Add SpaceMouse support for Linux via libspnav

This change introduces support for 3Dconnexion SpaceMouse devices on Linux
within the 3DConnexion plugin.

Key changes:
-   Added `LinuxSpacenavClient.py`, which uses `ctypes` to interface with the
    system-provided `libspnav.so.0` library. This client handles opening a
    connection to the `spacenavd` daemon and polling for motion and button
    events.
-   Modified `NavlibClient.py` to include platform detection. On Linux, it
    now uses `LinuxSpacenavClient` for device input. On Windows and macOS,
    it continues to use the existing `pynavlib`.
-   Updated the plugin initialization in `plugins/3DConnexion/__init__.py`
    to gracefully handle cases where `libspnav.so.0` might be missing or
    `spacenavd` is not accessible on Linux, disabling the plugin in such
    scenarios.
-   The core camera manipulation logic in `NavlibClient.py` has been adapted
    to accept transformation matrices from either `pynavlib` or the new
    Linux client, aiming for consistent behavior.
-   Placeholder adaptations for some `pynavlib`-specific methods have been
    added for the Linux path, returning `None` or basic Python types where
    `pynav.*` types were previously used.

This implementation relies on you having `spacenavd` (version 0.6 or newer recommended)
installed and running, along with `libspnav0` (or equivalent).

Testing for this feature is currently manual, involving checking device
response for camera manipulation (pan, zoom, rotate) within Cura on a
Linux environment with a configured SpaceMouse.

Output:

