Extra: Boost

In the hud.tscn scene: Add a ColorRect node under the main Control node.

• Rename it to Boost and change it's size to an upright rectangle on the right side of the screen.
• Change the colour to transparent(ish) dark green.
• Add another ColorRect node under the main ColorRect Boost node. Rename this to BoostIndicator.
• Add BoostIndicator to the labels global group (in Node > Signals).
• Add a Label as a child of the Boost node and set the text to Boost. Set the scale to 1.5.

Bind a 'Boost' to your Space Bar in the Settings > Input Map.

Inside our car.gd, add in these changes.

var boost_multiplier = 1.5 # Factor to increase acceleration during boost
var boost_duration = 2.0 # Boost lasts for 2 seconds
var boost_cooldown = 5.0 # 5 seconds cooldown between boosts
var is_boosting = false # Tracks if boost is active
var boost_timer = 0.0 # Timer to track boost duration
var cooldown_timer = 0.0 # Timer for boost cooldown
var boost_rect_size = 370 # Change this to your rectangles current size!
var boost_indicator

func _ready() -> void:
    # (exisiting code)
    boost_indicator = labels.filter(func(label): return label.name == "BoostIndicator")[0]

func _process(delta: float) -> void:
    # Handle boost activation with space bar
    if Input.is_action_just_pressed("Boost") and cooldown_timer <= 0.0:
        start_boost()

    # Update timers if boosting or in cooldown
    if is_boosting:
        boost_timer -= delta
        # the lerp function maps the timer to the boost bar.
        boost_indicator.size.y = lerp(0, boost_rect_size, boost_timer / 2.0)
        if boost_timer <= 0.0:
            end_boost() # End boost when timer runs out
    elif cooldown_timer > 0.0:
        cooldown_timer -= delta
        boost_indicator.size.y = lerp(boost_rect_size, 0, cooldown_timer / 5.0)
        boost_indicator.color = Color('ca7566a5') # transparent red
    else:
        boost_indicator.color = Color('caff66a5') # transparent green

func _physics_process(delta: float):
    # steering & speed physics
    # (exisiting code)
    var acceleration = Input.get_axis("Backward", "Forward")
    # Add a check if the car is boosting between acceleration declaration
    # and before the rpm declaration
    if is_boosting:
        acceleration *= boost_multiplier # Apply boost multiplier
    
    var rpm = abs($BackLeftWheel.get_rpm())
    # (exisiting code)

func start_boost():
    is_boosting = true # Activate boosting
    boost_timer = boost_duration # Set the boost duration timer
    cooldown_timer = boost_cooldown # Set the cooldown timer

func end_boost():
    is_boosting = false # Deactivate boosting