Getting Started with Babylonjs Unity Toolkit

Published Sep 23, 2021

The BabylonJS Unity Toolkit is a toolkit that allows you to export a Unity project as a Babylon Project. It works by exporting your whole scene in the GLTF format and adding metadata.

It can be extremely convenient but it can be a bit hard to get started as the documentation is kinda lacking. Here I share a few things I’ve found out, and will keep adding more as I get more familiar with the topic.

• Short build time
  It takes 10-20 seconds to build your project. This is much faster than Unity for web (which takes several minutes at least). You also avoid all the time wasted by unity recompiling your C# (which is a major pain in more recent versions).

• Only substractive lighting is supported for lightmaps
  This is mentionned here in this video here: https://forum.babylonjs.com/t/require-extension-cvtools-babylon-mesh-is-not-available/17592/9
  This means shadows from static objects will not be applied to moving objects. In Unity this is fixed by using light probes, but I am unsure as to how this is handled in the toolkit but I’ll try out soon.
  The video also shows how to simplify meshes

• The toolkit contains a mesh simplifier
  This is REALLY neat if you’re using modular assets. This is mentionned in the video above: go to the Babylon geometry tools after selecting your object and run the mesh simplifier.

• URP and HDRP shaders are not supported
  They will be replaced by standard shaders, which will break your materials.
  Do yourself a service, and stick to the standard rendering pipeline instead when using this toolkit. Your Unity project will also be a lot more responsive in Editor.

• Materials don’t seem to be readily accessible from Mesh
  I’ve tried to modify the material from a mesh at runtime, but I haven’t managed to access this material from the mesh. Instead, I’ve had to find the material by name from scene.materials.
  I think the way to proceed for this is to toggle “instance meshes” in the unity toolkit and access the “instancedmesh” from your script component, but I haven’t tried it yet.
  I’ve opened an issue as a request for information here: https://github.com/BabylonJS/UnityExporter/issues/36

• Register ScriptComponents on mesh object to access them
  I wanted to access an object’s Controller (a user-created script component) after detecting a mesh by raycasting, but related methods (FindScriptComponent or something similar) either didn’t find anything or required lookup by class name in string, which I thought might be problematic in case of inheritance.
  In this case, I decided to go another way: a script component has access to a transform mesh and, as it turns out, the mesh accessed by raycasting is the transform mesh so we can look up a property by name.
  In my case, I set a “controller” script component as the “controller” property of the mesh and was able to access it through raycasting.

• Exporting mecanim animations is mostly well supported, with exceptions
  I was trying to export Unity chan from the following asset: https://assetstore.unity.com/packages/3d/animations/haon-sd-series-bundle-84992
  The mesh does get exported but some animations seem to be broken, with unity chan being stuck in T-Pose.
  I think the issue is likely due to the model being modular: face is seperated from body etc, so I guess the current workflow for Mecanim export is broken. I guess this could be solved by merging the different parts. There are some skinned mesh mergers on the asset store, but I haven’t tried them yet. I’ve tried a few scripts I’ve found online, but the results were far from great.

That’s all for now, I’m still getting used to the whole thing but I thought the toolkit is great work and is pretty neat. I’ll keep posting things as I figure them out if I think it’s useful to know.