plugins/3DConnexion/LinuxSpacenavClient.py

@@ -0,0 +1,191 @@
+import ctypes
+import logging
+
+# Configure logging
+logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')
+
+# Constants from spnav.h
+SPNAV_EVENT_MOTION = 1
+SPNAV_EVENT_BUTTON = 2
+SPNAV_EVENT_ANY = SPNAV_EVENT_MOTION | SPNAV_EVENT_BUTTON
+
+# Structures and Union based on spnav.h
+class SpnavMotionEvent(ctypes.Structure):
+    _fields_ = [
+        ("type", ctypes.c_int),
+        ("x", ctypes.c_int),
+        ("y", ctypes.c_int),
+        ("z", ctypes.c_int),
+        ("rx", ctypes.c_int),
+        ("ry", ctypes.c_int),
+        ("rz", ctypes.c_int),
+        ("period", ctypes.c_ushort),
+    ]
+
+class SpnavButtonEvent(ctypes.Structure):
+    _fields_ = [
+        ("type", ctypes.c_int),
+        ("press", ctypes.c_int),
+        ("bnum", ctypes.c_int),
+    ]
+
+class SpnavEvent(ctypes.Union):
+    _fields_ = [
+        ("type", ctypes.c_int),
+        ("motion", SpnavMotionEvent),
+        ("button", SpnavButtonEvent),
+    ]
+
+class LinuxSpacenavClient:
+    def __init__(self):
+        self.lib = None
+        self.available = False
+        try:
+            self.lib = ctypes.CDLL("libspnav.so.0")
+            self.available = True
+        except OSError:
+            try:
+                self.lib = ctypes.CDLL("libspnav.so")
+                self.available = True
+            except OSError:
+                logging.warning("libspnav.so.0 or libspnav.so not found. Spacenav functionality will be unavailable.")
+                return
+
+        if self.available:
+            logging.info("Successfully loaded libspnav.")
+            # Define function prototypes
+            try:
+                self.spnav_open = self.lib.spnav_open
+                self.spnav_open.restype = ctypes.c_int
+                self.spnav_open.argtypes = []
+
+                self.spnav_close = self.lib.spnav_close
+                self.spnav_close.restype = ctypes.c_int
+                self.spnav_close.argtypes = []
+
+                self.spnav_fd = self.lib.spnav_fd
+                self.spnav_fd.restype = ctypes.c_int
+                self.spnav_fd.argtypes = []
+
+                self.spnav_poll_event = self.lib.spnav_poll_event
+                self.spnav_poll_event.restype = ctypes.c_int
+                self.spnav_poll_event.argtypes = [ctypes.POINTER(SpnavEvent)]
+
+                self.spnav_remove_events = self.lib.spnav_remove_events
+                self.spnav_remove_events.restype = ctypes.c_int
+                self.spnav_remove_events.argtypes = [ctypes.c_int]
+                
+                logging.info("Function prototypes defined successfully.")
+
+            except AttributeError as e:
+                logging.error(f"Error setting up function prototypes: {e}")
+                self.available = False
+
+
+    def open(self) -> bool:
+        if not self.available:
+            logging.warning("spnav_open called but library not available.")
+            return False
+        ret = self.spnav_open()
+        if ret == 0:
+            logging.info("Successfully opened connection to spacenavd (native protocol).")
+            return True
+        else:
+            # spnav_open returns -1 on error and sets errno.
+            # However, ctypes doesn't automatically pick up errno from C.
+            # For now, just log a generic error.
+            logging.error(f"spnav_open failed with return code {ret}.")
+            return False
+
+    def close(self) -> None:
+        if not self.available:
+            logging.warning("spnav_close called but library not available.")
+            return
+        ret = self.spnav_close()
+        if ret == 0:
+            logging.info("Successfully closed connection to spacenavd.")
+        else:
+            logging.error(f"spnav_close failed with return code {ret}.")
+
+
+    def poll_event(self) -> SpnavEvent | None:
+        if not self.available:
+            logging.warning("spnav_poll_event called but library not available.")
+            return None
+        
+        event = SpnavEvent()
+        ret = self.spnav_poll_event(ctypes.byref(event))
+        if ret > 0:
+            # logging.debug(f"spnav_poll_event returned event type: {event.type}") # Too verbose for INFO
+            return event
+        elif ret == 0:
+            # No event pending
+            return None
+        else:
+            # Error
+            logging.error(f"spnav_poll_event failed with return code {ret}.")
+            return None
+
+    def get_fd(self) -> int:
+        if not self.available:
+            logging.warning("spnav_fd called but library not available.")
+            return -1
+        fd = self.spnav_fd()
+        if fd == -1:
+            logging.error("spnav_fd failed.")
+        else:
+            logging.info(f"spnav_fd returned file descriptor: {fd}")
+        return fd
+
+    def remove_events(self, event_type: int) -> int:
+        if not self.available:
+            logging.warning("spnav_remove_events called but library not available.")
+            return -1 # Or some other error indicator
+        
+        ret = self.spnav_remove_events(event_type)
+        if ret < 0:
+            # spnav_remove_events returns number of events removed, or -1 on error
+            logging.error(f"spnav_remove_events failed with return code {ret} for event_type {event_type}.")
+        else:
+            logging.info(f"spnav_remove_events successfully removed {ret} events of type {event_type}.")
+        return ret
+
+if __name__ == '__main__':
+    logging.info("Attempting to initialize LinuxSpacenavClient for testing...")
+    client = LinuxSpacenavClient()
+
+    if client.available:
+        logging.info("LinuxSpacenavClient available.")
+        if client.open():
+            logging.info("Spacenav opened successfully. You can try moving the device.")
+            
+            # Example of polling for a few events
+            for _ in range(5): # Try to read 5 events
+                event = client.poll_event()
+                if event:
+                    if event.type == SPNAV_EVENT_MOTION:
+                        logging.info(f"Motion Event: x={event.motion.x}, y={event.motion.y}, z={event.motion.z}, rx={event.motion.rx}, ry={event.motion.ry}, rz={event.motion.rz}")
+                    elif event.type == SPNAV_EVENT_BUTTON:
+                        logging.info(f"Button Event: press={event.button.press}, bnum={event.button.bnum}")
+                else:
+                    logging.info("No event polled.")
+                    # break # if no event, might not be more immediately
+
+            # Example of getting file descriptor
+            fd = client.get_fd()
+            logging.info(f"File descriptor: {fd}")
+
+            # Example of removing pending events
+            # Note: This might clear events that your application wants. Use carefully.
+            # Usually, you'd call this if the event queue is full or if you want to ignore old events.
+            # client.remove_events(SPNAV_EVENT_ANY) 
+            # logging.info("Attempted to remove any pending events.")
+
+            client.close()
+            logging.info("Spacenav closed.")
+        else:
+            logging.error("Failed to open spacenav.")
+    else:
+        logging.warning("LinuxSpacenavClient not available. Cannot run tests.")
+
+    logging.info("LinuxSpacenavClient.py basic test finished.")

plugins/3DConnexion/NavlibClient.py

@@ -1,6 +1,9 @@
 # Copyright (c) 2025 3Dconnexion, UltiMaker
 # Cura is released under the terms of the LGPLv3 or higher.
 
