add client prediction

scripts/runner.gd

@@ -19,10 +19,16 @@ extends CharacterBody3D
 @export var air_deceleration := 5.0
 @export var rotation_speed := 20.0
 
-@export_group("Client Tweening")
+@export_group("Client Smoothing")
 @export var client_smoothing := false
 @export var client_smoothing_speed := 10.0
 @export var client_smoothing_rotation_speed := 25.0
+@export var client_prediction := false
+@export var client_prediction_tolerance := 0.3
+
+@export_group("Server variables")
+@export var server_position := Vector3.ZERO
+@export var server_rotation := Vector3.ZERO
 
 @onready var _camera_pivot: Node3D = %CameraPivot
 @onready var _camera_platform: Node3D = %CameraPlatform
@@ -32,9 +38,8 @@ extends CharacterBody3D
 var camera_input_direction := Vector2.ZERO
 var last_direction := Vector3.FORWARD
 
-@export_group("Server variables")
-@export var server_position := Vector3.ZERO
-@export var server_rotation := Vector3.ZERO
+var predicted_position := Vector3.ZERO
+var predicted_rotation := Vector3.ZERO
 
 func _ready() -> void:
 	state_machine.set_subject(self)
@@ -80,14 +85,24 @@ func _physics_process(delta: float) -> void:
 		camera_input_direction = Vector2.ZERO
 
 	if not multiplayer.is_server():
-		if client_smoothing:
-			position = lerp(position, server_position, client_smoothing_speed * delta)
-			skin.global_rotation.y = lerp_angle(skin.global_rotation.y, server_rotation.y, client_smoothing_rotation_speed * delta)
-		else:
-			position = server_position
-			skin.global_rotation.y = server_rotation.y
+		if multiplayer.get_unique_id() == player_id and client_prediction:
+			predicted_position = position
+			predicted_rotation = skin.global_rotation
+
+		if multiplayer.get_unique_id() != player_id or not client_prediction:
+			if client_smoothing:
+				position = lerp(position, server_position, client_smoothing_speed * delta)
+				skin.global_rotation.y = lerp_angle(skin.global_rotation.y, server_rotation.y, client_smoothing_rotation_speed * delta)
+			else:
+				position = server_position
+				skin.global_rotation.y = server_rotation.y
 
 	if multiplayer.is_server():
 		server_position = position
 		server_rotation = skin.global_rotation
-		#print("Velocity: %s" % velocity)
+		pass
+
+func _on_sync_delta_synchronized() -> void:
+	if client_prediction and server_position.distance_to(predicted_position) > client_prediction_tolerance:
+		print("%v VS %v" % [server_position, predicted_position])
+		position = server_position

scripts/states/fall.gd

@@ -1,7 +1,7 @@
 extends State
 
 func process_physics(delta: float) -> State:
-	if not multiplayer.is_server():
+	if not multiplayer.is_server() and (multiplayer.get_unique_id() != subject.player_id or not subject.client_prediction):
 		return
 
 	var target_velocity = Vector3(0, subject.velocity.y, 0)

scripts/states/idle.gd

@@ -1,7 +1,7 @@
 extends State
 
 func process_physics(delta: float) -> State:
-	if not multiplayer.is_server():
+	if not multiplayer.is_server() and (multiplayer.get_unique_id() != subject.player_id or not subject.client_prediction):
 		return
 
 	var target_velocity = Vector3(0, subject.velocity.y, 0)

scripts/states/run.gd

@@ -1,7 +1,7 @@
 extends State
 
 func process_physics(delta: float) -> State:
-	if not multiplayer.is_server():
+	if not multiplayer.is_server() and (multiplayer.get_unique_id() != subject.player_id or not subject.client_prediction):
 		return
 
 	var input_direction = %Input.direction

scripts/states/state_machine.gd

@@ -14,7 +14,7 @@ func _change_state(new_state: State) -> void:
 		current_state.exit()
 
 	current_state = new_state
-	print("Entering: %s" % current_state.name)
+	#print("Entering: %s" % current_state.name)
 	current_state.enter()
 
 func process_physics(delta: float) -> void:

scripts/states/walk.gd

@@ -1,7 +1,7 @@
 extends State
 
 func process_physics(delta: float) -> State:
-	if not multiplayer.is_server():
+	if not multiplayer.is_server() and (multiplayer.get_unique_id() != subject.player_id or not subject.client_prediction):
 		return
 
 	var input_direction = %Input.direction