Replace body with WeakRef of body to fix crashes

When a physics body was freed by queue_free or free, it was possible
for the physics update to still happen on the specialized agent. The
Null body then caused a crash.

CHANGELOG.md

@@ -2,6 +2,17 @@
 
 This document lists new features, improvements, changes, and bug fixes in every release of the add-on.
 
+## Godot Steering AI Framework 2.1.1 ##
+
+### Changes ###
+
+- Unused and undocumented variable `_body_type` has been removed from `SpecializedAgent`
+
+### Bug fixes ###
+
+- The specialized agents now use WeakRef internally to prevent crashes when their `body` is freed.
+- `RigidBody2DAgent` now properly connects to physics updates.
+
 ## Godot Steering AI Framework 2.1.0 ##
 
 ### Features ###

project/src/Agents/GSAIKinematicBody2DAgent.gd

@@ -15,17 +15,18 @@ var body: KinematicBody2D setget _set_body
 var movement_type: int
 
 var _last_position: Vector2
+var _body_ref: WeakRef
 
 
 func _init(_body: KinematicBody2D, _movement_type: int = MovementType.SLIDE) -> void:
 	if not _body.is_inside_tree():
 		yield(_body, "ready")
 
-	self.body = _body
+	_body_ref = weakref(_body)
 	self.movement_type = _movement_type
 
 	# warning-ignore:return_value_discarded
-	body.get_tree().connect("physics_frame", self, "_on_SceneTree_physics_frame")
+	_body.get_tree().connect("physics_frame", self, "_on_SceneTree_physics_frame")
 
 
 # Moves the agent's `body` by target `acceleration`.
@@ -44,55 +45,75 @@ func _apply_steering(acceleration: GSAITargetAcceleration, delta: float) -> void
 
 
 func _apply_sliding_steering(accel: Vector3) -> void:
+	var _body: KinematicBody2D = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	var velocity := GSAIUtils.to_vector2(linear_velocity + accel).clamped(linear_speed_max)
 	if apply_linear_drag:
 		velocity = velocity.linear_interpolate(Vector2.ZERO, linear_drag_percentage)
-	velocity = body.move_and_slide(velocity)
+	velocity = _body.move_and_slide(velocity)
 	if calculate_velocities:
 		linear_velocity = GSAIUtils.to_vector3(velocity)
 
 
 func _apply_collide_steering(accel: Vector3, delta: float) -> void:
+	var _body: KinematicBody2D = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	var velocity := GSAIUtils.clampedv3(linear_velocity + accel, linear_speed_max)
 	if apply_linear_drag:
 		velocity = velocity.linear_interpolate(Vector3.ZERO, linear_drag_percentage)
 	# warning-ignore:return_value_discarded
-	body.move_and_collide(GSAIUtils.to_vector2(velocity) * delta)
+	_body.move_and_collide(GSAIUtils.to_vector2(velocity) * delta)
 	if calculate_velocities:
 		linear_velocity = velocity
 
 
 func _apply_position_steering(accel: Vector3, delta: float) -> void:
+	var _body: KinematicBody2D = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	var velocity := GSAIUtils.clampedv3(linear_velocity + accel, linear_speed_max)
 	if apply_linear_drag:
 		velocity = velocity.linear_interpolate(Vector3.ZERO, linear_drag_percentage)
-	body.global_position += GSAIUtils.to_vector2(velocity) * delta
+	_body.global_position += GSAIUtils.to_vector2(velocity) * delta
 	if calculate_velocities:
 		linear_velocity = velocity
 
 
 func _apply_orientation_steering(angular_acceleration: float, delta: float) -> void:
+	var _body: KinematicBody2D = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	var velocity = angular_velocity + angular_acceleration
 	if apply_angular_drag:
 		velocity = lerp(velocity, 0, angular_drag_percentage)
-	body.rotation += velocity * delta
+	_body.rotation += velocity * delta
 	if calculate_velocities:
 		angular_velocity = velocity
 
 
 func _set_body(value: KinematicBody2D) -> void:
-	body = value
+	_body_ref = weakref(body)
 