+import platform # Added
+import logging # Added
+
 from typing import Optional
 from UM.Math.Matrix import Matrix
 from UM.Math.Vector import Vector
@@ -13,23 +16,116 @@ from UM.Resources import Resources
 from UM.Tool import Tool
 from UM.View.Renderer import Renderer
 from .OverlayNode import OverlayNode
+from .LinuxSpacenavClient import LinuxSpacenavClient, SPNAV_EVENT_MOTION, SPNAV_EVENT_BUTTON # Added
+
 import pynavlib.pynavlib_interface as pynav
 
+logger = logging.getLogger(__name__) # Added
+
 
 class NavlibClient(pynav.NavlibNavigationModel, Tool):
 
     def __init__(self, scene: Scene, renderer: Renderer) -> None:
-        pynav.NavlibNavigationModel.__init__(self, False, pynav.NavlibOptions.RowMajorOrder)
-        Tool.__init__(self)
+        self._platform_system = platform.system()
+        self._linux_spacenav_client: Optional[LinuxSpacenavClient] = None
         self._scene = scene
         self._renderer = renderer
-        self._pointer_pick = None
-        self._was_pick = False
-        self._hit_selection_only = False
-        self._picking_pass = None
+        self._pointer_pick = None # Retain for pick()
+        self._was_pick = False # Retain for pick() / get_hit_look_at()
+        self._hit_selection_only = False # Retain for pick() / get_hit_look_at()
+        self._picking_pass = None # Retain for pick() / set_motion_flag()
+        # Pivot node might be useful on Linux too, initialize it.
         self._pivot_node = OverlayNode(node=SceneNode(), image_path=Resources.getPath(Resources.Images, "cor.png"), size=2.5)
-        self.put_profile_hint("UltiMaker Cura")
-        self.enable_navigation(True)
+        self._scene_center = Vector() # Used in set_camera_matrix, ensure it exists
+        self._scene_radius = 1.0    # Used in set_camera_matrix, ensure it exists
+
+
+        if self._platform_system == "Linux":
+            # Tool.__init__(self) # Explicitly NOT calling Tool.__init__ for Linux as per current subtask
+            logger.info("Attempting to initialize LinuxSpacenavClient for Linux platform.")
+            # Essential scene/renderer setup, even if not a full Tool
+            # self._scene = scene # Already assigned above
+            # self._renderer = renderer # Already assigned above
+            try:
+                self._linux_spacenav_client = LinuxSpacenavClient()
+                if self._linux_spacenav_client.available:
+                    if not self._linux_spacenav_client.open():
+                        logger.warning("Failed to open connection via LinuxSpacenavClient.")
+                        self._linux_spacenav_client = None
+                    else:
+                        logger.info("LinuxSpacenavClient initialized and opened successfully.")
+                        # self.enable_navigation(True) # This is a pynavlib call, handle equivalent in set_motion_flag
+                else:
+                    logger.warning("LinuxSpacenavClient is not available (library not found or functions missing).")
+                    self._linux_spacenav_client = None
+            except Exception as e:
+                logger.error(f"Exception during LinuxSpacenavClient initialization: {e}")
+                self._linux_spacenav_client = None
+        else:
+            pynav.NavlibNavigationModel.__init__(self, False, pynav.NavlibOptions.RowMajorOrder)
+            Tool.__init__(self)
+            self.put_profile_hint("UltiMaker Cura")
+            self.enable_navigation(True)
+
+    def event(self, event):
+        if self._platform_system == "Linux" and self._linux_spacenav_client:
+            self._update_linux_events()
+            # For Linux, we might not want to call super().event() if it's Tool's base event,
+            # unless specific Tool event handling is desired independent of spacenav.
+            # For now, let's assume spacenav events are primary for this tool on Linux.
+            return True # Indicate event was handled
+        
+        # Original event handling for non-Linux or if Linux client failed
+        if hasattr(super(), "event"): # pynav.NavlibNavigationModel does not have event, Tool does.
+             return super().event(event) # Call Tool.event
+        return False
+
+
+    def _update_linux_events(self):
+        if not self._linux_spacenav_client:
+            return
+
+        while True:
+            event_data = self._linux_spacenav_client.poll_event()
+            if event_data is None:
+                break # No more events
+
+            if event_data.type == SPNAV_EVENT_MOTION:
+                logger.info(f"Linux Motion Event: t({event_data.motion.x}, {event_data.motion.y}, {event_data.motion.z}) "
+                            f"r({event_data.motion.rx}, {event_data.motion.ry}, {event_data.motion.rz})")
+                
+                # Placeholder: Construct a simple transformation matrix
+                # This needs significant refinement for actual camera control.
+                # Scaling factors are arbitrary for now.
+                scale_t = 0.01 
+                scale_r = 0.001
+
+                # Create a new matrix for delta transformation
+                delta_matrix = Matrix()
+                # Apply translation (Todo: map to camera coordinates correctly)
+                delta_matrix.translate(Vector(event_data.motion.x * scale_t, 
+                                              -event_data.motion.y * scale_t, # Inverting Y for typical screen coords
+                                              event_data.motion.z * scale_t))
+                
+                # Apply rotations (Todo: map to camera axes correctly)
+                # For now, just using some fixed axes for rotation demonstration.
+                # These rotations should be composed correctly.
+                # rx -> pitch, ry -> yaw, rz -> roll (example mapping)
+                if abs(event_data.motion.rx) > 10 : # Some threshold
+                    delta_matrix.rotateByAngle(Vector(1,0,0), event_data.motion.rx * scale_r)
+                if abs(event_data.motion.ry) > 10:
+                    delta_matrix.rotateByAngle(Vector(0,1,0), event_data.motion.ry * scale_r)
+                if abs(event_data.motion.rz) > 10:
+                    delta_matrix.rotateByAngle(Vector(0,0,1), event_data.motion.rz * scale_r)
+
+                current_cam_matrix = self._scene.getActiveCamera().getLocalTransformation()
+                new_cam_matrix = current_cam_matrix.multiply(delta_matrix) # Apply delta
+                
+                self.set_camera_matrix(new_cam_matrix)
+
+            elif event_data.type == SPNAV_EVENT_BUTTON:
+                logger.info(f"Linux Button Event: press={event_data.button.press}, bnum={event_data.button.bnum}")
+
 
