Blender passive rigid bodies generate no Bullet physics nodes.

[Clockwork-Muse]

When gltf files are imported or converted into .bam files, or files are auto-converted by the blend loader, and use Bullet physics, there are no Bullet physics nodes generated for Blender passive rigid bodies. Instead an empty node of some sort is generated:

class MyApp(ShowBase):
    def __init__(self):
        super().__init__(self)
        self.world = BulletWorld()

        self.model = self.loader.loadModel("repro.blend.bam")
        self.model.reparentTo(self.render)
        physics_node = self.model.find("**/+BulletBodyNode")
        if physics_node:
            print(physics_node.node())
        else:
            print(None)

        self.render.ls()

        query_node = self.model.children[0].children[1]
        print(query_node.node())

Outputs:

None
PandaNode render S:(CullFaceAttrib RescaleNormalAttrib)
  ModelRoot Scene
    PandaNode Cube
      GeomNode Cube (1 geoms: S:(CullFaceAttrib MaterialAttrib TextureAttrib))
      PandaNode Cube
PandaNode Cube

exporting the file with builtin physics does generate the anticipated (currently intangible) CollisionBodyNode, so presumably the gltf file itself is fine:

None
PandaNode render S:(CullFaceAttrib RescaleNormalAttrib)
  ModelRoot Scene
    PandaNode Cube
      GeomNode Cube (1 geoms: S:(CullFaceAttrib MaterialAttrib TextureAttrib))
      CollisionNode Cube (1 solids) (hidden)
CollisionNode Cube (1 solids) (hidden)

(I wish there was an easy way to observe the intermediate file)

[Moguri]

A BulletGhostNode is getting created as expected, but it looks like BulletGhostNode does not implement BAM serialization. In other words, this is an issue in Panda, and I am not sure if there is an appropriate work around we can implement in this library.

[Clockwork-Muse]

.... good to know...

[rdb]

Actually, passive rigid bodies should not be exported as BulletGhostNode, but rather as a BulletRigidBodyNode with zero mass. In Blender, "passive" means that the body is not affected by forces, but it does participate in collision detection.

[Clockwork-Muse]

@rdb - I would prefer that too (and should be static on top of that), but there's other issues to track that particular question. The exporter just currently exports all passive bodies as "intangible".

[Clockwork-Muse]

Fixed in panda3d/panda3d#1104