up as a unit cube in (0,0,0)-(1,1,1). These bounds are also properly reported by https://gltf.report/

When dragging and dropping these into the viewer, the initial zoom varies wildly:

The assets from this screen cap are attached here:

someUnitCubes 2025-06-03.zip

[hooir-dev]

Just to share a resource that might be useful for anyone testing GLTF/GLB files — GLTF Tools Viewer
It's a free web-based viewer with drag-and-drop support and real-time rendering, which can help compare behavior across different viewers when troubleshooting issues like this one.

[javagl]

@donmccurdy I don't know where the line between three.js itself and the viewer is drawn - do you know from the tip of your head whether the zoom level is determined here or in three.js itself?

[donmccurdy]

Thanks @javagl! This viewer relies on THREE.Box3#setFromObject from three.js to compute the AABB. After that my viewer decides how to center the object and orient the camera. I suspect the bug here is on the viewer's side, not three.js, but I haven't checked yet to confirm that three.js computes the same AABB for these models.

Computing full bounds on animated scenes would require doing something other than setFromObject, but that wouldn't be the issue here (as you'd mentioned).