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Using NavigationServer

2D and 3D version of the NavigationServer are available as NavigationServer2D and NavigationServer3D respectively.

Both 2D and 3D use the same NavigationServer with NavigationServer3D being the primary server. The NavigationServer2D is a frontend that converts 2D positions into 3D positions and back. Hence it is entirely possible (if not a little cumbersome) to exclusively use the NavigationServer3D API for 2D navigation.

Communicating with the NavigationServer

To work with the NavigationServer means to prepare parameters for a query that can be send to the NavigationServer for updates or requesting data.

To reference the internal NavigationServer objects like maps, regions and agents RIDs are used as identification numbers. Every navigation related node in the SceneTree has a function that returns the RID for this node.

Threading and Synchronization

The NavigationServer does not update every change immediately but waits until the end of the physics_frame to synchronize all the changes together.

Waiting for synchronization is required to apply changes to all maps, regions and agents. Synchronization is done because some updates like a recalculation of the entire navigation map are very expensive and require updated data from all other objects. Also the NavigationServer uses a threadpool by default for some functionality like avoidance calculation between agents.

Waiting is not required for most get() functions that only request data from the NavigationServer without making changes. Note that not all data will account for changes made in the same frame. E.g. if an avoidance agent changed the navigation map this frame the agent_get_map() function will still return the old map before the synchronization. The exception to this are nodes that store their values internally before sending the update to the NavigationServer. When a getter on a node is used for a value that was updated in the same frame it will return the already updated value stored on the node.

The NavigationServer is thread-safe as it places all API calls that want to make changes in a queue to be executed in the synchronization phase. Synchronization for the NavigationServer happens in the middle of the physics frame after scene input from scripts and nodes are all done.

Note

The important takeaway is that most NavigationServer changes take effect after the next physics frame and not immediately. This includes all changes made by navigation related nodes in the SceneTree or through scripts.

The following functions will be executed in the synchronization phase only:

  • map_set_active()

  • map_set_up()

  • map_set_cell_size()

  • map_set_edge_connection_margin()

  • region_set_map()

  • region_set_transform()

  • region_set_enter_cost()

  • region_set_travel_cost()

  • region_set_navigation_layers()

  • region_set_navigation_mesh()

  • agent_set_map()

  • agent_set_neighbor_dist()

  • agent_set_max_neighbors()

  • agent_set_time_horizon()

  • agent_set_radius()

  • agent_set_max_speed()

  • agent_set_velocity()

  • agent_set_target_velocity()

  • agent_set_position()

  • agent_set_ignore_y()

  • agent_set_callback()

  • free()

2D and 3D NavigationServer differences

NavigationServer2D and NavigationServer3D are equivalent in functionality for their dimension and both use the same NavigationServer behind the scene.

Strictly technical a NavigationServer2D is a myth. The NavigationServer2D is a frontend to facilitate conversions of Vector2(x, y) to Vector3(x, 0.0, z) and back for the NavigationServer3D API. 2D uses a flat 3D mesh pathfinding and the NavigationServer2D facilitates the conversions. When a guide uses just