Ball gets culled if velocity is low after rolling for a while

src/equipment/balls/physics_ball/game_ball.gd

@@ -14,7 +14,6 @@ enum Type {
 	POWER,
 }
 
-const VELOCITY_SQ_EPSILON := 1e-4
 const MAGNUS_SQ_EPSILON := 1e-3
 
 ## If enabled, ball ability cooldown is only reset at end of shot.
@@ -23,6 +22,10 @@ const MAGNUS_SQ_EPSILON := 1e-3
 ## Material physics configuration for this ball.
 @export var terrain_physics: TerrainPhysics
 
+## Coefficient of the linear curve that determines the minimum speed at
+## a given point in surface time below which the ball will be frozen.
+@export var surface_cull_coefficient: float = 0.2
+
 #@export var fluid_density := 1.225
 #@export var lift_coefficient := 0.05
 #@export var radius := 0.05
@@ -116,6 +119,7 @@ func _integrate_forces(state: PhysicsDirectBodyState3D) -> void:
 		_position_on_last_wake = global_position
 		_last_contact_normal = Vector3.UP
 		_shot_time_s = 0.0
+		_surface_time_s = 0.0
 		# TODO something's fucky here... I think this gets called once after the ball sleeps
 
 	if state.get_contact_count():
@@ -133,12 +137,19 @@ func _integrate_forces(state: PhysicsDirectBodyState3D) -> void:
 				primary_body = state.get_contact_collider_object(i)
 
 		_surface_terrain = Terrain.from_collision(global_position, primary_body)
-		_surface_time_s += state.step
+
+		var culling_speed_sq := pow(surface_cull_coefficient * _surface_time_s, 2) - 1
+		if linear_velocity.length_squared() < culling_speed_sq:
+			_manual_sleep()
 	else:
 		# Ball is in the air
 		_surface_terrain = Terrain.Type.NONE
 		_surface_time_s = 0.0
 
+	var params := terrain_physics.get_params(_surface_terrain)
+	angular_damp = params.angular_damp
+	linear_damp = params.linear_damp
+
 
 func _physics_process(delta: float) -> void:
 	# Simulate magnus effect
@@ -146,24 +157,9 @@ func _physics_process(delta: float) -> void:
 	if magnus.length_squared() > MAGNUS_SQ_EPSILON:
 		apply_central_force(magnus)
 
-	# Apply drag
-	var params := terrain_physics.get_params(_surface_terrain)
-	if linear_velocity.length() > params.linear_drag:
-		linear_velocity -= params.linear_drag * linear_velocity.normalized()
-	else:
-		linear_velocity = Vector3.ZERO
-	if angular_velocity.length() > params.angular_drag:
-		angular_velocity -= params.angular_drag * angular_velocity.normalized()
-	else:
-		angular_velocity = Vector3.ZERO
-
-	if linear_velocity.length_squared() < VELOCITY_SQ_EPSILON:
-		linear_velocity = Vector3.ZERO
-	if angular_velocity.length_squared() < VELOCITY_SQ_EPSILON:
-		angular_velocity = Vector3.ZERO
-
 	# Keep shot time
 	_shot_time_s += delta
+	_surface_time_s += delta
 
 
 func enter_zone(zone: BallZone) -> void:
@@ -194,11 +190,17 @@ func _on_sleeping_state_changed() -> void:
 		_awake = false
 
 
+func _manual_sleep() -> void:
+	freeze = true
+	linear_velocity = Vector3.ZERO
+	angular_velocity = Vector3.ZERO
+	manual_sleep_timer.start()
+
+
 func _on_collision(body: Node) -> void:
 	if is_sticky():
 		# Freeze physics as soon as we hit something
-		freeze = true
-		manual_sleep_timer.start()
+		_manual_sleep()
 
 	var terrain := Terrain.from_collision(global_position, body)
 	print_debug("Collision terrain: ", Terrain.Type.keys()[terrain])

src/equipment/balls/physics_ball/physics_ball.tscn

@@ -19,53 +19,53 @@
 
 [sub_resource type="Resource" id="Resource_casfi"]
 script = ExtResource("4_onl6o")
-linear_drag = 0.0
-angular_drag = 1.0
+linear_damp = 0.2
+angular_damp = 0.0
 
 [sub_resource type="Resource" id="Resource_3k63c"]
 script = ExtResource("4_onl6o")
-linear_drag = 0.0
-angular_drag = 0.0
+linear_damp = 0.0
+angular_damp = 0.0
 
 [sub_resource type="Resource" id="Resource_xf73q"]
 script = ExtResource("4_onl6o")
-linear_drag = 0.0
-angular_drag = 1.0
+linear_damp = 0.5
+angular_damp = 0.0
 
 [sub_resource type="Resource" id="Resource_nhn3l"]
 script = ExtResource("4_onl6o")
-linear_drag = 0.0
-angular_drag = 1.0
+linear_damp = 0.1
+angular_damp = 0.0
 
 [sub_resource type="Resource" id="Resource_m3wjo"]
 script = ExtResource("4_onl6o")
-linear_drag = 0.0
-angular_drag = 1.0
+linear_damp = 0.2
+angular_damp = 0.0
 
 [sub_resource type="Resource" id="Resource_h4rld"]
 script = ExtResource("4_onl6o")
-linear_drag = 0.0
-angular_drag = 1.0
+linear_damp = 0.1
+angular_damp = 0.0
 
 [sub_resource type="Resource" id="Resource_j6lib"]
 script = ExtResource("4_onl6o")
-linear_drag = 0.0
-angular_drag = 1.0
+linear_damp = 0.5
+angular_damp = 0.0
 
 [sub_resource type="Resource" id="Resource_7f7ql"]
 script = ExtResource("4_onl6o")
-linear_drag = 0.0
-angular_drag = 3.0
+linear_damp = 1.0
+angular_damp = 0.0
 
 [sub_resource type="Resource" id="Resource_pusmf"]
 script = ExtResource("4_onl6o")
-linear_drag = 1.0
-angular_drag = 10.0
+linear_damp = 4.0
+angular_damp = 0.0
 
 [sub_resource type="Resource" id="Resource_edkxb"]
 script = ExtResource("4_onl6o")
-linear_drag = 0.0
-angular_drag = 1.0
+linear_damp = 0.2
+angular_damp = 0.0
 
 [sub_resource type="Resource" id="Resource_3ngau"]
 script = ExtResource("3_52hui")

src/equipment/balls/physics_ball/terrain_physics/terrain_parameters.gd

@@ -1,5 +1,5 @@
 class_name TerrainParameters extends Resource
 ## Physical parameters for an individual terrain type.
 
-@export var linear_drag := 0.0
-@export var angular_drag := 0.0
+@export var linear_damp := 0.0
+@export var angular_damp := 0.0

src/ui/3d/projectile_arc/projectile_arc.gd

@@ -63,7 +63,8 @@ var _cached_vel: Vector3
 
 func set_ball(ball: GameBall) -> void:
 	global_position = ball.global_position
-	linear_damp = ball.linear_damp
+	linear_damp = ball.terrain_physics.default.linear_damp
+	print("using linear damp: ", linear_damp)
 
 
 func _process(_delta: float) -> void: