extends VehicleBody3D
class_name Car
@export var STEER_SPEED := 1.0
@export var steer_curve: Curve = preload("res://assets/cars/kenney_sedan/steer_curve.tres")
var steer_target := 0.0
const trail_scene = preload("res://scenes/trail.tscn")
@export var MAX_ENGINE_FORCE := 4000.0
@export var MAX_BRAKE_FORCE := 35.0
@export var reverse_ratio := -2.5
@export var final_drive_ratio := 3.38
@export var max_engine_rpm := 8000.0
@export var gear_shift_time = 0.3
@export var power_curve: Curve = preload("res://assets/cars/kenney_sedan/power_curve.tres")
@onready var body_mesh := $body as MeshInstance3D
@onready var checkpoint_sound := $checkpoint as AudioStreamPlayer
@onready var wheels: Array[VehicleWheel3D] = [$bl as VehicleWheel3D, $br as VehicleWheel3D, $fl as VehicleWheel3D, $fr as VehicleWheel3D]
var particles: Array[GPUParticles3D] = []
signal shifted
var gear_ratios: Array[float] = [ 5 ]
var current_gear := 0 # -1 reverse, 0 = neutral, 1 - 6 = gear 1 to 6.
var clutch_position := 1 # 0.0 = clutch engaged
var gear_timer := 0.0
var throttle := 0.0
var skids: Array[Array]
func ratio() -> float:
match current_gear:
0: return 0
-1: return reverse_ratio
_: return gear_ratios[current_gear - 1]
func downforce(force: float):
apply_force(basis * Vector3(0,-force,0), Vector3(0,1.4,2.5))
func is_on_ground() -> bool:
return wheels.all(func(whl: VehicleWheel3D): return whl.is_in_contact() != null)
func is_not_on_ground() -> bool:
return wheels.any(func(whl: VehicleWheel3D): return !whl.is_in_contact())
func reset() -> void:
steering = 0
throttle = 0
engine_force = 0
brake = 15
set_physics_process(false)
func _ready() -> void:
for whl in wheels:
particles.append(whl.get_node(^"particles"))
skids.append([{active = false}]) # performance and complexity hack
randomize()
func kph():
return (3 * PI * wheels[0].wheel_radius * rpm()) / 25;
# calculate the RPM of our engine based on the average of the wheels
func rpm() -> float:
var sum := 0.0
for wheel in wheels:
sum += abs(wheel.get_rpm())
return sum / 4
func steer(to: float) -> void:
if (abs(to) < 0.05):
to = 0.0
else:
to = -steer_curve.sample_baked(-to) if to < 0.0 else steer_curve.sample_baked(to)
steer_target = lerpf(steer_target, to, 10 * get_physics_process_delta_time())
## virtual
func shift_down() -> bool:
return false
## virtual
func shift_up() -> bool:
return false
func _process_gear_inputs(delta: float):
if gear_timer > 0.0:
gear_timer = max(0.0, gear_timer - delta)
clutch_position = 0
else:
if shift_down() and current_gear > -1:
current_gear = current_gear - 1
gear_timer = gear_shift_time
clutch_position = 0
shifted.emit()
elif shift_up() and current_gear < gear_ratios.size():
current_gear = current_gear + 1
gear_timer = gear_shift_time
clutch_position = 0
shifted.emit()
else:
clutch_position = 1
func _process(delta: float):
_process_gear_inputs(delta)
func limit(delta: float) -> void:
linear_damp = max((.5 * delta) * (kph() - 400), 0) if kph() > 400 else 0.0
angular_damp = max(5 * (angular_velocity.length_squared() - 45), 0) if angular_velocity.length_squared() > 45 else 0.0
func _physics_process(delta: float):
downforce(5)
var power_factor := power_curve.sample_baked(clampf(rpm() / max_engine_rpm, 0.0, 1.0))
if current_gear == -1:
engine_force = throttle * power_factor * reverse_ratio * final_drive_ratio * MAX_ENGINE_FORCE * clutch_position
elif current_gear > 0 and current_gear <= gear_ratios.size():
engine_force = throttle * power_factor * gear_ratios[current_gear - 1] * final_drive_ratio * MAX_ENGINE_FORCE * clutch_position
else:
engine_force = 0.0
steering = -clampf(steer_target, -.7, .7)
body_mesh.rotation.z = lerp(body_mesh.rotation.z, clampf(((-steering * .2) * linear_velocity.length_squared() / 685.0) + randf_range(-0.05,0.05), -.4, .4), 10 * delta)
limit(delta)
for i in 4:
particles[i].emitting = wheels[i].get_skidinfo() < (.2 if i > 2 else .99) and wheels[i].is_in_contact() and kph() > 30
if particles[i].emitting:
particles[i].amount = clampf(ceil(150 * (1 - wheels[i].get_skidinfo())) * 1 if i > 2 else 8, 0, 150)
var init := false
if !skids[i][-1].active:
init = true
skids[i].append(trail_scene.instantiate() as Trail3D)
get_parent().add_child(skids[i][-1])
(skids[i][-1] as Trail3D).add(wheels[i].global_position - Vector3(0, .661, 0))
elif skids[i][-1].active:
skids[i][-1].active = false
func start() -> void:
brake = 0
set_physics_process(true)