Import .fbx - Newly added mesh vertices in newly added Vertex Group (for new bone in already existing armature) all being translated into root bone position in Skinned Mesh Renderer

My problem is as follows:

I have a .blend file with already existing character geometry. All fine, I rigged it, I animated it - it imports as .fbx to Unity just fine - all the animation clips are present and animating properly (I don’t use .blend file directly due to some issues with newly added bone to already existing and animated armature, which I’m currently going to describe).

My problem starts when I have a model parented to that already animated armature and add just new bone and new geometry that will be attached to it. That new geometry is simply a plane in this case. It shows in Blender just fine, also after reimporting it with .fbx. But, in the Unity, when I render my mesh with use of Skinned Mesh Renderer, all newly added vertices of that new geometry (that plane) are being translated to the position of Root Bone set by that renderer. The already existing geometry that was present in the model before renders fine. When I remove these new vertices from their Vertex Group (which I added manually in Blender to weights group after adding that bone to already existing and animated armature, giving it that bone’s name, it animates fine in Blender) - simply unassigning them - mesh renders fine with that Unity renderer, but of course I have no deformation applied to that part of geometry, which is not what I’m going to achieve.

The reason why I don’t use .blend file directly anymore is because of that new bone’s adding process indeed - I must have broken something with the overall animation structure of that model that is being handled internally by Unity - it results in that when I import it into the engine, the mesh is partially animated (not all the geometry has the deformation applied) and not all of the animation clips are recognized and imported (or there are no clips at all, just the Default Take) - so that’s the matter for another topic which I don’t bother to touch.

I’ll just add that problem concerns only newly added Vertex Group - when I add these vertices to one of already present ones, it renders fine (but of course I can’t apply desired deformations then, that’s why I need new weights group)

Solution - make a backup of a .blend file with old animation clips data, clear animation data of armature, remove all animation clips completely from the scene, recreate them from scratch in Action Editor and copy all the keyframe poses frame-by-frame from backup file to respective newly created animation clips.

You have to do it every time you modify the rig.

Workaround - make this new geometry a separate object and place in Hierarchy as a child of one of bones (works if your animation characteristic is simple enough)

Forgive me but I’m having trouble knowing exactly what your work flow is. It kind of sounds like you are trying to add geometry to the models and reusing your prefabs. Also, .blend files are just the same as .FBX files that you export. Unity simply uses a python script and opens blender then uses the same exporter you use to make an .FBX file. I’ll go over everything I’ve done over the past few months to fix similar problems that I have had.

You need to make sure you rig your model completely before using it in Unity. In fact, general workflow is to let your artist model, rig, and texture your assets before you even start using them. You use simplified prototype/programmer art to fill in for the time being. I had to learn this too as I’m basically artist and programmer, I use a simple shape to stand in for my characters and complete my assets before using them. IF you fully rig your character you should be able to animate later and even during development but you have to be sure to finish the rig before you start animating it or using it in Unity. You’ll run into many problems otherwise. In short Adding new parts to already existing model files in blender causes headaches. Don’t do it.

If you have missing animations, as in the importer doesn’t show them or they aren’t showing up in the mesh asset in the project window, then make sure in blender that all animations have actions tied to them, and make sure each action has a fake user in blender. You may also have to delete the original mesh and save a new version from blender for things to show up right.

If you are noticing that certain bones are not animating and you are using the humanoid type set up, you may have bones that the animator donsen’t recognize as humanoid. You need to get to the configure scene the model in the import inspector to see which bones are not working properly. You can get non humanoid bones to animate by giving the model a mask and including the bones you need to animate.
I hope that helps.