Plugin help: Detecting when a model is added or deleted from the build platform

[bradk3 14]

I would like my plugin to be able to detect when a model is added to or removed to the build platform in Cura. It seems like it should be simple, but I'm clearly not smart enough.

 

The approach I've tried is to connect to the CuraApplication sceneChanged event and watch for changes involving CuraSceneNodes. This works, in that, I can detect when a model is added or removed from the scene, but it also fires when a model is translated or resized, which I do not want.

 

I can't seem to find more information about the scene change, but I may just be clueless. The CuraSceneNode object that is passed to the callback doesn't appear to have any relevant information, nor does the SceneNode object it inherits from.

 

If anyone has any hints, I would appreciate it very much.

[nallath 1,124]

The SceneChanged is a combination of three events:

def _connectSignalsRoot(self) -> None:
    self._root.transformationChanged.connect(self.sceneChanged)
    self._root.childrenChanged.connect(self.sceneChanged)
    self._root.meshDataChanged.connect(self.sceneChanged)

What you're looking for is only the "childrenChanged" of the root:

childrenChanged = Signal()
"""Emitted whenever the list of children of this object or any child object changes.

:param object: The object that triggered the change.
"""

[bradk3 14]

Fantastic! I'm not sure how I missed that in my searching through the source code, but I did.

 

Thank you for the information. That was exactly what I needed.

[nallath 1,124]

So out of curiosity; What plugin are you making?

[Cuq 205]

Very interesting piece of code... @nallath is there any solution to detect if the geometry have changed . I was using in one of my plugin :

 

        self._scene = CuraApplication.getInstance().getController().getScene().getRoot() #type: Scene Root
        self._scene.meshDataChanged.connect(self._onSceneChanged)

 

but it also detect if we change the position of the part position on the buildplate or any modification set on the meshData.

 

 

[Cuq 205]

Not exactly what I'm looking for but jut a little step further.

 

    def _onSceneChanged(self, source: SceneNode) -> None:
        new_scene_objects = set(node for node in BreadthFirstIterator(self._scene) if node.callDecoration("isSliceable"))
        if new_scene_objects != self._scene_objects:
            Logger.log("d", "New_scene_objects")
            self.StandardFixed=0
        
        self._scene_objects = new_scene_objects