Loading .babylon scene as a child of a specific scene graph node

[bghgary]

@trusktr

But what if the meshes all have parents because parent nodes were used to transform the meshes in the modeling program from which GLTF was exported? (third time asking this question here)

I had to read this maybe a dozen times before understanding the question. I think the confusion is caused by the fact that transformNode was introduced later. See below.

@trusktr

Automatically connecting loaded assets into a scene seems unnecessary, which is why I didn’t want to use Load or Append, plus they don’t give me back my specific assets anyway, making it unusable if I want to manipulate the asset without relying on a hack such as certain types have __root__-named nodes.

I didn’t suggest using Load or Append. They will not return information about the asset. These functions are intended to load into a new/existing scene.

@trusktr

I didn’t want to use ImportMeshes because based on the API the .meshes property does not include non-meshes (unless the concept of a “mesh” is convoluted in Babylon?). I need the whole imported tree, up to the top-level non-mesh root nodes.

I’ll admit that when I first looked at the Babylon naming/structure, it was not what I expected. I wouldn’t call it convoluted though. A mesh in Babylon derives from a transformNode which derives from node. transformNode was added later and didn’t exist originally. You are correct in that the list of meshes does not include non-meshes (i.e., transformNodes, lights, cameras, etc). For glTF, the top-level root node is always the first mesh in the meshes array, which is actually an empty mesh (i.e., a mesh with no geometry) and not a transformNode due to backwards compatibility. This can be used to traverse the entire tree.

@trusktr

That leaves only LoadAssetContainer which seemed to be the needed API: it returns the asset and nothing more, with no new scene, and without attaching to an existing scene, and gives me .rootNodes not just .meshes.

Why is it that in my example, attaching rootNodes to a transform node does not work?

I’m not sure who added rootNodes but it’s not populated by the loaders and is always empty unless instantiateModelsToScene is called. @RaananW/@carolhmj Can you take a look?

@trusktr

Here’s my example again, but in your format, and the model does not render:

Here is a working version: https://playground.babylonjs.com/#8FHM4P#4. I would expect rootNodes to work, but it isn’t currently populated. addAllToScene or equivalent needs to be called in order for the scene to know about the nodes.

@trusktr

Do you have a deprecation cycle?

I’ll let @RaananW answer this one.

@trusktr

It can be so much simpler in Babylon.

I agree it can be simpler to use for some scenarios. As I said earlier, I have wanted to investigate making changes to the API, but we have to maintain backwards compatibility. Contributes welcome if you want to help.