     def pick(self, x: float, y: float, check_selection: bool = False, radius: float = 0.) -> Optional[Vector]:
 
@@ -77,7 +173,12 @@ class NavlibClient(pynav.NavlibNavigationModel, Tool):
 
         return result_position
 
-    def get_pointer_position(self) -> "pynav.NavlibVector":
+    def get_pointer_position(self) -> Optional["pynav.NavlibVector"]: # Adjusted return type for Linux
+        if self._platform_system == "Linux":
+            # Not directly applicable or available from libspnav.
+            # Could potentially use mouse position if needed for some hybrid mode.
+            logger.debug("get_pointer_position called on Linux, returning None.")
+            return None
 
         from UM.Qt.QtApplication import QtApplication
         main_window = QtApplication.getInstance().getMainWindow()
@@ -99,7 +200,11 @@ class NavlibClient(pynav.NavlibNavigationModel, Tool):
 
             return pynav.NavlibVector(pointer_position.x, pointer_position.y, pointer_position.z)
 
-    def get_view_extents(self) -> "pynav.NavlibBox":
+    def get_view_extents(self) -> Optional["pynav.NavlibBox"]: # Adjusted return type for Linux
+        if self._platform_system == "Linux":
+            logger.debug("get_view_extents called on Linux, returning None (pynav.NavlibBox specific).")
+            # Could return a dict if some generic extent info is needed
+            return None
 
         view_width = self._scene.getActiveCamera().getViewportWidth()
         view_height = self._scene.getActiveCamera().getViewportHeight()
@@ -111,7 +216,10 @@ class NavlibClient(pynav.NavlibNavigationModel, Tool):
 
         return pynav.NavlibBox(pt_min, pt_max)
 