-	_last_position = body.global_position
-	_last_orientation = body.rotation
+	_last_position = value.global_position
+	_last_orientation = value.rotation
 
 	position = GSAIUtils.to_vector3(_last_position)
 	orientation = _last_orientation
 
 
 func _on_SceneTree_physics_frame() -> void:
-	var current_position := body.global_position
-	var current_orientation := body.rotation
+	var _body: KinematicBody2D = _body_ref.get_ref()
+	if not _body:
+		return
+	
+	var current_position := _body.global_position
+	var current_orientation := _body.rotation
 
 	position = GSAIUtils.to_vector3(current_position)
 	orientation = current_orientation

project/src/Agents/GSAIKinematicBody3DAgent.gd

@@ -15,17 +15,18 @@ var body: KinematicBody setget _set_body
 var movement_type: int
 
 var _last_position: Vector3
+var _body_ref: WeakRef
 
 
 func _init(_body: KinematicBody, _movement_type: int = MovementType.SLIDE) -> void:
 	if not _body.is_inside_tree():
 		yield(_body, "ready")
 
-	self.body = _body
+	self._body_ref = weakref(_body)
 	self.movement_type = _movement_type
 
 	# warning-ignore:return_value_discarded
-	self.body.get_tree().connect("physics_frame", self, "_on_SceneTree_physics_frame")
+	_body.get_tree().connect("physics_frame", self, "_on_SceneTree_physics_frame")
 
 
 # Moves the agent's `body` by target `acceleration`.
@@ -44,55 +45,75 @@ func _apply_steering(acceleration: GSAITargetAcceleration, delta: float) -> void
 
 
 func _apply_sliding_steering(accel: Vector3) -> void:
+	var _body: KinematicBody = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	var velocity := GSAIUtils.clampedv3(linear_velocity + accel, linear_speed_max)
 	if apply_linear_drag:
 		velocity = velocity.linear_interpolate(Vector3.ZERO, linear_drag_percentage)
-	velocity = body.move_and_slide(velocity)
+	velocity = _body.move_and_slide(velocity)
 	if calculate_velocities:
 		linear_velocity = velocity
 
 
 func _apply_collide_steering(accel: Vector3, delta: float) -> void:
+	var _body: KinematicBody = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	var velocity := GSAIUtils.clampedv3(linear_velocity + accel, linear_speed_max)
 	if apply_linear_drag:
 		velocity = velocity.linear_interpolate(Vector3.ZERO, linear_drag_percentage)
 	# warning-ignore:return_value_discarded
-	body.move_and_collide(velocity * delta)
+	_body.move_and_collide(velocity * delta)
 	if calculate_velocities:
 		linear_velocity = velocity
 
 
 func _apply_position_steering(accel: Vector3, delta: float) -> void:
+	var _body: KinematicBody = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	var velocity := GSAIUtils.clampedv3(linear_velocity + accel, linear_speed_max)
 	if apply_linear_drag:
 		velocity = velocity.linear_interpolate(Vector3.ZERO, linear_drag_percentage)
-	body.global_position += velocity * delta
+	_body.global_position += velocity * delta
 	if calculate_velocities:
 		linear_velocity = velocity
 
 
 func _apply_orientation_steering(angular_acceleration: float, delta: float) -> void:
+	var _body: KinematicBody = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	var velocity = angular_velocity + angular_acceleration
 	if apply_angular_drag:
 		velocity = lerp(velocity, 0, angular_drag_percentage)
-	body.rotation.y += velocity * delta
+	_body.rotation.y += velocity * delta
 	if calculate_velocities:
 		angular_velocity = velocity
 
 
 func _set_body(value: KinematicBody) -> void:
-	body = value
+	_body_ref = weakref(value)
 
-	_last_position = body.transform.origin
-	_last_orientation = body.rotation.y
+	_last_position = value.transform.origin
+	_last_orientation = value.rotation.y
 
 	position = _last_position
 	orientation = _last_orientation
 
 
 func _on_SceneTree_physics_frame() -> void:
-	var current_position := body.transform.origin
-	var current_orientation := body.rotation.y
+	var _body: KinematicBody = _body_ref.get_ref()
+	if not _body:
+		return
+		
+	var current_position := _body.transform.origin
+	var current_orientation := _body.rotation.y
 
 	position = current_position
 	orientation = current_orientation

project/src/Agents/GSAIRigidBody2DAgent.gd

@@ -7,43 +7,48 @@ class_name GSAIRigidBody2DAgent
 var body: RigidBody2D setget _set_body
 
 var _last_position: Vector2
+var _body_ref: WeakRef
 
 
 func _init(_body: RigidBody2D) -> void:
 	if not _body.is_inside_tree():
 		yield(_body, "ready")
 
-	self.body = _body
+	_body_ref = weakref(_body)
+	# warning-ignore:return_value_discarded
+	_body.get_tree().connect("physics_frame", self, "_on_SceneTree_frame")
 
