Added engine force, air resistance, and rolling resistance

also added debug draw 3d addon

car.gd

@@ -1,6 +1,10 @@
 class_name Car
 extends RigidBody3D
 
+## X axis is RPM, Y axis is torque in NM
+@export var torque_curve: Curve
+@export var air_resistance: float = .3
+
 @export_group("Steering")
 ## Maximum angle of imaginary wheel at center front of the car
 @export var max_steer_angle: float = 30
@@ -18,11 +22,15 @@ extends RigidBody3D
 @onready var track: float = front_right.position.distance_to(front_left.position)
 
 var current_steer_angle: float = 0
+var rpm: float = 0
+
+func _ready() -> void:
+	for wheel: Wheel in wheels:
+		wheel.set_new_car(self)
 
 func _physics_process(delta: float) -> void:
 	steer(delta)
-	for wheel: Wheel in wheels:
-		wheel.apply_forces(self)
+	apply_air_resistance()
 
 func steer(delta: float) -> void:
 	var steer_input = Input.get_axis("Steer Right", "Steer Left")
@@ -44,6 +52,25 @@ func steer(delta: float) -> void:
 		front_right.rotation.y = -inner_angle
 		front_left.rotation.y = -outer_angle
 
-##Point argument is in local space
+func apply_air_resistance() -> void:
+	var force: Vector3 = air_resistance * linear_velocity * linear_velocity.length()
+	apply_force(force, center_of_mass)
+	DebugDraw3D.draw_arrow(
+		to_global(center_of_mass),
+		to_global(center_of_mass) + force,
+		Color.YELLOW,
+		.2
+	)
+
+##Point argument is in global space
 func get_velocity_at_point(point: Vector3) -> Vector3:
-	return linear_velocity + angular_velocity.cross(point - center_of_mass)
+	return linear_velocity + angular_velocity.cross(to_local(point) - center_of_mass)
+
+## Returns torque in NM, per wheel on the drive train
+func get_torque_per_wheel() -> float:
+	var is_powered: Callable = func (wheel: Wheel) -> bool: return wheel.on_drivetrain
+	var powered_wheel_count: int = wheels.filter(is_powered).size()
+	if 0 < powered_wheel_count:
+		var engine_torque: float = Input.get_action_strength("Accelerate") * torque_curve.sample_baked(rpm)
+		return engine_torque / powered_wheel_count
+	return 0.0