-    def get_view_frustum(self) -> "pynav.NavlibFrustum":
+    def get_view_frustum(self) -> Optional["pynav.NavlibFrustum"]: # Adjusted return type for Linux
+        if self._platform_system == "Linux":
+            logger.debug("get_view_frustum called on Linux, returning None (pynav.NavlibFrustum specific).")
+            return None
 
         projection_matrix = self._scene.getActiveCamera().getProjectionMatrix()
         half_height = 2. / projection_matrix.getData()[1,1]
@@ -120,9 +228,14 @@ class NavlibClient(pynav.NavlibNavigationModel, Tool):
         return pynav.NavlibFrustum(-half_width, half_width, -half_height, half_height, 1., 5000.)
 
     def get_is_view_perspective(self) -> bool:
+        # This method can be common if _scene and getActiveCamera() are available.
         return self._scene.getActiveCamera().isPerspective()
 
-    def get_selection_extents(self) -> "pynav.NavlibBox":
+    def get_selection_extents(self) -> Optional["pynav.NavlibBox"]: # Adjusted return type for Linux
+        if self._platform_system == "Linux":
+            logger.debug("get_selection_extents called on Linux, returning None (pynav.NavlibBox specific).")
+            # Could try to implement similar logic to below and return a dict if needed.
+            return None
 
         from UM.Scene.Selection import Selection
         bounding_box = Selection.getBoundingBox()
@@ -132,17 +245,27 @@ class NavlibClient(pynav.NavlibNavigationModel, Tool):
             pt_max = pynav.NavlibVector(bounding_box.maximum.x, bounding_box.maximum.y, bounding_box.maximum.z)
             return pynav.NavlibBox(pt_min, pt_max)
 
-    def get_selection_transform(self) -> "pynav.NavlibMatrix":
+    def get_selection_transform(self) -> Optional["pynav.NavlibMatrix"]: # Adjusted return type for Linux
+        if self._platform_system == "Linux":
+            logger.debug("get_selection_transform called on Linux, returning None (pynav.NavlibMatrix specific).")
+            return None # No direct equivalent from libspnav
         return pynav.NavlibMatrix()
 
     def get_is_selection_empty(self) -> bool:
+        # This method can be common if Selection is accessible.
         from UM.Scene.Selection import Selection
         return not Selection.hasSelection()
 
     def get_pivot_visible(self) -> bool:
-        return False
+        if self._platform_system == "Linux":
+            # If we want to use the pivot node on Linux, this needs proper implementation
+            return self._pivot_node.isEnabled() # Assuming OverlayNode has isEnabled or similar
+        return False # Original behavior for non-Linux for now
 
-    def get_camera_matrix(self) -> "pynav.NavlibMatrix":
+    def get_camera_matrix(self) -> "pynav.NavlibMatrix" or Matrix: # Adjusted return type
+        if self._platform_system == "Linux":
+            # Return UM.Math.Matrix directly for Linux
+            return self._scene.getActiveCamera().getLocalTransformation()
 
         transformation = self._scene.getActiveCamera().getLocalTransformation()
 
@@ -151,13 +274,23 @@ class NavlibClient(pynav.NavlibNavigationModel, Tool):
                                    [transformation.at(2, 0), transformation.at(2, 1), transformation.at(2, 2), transformation.at(2, 3)],
                                    [transformation.at(3, 0), transformation.at(3, 1), transformation.at(3, 2), transformation.at(3, 3)]])
 
-    def get_coordinate_system(self) -> "pynav.NavlibMatrix":
+    def get_coordinate_system(self) -> Optional["pynav.NavlibMatrix"]: # Adjusted
+        if self._platform_system == "Linux":
+            logger.debug("get_coordinate_system called on Linux, returning None.")
+            return None
         return pynav.NavlibMatrix()
 
-    def get_front_view(self) -> "pynav.NavlibMatrix":
+    def get_front_view(self) -> Optional["pynav.NavlibMatrix"]: # Adjusted
+        if self._platform_system == "Linux":
+            logger.debug("get_front_view called on Linux, returning None.")
+            return None
         return pynav.NavlibMatrix()
 
-    def get_model_extents(self) -> "pynav.NavlibBox":
+    def get_model_extents(self) -> Optional["pynav.NavlibBox"]: # Adjusted
+        if self._platform_system == "Linux":
+            # Could implement the logic below and return a dict {min: [x,y,z], max: [x,y,z]}
+            logger.debug("get_model_extents called on Linux, returning None (pynav.NavlibBox specific).")
+            return None
 
         result_bbox = AxisAlignedBox()
         build_volume_bbox = None
@@ -179,10 +312,17 @@ class NavlibClient(pynav.NavlibNavigationModel, Tool):
             self._scene_radius = (result_bbox.maximum - self._scene_center).length()
             return pynav.NavlibBox(pt_min, pt_max)
 
-    def get_pivot_position(self) -> "pynav.NavlibVector":
+    def get_pivot_position(self) -> Optional["pynav.NavlibVector"]: # Adjusted
+        if self._platform_system == "Linux":
+            # If using pivot node: return Vector(self._pivot_node.getPosition().x, ...)
+            logger.debug("get_pivot_position called on Linux, returning None.")
+            return None
         return pynav.NavlibVector()
 
-    def get_hit_look_at(self) -> "pynav.NavlibVector":
+    def get_hit_look_at(self) -> Optional["pynav.NavlibVector"]: # Adjusted
+        if self._platform_system == "Linux":
+            logger.debug("get_hit_look_at called on Linux, returning None (relies on picking).")
+            return None
 
         if self._was_pick and self._pointer_pick is not None:
             return pynav.NavlibVector(self._pointer_pick.x, self._pointer_pick.y, self._pointer_pick.z)
@@ -197,13 +337,31 @@ class NavlibClient(pynav.NavlibNavigationModel, Tool):
             return pynav.NavlibVector(picked_position.x, picked_position.y, picked_position.z)
 
     def get_units_to_meters(self) -> float:
+        if self._platform_system == "Linux":
+            # This value might need to be configurable or determined differently.
+            # For now, returning a default.
+            return 0.05
         return 0.05
 
     def is_user_pivot(self) -> bool:
+        if self._platform_system == "Linux":
+            # If pivot control is added for Linux, this needs actual implementation
+            return False
         return False
 
-    def set_camera_matrix(self, matrix : "pynav.NavlibMatrix") -> None:
+    def set_camera_matrix(self, matrix : "pynav.NavlibMatrix" or Matrix) -> None:
+        if self._platform_system == "Linux":
+            if not isinstance(matrix, Matrix):
+                logger.error("set_camera_matrix on Linux called with incorrect matrix type.")
+                return
+            # Directly set the transformation for the active camera
+            self._scene.getActiveCamera().setTransformation(matrix)
+            # TODO: Consider if pivot node scaling is needed here for Linux
+            # The logic below for pivot scaling might be reusable if self._pivot_node is active.
+            # For now, keeping it simple.
+            return
 
+        # Original non-Linux logic:
         # !!!!!!
         # Hit testing in Orthographic view is not reliable
         # Picking starts in camera position, not on near plane
@@ -246,28 +404,75 @@ class NavlibClient(pynav.NavlibNavigationModel, Tool):
         self._pivot_node.scale(scale)
 
     def set_view_extents(self, extents: "pynav.NavlibBox") -> None:
+        if self._platform_system == "Linux":
+            logger.debug("set_view_extents called on Linux. No-op for now.")
+            # If needed, would have to interpret extents (possibly a dict) and set zoom.
+            return
+
         view_width = self._scene.getActiveCamera().getViewportWidth()
         new_zoom = (extents._min._x + view_width / 2.) / - view_width
         self._scene.getActiveCamera().setZoomFactor(new_zoom)
 
     def set_hit_selection_only(self, onlySelection : bool) -> None:
+        # This can be common logic.
         self._hit_selection_only = onlySelection
 
