From c1426ddcc0e89ea67d9f41aed78911dfdda888f0 Mon Sep 17 00:00:00 2001
From: Wheelbarrow <bingoperson001@gmail.com>
Date: Sat, 26 Jul 2025 15:29:11 -0400
Subject: [PATCH] changed to use max static friction

---
 car.gd   |  2 +-
 wheel.gd | 43 +++++++++++++++++++++++++++++++++++--------
 2 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/car.gd b/car.gd
index 11dfa16..147ef46 100644
--- a/car.gd
+++ b/car.gd
@@ -53,7 +53,7 @@ func steer(delta: float) -> void:
 		front_left.rotation.y = -outer_angle
 
 func apply_air_resistance() -> void:
-	var force: Vector3 = air_resistance * linear_velocity * linear_velocity.length()
+	var force: Vector3 = -air_resistance * linear_velocity * linear_velocity.length()
 	apply_force(force, center_of_mass)
 	DebugDraw3D.draw_arrow(
 		to_global(center_of_mass),
diff --git a/wheel.gd b/wheel.gd
index c270006..9d0fef5 100644
--- a/wheel.gd
+++ b/wheel.gd
@@ -9,25 +9,31 @@ extends RayCast3D
 @export var suspension_rest_length: float = 0.1
 @export var suspension_stiffness: float = 30_000
 @export var suspension_damping: float = 2000
+@export_group("Friction")
+@export var static_friction: float = 1.1
 
 var car: Car
+var acceleration: Vector3
 var _last_velocity: Vector3
 
 func _ready() -> void:
 	target_position *= suspension_rest_length + wheel_radius
-	$"RX-Wheel".rotate_y(PI if flipped else 0.0)
+	if flipped: $"RX-Wheel".rotate_y(PI)
 
 func set_new_car(new_car: Car) -> void:
 	car = new_car
 	# Little bit freaky but we put up with it
 	_last_velocity = car.get_velocity_at_point(get_collision_point())
 
-func _physics_process(_delta: float) -> void:
+func _physics_process(delta: float) -> void:
+	var velocity: Vector3 = car.get_velocity_at_point(get_collision_point())
+	acceleration = velocity - _last_velocity / delta
 	force_raycast_update()
 	
 	apply_suspension_force()
 	apply_rolling_resistance()
-	apply_engine_force()
+	apply_friction_force()
+	
 	_last_velocity = car.get_velocity_at_point(get_collision_point())
 
 func apply_suspension_force() -> void:
@@ -71,25 +77,46 @@ func apply_rolling_resistance() -> void:
 	car.apply_force(force, car.to_local(get_collision_point()))
 	DebugDraw3D.draw_arrow(
 		arrow_tail,
-		arrow_tail + force,
+		arrow_tail + force / 250,
 		Color.ORANGE,
 		.2
 	)
 
-func apply_engine_force() -> void:
+func apply_friction_force() -> void:
 	if not on_drivetrain: return
 	if not is_colliding(): return
 	
 	var forwards: Vector3 = -global_basis.z
+	var backwards: Vector3 = global_basis.z
+	var normal: Vector3 = get_collision_normal()
+	
+	var total_weight: Vector3 = car.mass * car.get_gravity()
+	var wheel_to_com: float = abs(
+		forwards.dot(car.center_of_mass) - \
+		forwards.dot(car.to_local(get_collision_point()))
+	)
+	var weight: Vector3 = wheel_to_com / car.wheelbase * total_weight
+	var normal_force: Vector3 = -weight
+	
+	# Intern please fix
+	var surface_static_friction: float = 1
+	var static_friction_coeff: float = static_friction * surface_static_friction
+	var maximum_static_friction: float = static_friction_coeff *  normal_force.length()
 	
 	var torque: float = car.get_torque_per_wheel()
-	var force: Vector3 = forwards * torque / wheel_radius
+	var applied_force: Vector3 = backwards * torque / wheel_radius
+	#Restricts applied force to plane parralel to surface
+	applied_force -= normal * applied_force.dot(normal)
+	
+	var friction_force: Vector3 = Vector3.ZERO
+	if applied_force.length() <= maximum_static_friction:
+		friction_force = -applied_force
 	
 	var arrow_tail: Vector3 = to_global(get_wheel_center())
-	car.apply_force(force, car.to_local(get_collision_point()))
+	car.apply_force(friction_force, car.to_local(get_collision_point()))
 	DebugDraw3D.draw_arrow(
 		arrow_tail,
-		arrow_tail + force / 250,
+		arrow_tail + friction_force / 250,
 		Color.BLUE,
 		.2
 	)