NavigationAgent2D

Inherits: Node < Object

2D agent used in navigation for collision avoidance.

Description

2D agent that is used in navigation to reach a location while avoiding static and dynamic obstacles. The dynamic obstacles are avoided using RVO (Reciprocal Velocity Obstacles) collision avoidance. The agent needs navigation data to work correctly. By default this node will register to the default World2D navigation map. If this node is a child of a Navigation2D node it will register to the navigation map of the navigation node or the function set_navigation can be used to set the navigation node directly. NavigationAgent2D is physics safe.

Note: After set_target_location is used it is required to use the get_next_location function once every physics frame to update the internal path logic of the NavigationAgent. The returned vector position from this function should be used as the next movement position for the agent’s parent Node.

Properties

Methods

Signals

• navigation_finished ( )

Notifies when the final location is reached.

• path_changed ( )

Notifies when the navigation path changes. This can be triggered by the navigation system or by the user changing the path.

• target_reached ( )

Notifies when the player-defined target, set with set_target_location, is reached.

• velocity_computed ( Vector2 safe_velocity )

Notifies when the collision avoidance velocity is calculated after a call to set_velocity.

Property Descriptions

• bool avoidance_enabled

If true the agent is registered for an RVO avoidance callback on the Navigation2DServer. When set_velocity is used and the processing is completed a safe_velocity Vector2 is received with a signal connection to velocity_computed. Avoidance processing with many registered agents has a significant performance cost and should only be enabled on agents that currently require it.

• int max_neighbors

The maximum number of neighbors for the agent to consider.

• float max_speed

The maximum speed that an agent can move.

• int navigation_layers

A bitfield determining all navigation map layers the NavigationAgent2D belongs to. On path requests the agent will ignore navmeshes without at least one matching layer.

• float neighbor_dist

The distance to search for other agents.

• float path_desired_distance

The distance threshold before a path point is considered to be reached. This will allow an agent to not have to hit a path point on the path exactly, but in the area. If this value is set to high the NavigationAgent will skip points on the path which can lead to leaving the navigation mesh. If this value is set to low the NavigationAgent will be stuck in a repath loop cause it will constantly overshoot or undershoot the distance to the next point on each physics frame update.

• float path_max_distance

The maximum distance the agent is allowed away from the ideal path to the final location. This can happen due to trying to avoid collisions. When the maximum distance is exceeded, it recalculates the ideal path.

• float radius

The radius of the avoidance agent. This is the “body” of the avoidance agent and not the avoidance maneuver starting radius (which is controlled by neighbor_dist).

Does not affect normal pathfinding.

• float target_desired_distance

The distance threshold before the final target point is considered to be reached. This will allow an agent to not have to hit the point of the final target exactly, but only the area. If this value is set to low the NavigationAgent will be stuck in a repath loop cause it will constantly overshoot or undershoot the distance to the final target point on each physics frame update.

• float time_horizon

The minimal amount of time for which this agent’s velocities, that are computed with the collision avoidance algorithm, are safe with respect to other agents. The larger the number, the sooner the agent will respond to other agents, but the less freedom in choosing its velocities. Must be positive.

Method Descriptions

• float distance_to_target ( ) const

Returns the distance to the target location, using the agent’s global position. The user must set the target location with set_target_location in order for this to be accurate.

• Vector2 get_final_location ( )

Returns the reachable final location in global coordinates. This can change if the navigation path is altered in any way. Because of this, it would be best to check this each frame.

• PoolVector2Array get_nav_path ( ) const

Returns this agent’s current path from start to finish in global coordinates. The path only updates when the target location is changed or the agent requires a repath. The path array is not intended to be used in direct path movement as the agent has its own internal path logic that would get corrupted by changing the path array manually. Use the intended get_next_location once every physics frame to receive the next path point for the agents movement as this function also updates the internal path logic.

• int get_nav_path_index ( ) const

Returns which index the agent is currently on in the navigation path’s PoolVector2Array.

• Node get_navigation ( ) const

Returns the Navigation2D node that the agent is using for its navigation system.

• RID get_navigation_map ( ) const

Returns the RID of the navigation map for this NavigationAgent node. This function returns always the map set on the NavigationAgent node and not the map of the abstract agent on the NavigationServer. If the agent map is changed directly with the NavigationServer API the NavigationAgent node will not be aware of the map change. Use set_navigation_map to change the navigation map for the NavigationAgent and also update the agent on the NavigationServer.

• Vector2 get_next_location ( )

Returns the next location in global coordinates that can be moved to, making sure that there are no static objects in the way. If the agent does not have a navigation path, it will return the position of the agent’s parent. The use of this function once every physics frame is required to update the internal path logic of the NavigationAgent.

• RID get_rid ( ) const

Returns the RID of this agent on the Navigation2DServer.

• Vector2 get_target_location ( ) const

Returns the user-defined target location (set with set_target_location).

• bool is_navigation_finished ( )

Returns true if the navigation path’s final location has been reached.

• bool is_target_reachable ( )

Returns true if the target location is reachable. The target location is set using set_target_location.

• bool is_target_reached ( ) const

Returns true if the target location is reached. The target location is set using set_target_location. It may not always be possible to reach the target location. It should always be possible to reach the final location though. See get_final_location.

• void set_navigation ( Node navigation )

Sets the Navigation2D node used by the agent. Useful when you don’t want to make the agent a child of a Navigation2D node.

• void set_navigation_map ( RID navigation_map )

Sets the RID of the navigation map this NavigationAgent node should use and also updates the agent on the NavigationServer.

• void set_target_location ( Vector2 location )

Sets the user desired final location. This will clear the current navigation path.

• void set_velocity ( Vector2 velocity )

Sends the passed in velocity to the collision avoidance algorithm. It will adjust the velocity to avoid collisions. Once the adjustment to the velocity is complete, it will emit the velocity_computed signal.