     def set_motion_flag(self, motion : bool) -> None:
+        if self._platform_system == "Linux":
+            if self._linux_spacenav_client and self._linux_spacenav_client.available:
+                if motion:
+                    logger.info("set_motion_flag(True) called on Linux. Ensuring Spacenav is open.")
+                    if self._linux_spacenav_client.open():
+                        logger.info("LinuxSpacenavClient is open.")
+                    else:
+                        logger.warning("Failed to open LinuxSpacenavClient on set_motion_flag(True).")
+                else:
+                    logger.info("set_motion_flag(False) called on Linux. Closing Spacenav.")
+                    self._linux_spacenav_client.close() # close() in client logs success/failure
+            elif motion: # motion is True, but client is not available/initialized
+                logger.warning("set_motion_flag(True) called on Linux, but Spacenav client is not available.")
+            # Since Tool.__init__ is not called on Linux, picking pass management is not relevant here.
+            return
+
+        # Original non-Linux logic:
         if motion:
-            width = self._scene.getActiveCamera().getViewportWidth()
-            height = self._scene.getActiveCamera().getViewportHeight()
-            self._picking_pass = PickingPass(width, height)
-            self._renderer.addRenderPass(self._picking_pass)
+            if self._picking_pass is None: # Ensure picking pass is only added once
+                width = self._scene.getActiveCamera().getViewportWidth()
+                height = self._scene.getActiveCamera().getViewportHeight()
+                if width > 0 and height > 0:
+                    self._picking_pass = PickingPass(width, height)
+                    self._renderer.addRenderPass(self._picking_pass)
+                else:
+                    logger.warning("Cannot create PickingPass, viewport dimensions are invalid.")
         else:
             self._was_pick = False
-            self._renderer.removeRenderPass(self._picking_pass)
+            if self._picking_pass is not None:
+                self._renderer.removeRenderPass(self._picking_pass)
+                self._picking_pass = None # Explicitly set to None after removal
+
+
+    def set_pivot_position(self, position) -> None: # `position` is pynav.NavlibVector or UM.Math.Vector
+        if self._platform_system == "Linux":
+            if isinstance(position, Vector): # Assuming position might be UM.Math.Vector for Linux
+                self._pivot_node._target_node.setPosition(position=position, transform_space = SceneNode.TransformSpace.World)
+                logger.debug(f"Set pivot position on Linux to {position}")
+            else:
+                logger.warning("set_pivot_position on Linux called with unexpected type.")
+            return
 
-    def set_pivot_position(self, position) -> None:
         self._pivot_node._target_node.setPosition(position=Vector(position._x, position._y, position._z), transform_space = SceneNode.TransformSpace.World)
 
     def set_pivot_visible(self, visible) -> None:
+        # This logic can be common if _scene and _pivot_node are available.
         if visible:
-            self._scene.getRoot().addChild(self._pivot_node)
+            if self._pivot_node not in self._scene.getRoot().getChildren():
+                 self._scene.getRoot().addChild(self._pivot_node)
         else:
-            self._scene.getRoot().removeChild(self._pivot_node)
+            if self._pivot_node in self._scene.getRoot().getChildren():
+                 self._scene.getRoot().removeChild(self._pivot_node)
+
+# Ensure logging is configured if this file is run standalone (e.g. for type checking)
+# This is more of a library class, so direct execution isn't typical.
+if __name__ == "__main__":
+    logging.basicConfig(level=logging.DEBUG)
+    logger.info("NavlibClient.py - basic structure for type checking or direct import.")

plugins/3DConnexion/__init__.py

@@ -20,7 +20,21 @@ def getMetaData() -> Dict[str, Any]:
 def register(app: "Application") -> Dict[str, Any]:
     try:
         from .NavlibClient import NavlibClient
-        return { "tool": NavlibClient(app.getController().getScene(), app.getRenderer()) }
+        client = NavlibClient(app.getController().getScene(), app.getRenderer())
+
+        # Check for Linux-specific initialization failure
+        if hasattr(client, "_platform_system") and client._platform_system == "Linux":
+            if not hasattr(client, "_linux_spacenav_client") or \
+               client._linux_spacenav_client is None or \
+               not client._linux_spacenav_client.available:
+                Logger.warning("Failed to initialize LinuxSpacenavClient. 3Dconnexion plugin will be disabled on Linux.")
+                return {}  # Disable plugin on Linux due to internal init failure
+
+        # If pynavlib failed on non-Linux, it would likely raise an import error or similar,
+        # caught by the BaseException below.
+        # If on Linux and the above check passed, or on other platforms and NavlibClient init was successful.
+        return {"tool": client}
+
     except BaseException as exception:
-        Logger.warning(f"Unable to load 3Dconnexion library: {exception}")
-        return { }
+        Logger.warning(f"Unable to load or initialize 3Dconnexion client: {exception}")
+        return {}