I tried to set/enable/disable the layers from a THREE.Group and respectively to the camera in action, but without any luck, showing/hiding different parts of the scene. Setting the layers of a mesh-object works just fine, and behaves like expected.
It would be nice to use layers beside groups, so the children-layers can behave as a kind of a subsystem for the group.
Right know, you have to traverse through the group and set the layer property for all children to the intended value. Have a look at the following thread for more information.
The layer test is performed per object and has no effect on child objects. If you think this behavior should be different, it’s best to create a feature request at github.