Steer

Lesson 2 of 20 in Coddy's Godot Game: Neon Circuit course.

Now the car turns. Input.get_axis reads two keys at once: -1 for the first, 1 for the second, 0 for none:

var steer := Input.get_axis("move_left", "move_right")

A real car only turns while it rolls, and turns less when it barely moves. So the turn is scaled by the speed. velocity.dot(forward) is how fast the car goes the way it points (negative when it rolls backwards):

var speed := velocity.dot(forward)
rotation += steer * turn_speed * delta * clampf(absf(speed) / 90.0, 0.0, 1.0) * signf(speed + 0.01)

clampf(absf(speed) / 90.0, 0.0, 1.0) grows from 0 when standing to 1 at 90 pixels a second. signf flips the turn when rolling backwards, as a real car does. In Godot a bigger rotation turns clockwise, so Right adds to it.

Challenge

Easy

Add @export var turn_speed := 3.2 under max_speed.
Read steer under throttle.
After forward, work out speed.
After the velocity grows, turn the car with the line above.

Try it yourself

extends Node2D

@export var accel := 260.0
@export var max_speed := 200.0

var velocity := Vector2.ZERO


func _physics_process(delta: float) -> void:
	var throttle := Input.get_action_strength("move_up")

	var forward := Vector2.RIGHT.rotated(rotation)

	velocity += forward * throttle * accel * delta
	velocity = velocity.limit_length(max_speed)
	position += velocity * delta
	$Exhaust.emitting = throttle > 0.0