 
 # Moves the agent's `body` by target `acceleration`.
 # tags: virtual
 func _apply_steering(acceleration: GSAITargetAcceleration, _delta: float) -> void:
+	var _body: RigidBody2D = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	_applied_steering = true
-	body.apply_central_impulse(GSAIUtils.to_vector2(acceleration.linear))
-	body.apply_torque_impulse(acceleration.angular)
+	_body.apply_central_impulse(GSAIUtils.to_vector2(acceleration.linear))
+	_body.apply_torque_impulse(acceleration.angular)
 	if calculate_velocities:
-		linear_velocity = GSAIUtils.to_vector3(body.linear_velocity)
-		angular_velocity = body.angular_velocity
+		linear_velocity = GSAIUtils.to_vector3(_body.linear_velocity)
+		angular_velocity = _body.angular_velocity
 
 
 func _set_body(value: RigidBody2D) -> void:
-	body = value
+	_body_ref = weakref(value)
 
-	_last_position = body.global_position
-	_last_orientation = body.rotation
+	_last_position = value.global_position
+	_last_orientation = value.rotation
 
 	position = GSAIUtils.to_vector3(_last_position)
 	orientation = _last_orientation
 
 
-func _on_body_ready() -> void:
-	# warning-ignore:return_value_discarded
-	body.get_tree().connect("physics_frame", self, "_on_SceneTree_frame")
-	_set_body(body)
-
-
 func _on_SceneTree_frame() -> void:
+	var _body: RigidBody2D = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	var current_position := body.global_position
 	var current_orientation := body.rotation
 

project/src/Agents/GSAIRigidBody3DAgent.gd

@@ -7,47 +7,49 @@ class_name GSAIRigidBody3DAgent
 var body: RigidBody setget _set_body
 
 var _last_position: Vector3
-
+var _body_ref: WeakRef
 
 func _init(_body: RigidBody) -> void:
 	if not _body.is_inside_tree():
 		yield(_body, "ready")
 
-	self.body = _body
+	_body_ref = weakref(_body)
 	# warning-ignore:return_value_discarded
-	self.body.get_tree().connect("physics_frame", self, "_on_SceneTree_frame")
+	_body.get_tree().connect("physics_frame", self, "_on_SceneTree_frame")
 
 
 # Moves the agent's `body` by target `acceleration`.
 # tags: virtual
 func _apply_steering(acceleration: GSAITargetAcceleration, _delta: float) -> void:
+	var _body: RigidBody = _body_ref.get_ref()
+	if not _body:
+		return
+		
 	_applied_steering = true
-	body.apply_central_impulse(acceleration.linear)
-	body.apply_torque_impulse(Vector3.UP * acceleration.angular)
+	_body.apply_central_impulse(acceleration.linear)
+	_body.apply_torque_impulse(Vector3.UP * acceleration.angular)
 	if calculate_velocities:
-		linear_velocity = body.linear_velocity
-		angular_velocity = body.angular_velocity.y
+		linear_velocity = _body.linear_velocity
+		angular_velocity = _body.angular_velocity.y
 
 
 func _set_body(value: RigidBody) -> void:
-	body = value
+	_body_ref = weakref(value)
 
-	_last_position = body.transform.origin
-	_last_orientation = body.rotation.y
+	_last_position = value.transform.origin
+	_last_orientation = value.rotation.y
 
 	position = _last_position
 	orientation = _last_orientation
 
 
-func _on_body_ready() -> void:
-	# warning-ignore:return_value_discarded
-	body.get_tree().connect("physics_frame", self, "_on_SceneTree_frame")
-	_set_body(body)
-
-
 func _on_SceneTree_frame() -> void:
-	var current_position := body.transform.origin
-	var current_orientation := body.rotation.y
+	var _body: RigidBody = _body_ref.get_ref()
+	if not _body:
+		return
+		
+	var current_position := _body.transform.origin
+	var current_orientation := _body.rotation.y
 
 	position = current_position
 	orientation = current_orientation
@@ -56,5 +58,5 @@ func _on_SceneTree_frame() -> void:
 		if _applied_steering:
 			_applied_steering = false
 		else:
-			linear_velocity = body.linear_velocity
-			angular_velocity = body.angular_velocity.y
+			linear_velocity = _body.linear_velocity
+			angular_velocity = _body.angular_velocity.y

project/src/Agents/GSAISpecializedAgent.gd

@@ -29,7 +29,6 @@ var linear_drag_percentage := 0.0
 var angular_drag_percentage := 0.0
 
 var _last_orientation: float
-var _body_type: int
 var _applied_steering := false