VehicleBody3D in Godot – Complete Guide

Excitement is just one line of code away when you dive into the world of video game creation with Godot 4, especially when it comes to adding dynamic elements like vehicles to your games. In this tutorial, we’re going to get under the hood of the VehicleBody3D class, a powerful tool that brings cars and other vehicles to life in your 3D environments. If you’ve ever dreamed of creating vibrant game worlds with vehicles that obey the laws of physics, or simply want to add that extra bit of interactivity and fun to your game, this class is for you. So, buckle up and get ready to drive into the nitty-gritty of simulating vehicles in Godot 4.

What Is VehicleBody3D?

VehicleBody3D is a specialized RigidBody3D that simulates the intricate behavior of a car. It’s built on the principle of raycast vehicles that most physics engines use. This doesn’t just add realism to the movement and interaction of vehicles, but it also takes care of many complexities behind the scenes, making it accessible for beginners.

What Is It For?

The purpose of VehicleBody3D is to deliver an authentic driving experience within a 3D game environment. It’s designed to work in tandem with other nodes like CollisionShape3D for the vehicle’s body and VehicleWheel3D for each of its wheels, letting players control the braking, acceleration, and steering just like a real car.

Why Should I Learn It?

Understanding and utilizing the VehicleBody3D class is essential for anyone interested in game development where vehicle mechanics play a role. By learning this component, you’ll gain the ability to craft rich and interactive gameplay experiences that can captivate players. As with any complex system, getting the hang of VehicleBody3D will boost your development skills and open up new creative possibilities for your projects.

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Setting Up Your VehicleBase Scene

Before we delve into the coding nitty-gritty, we need to set up the base scene for your vehicle. In Godot 4, this means creating a scene with a VehicleBody3D node as the root. To kickstart the process, here’s how you would set up a functional VehicleBody3D:

extends VehicleBody3D

func _ready():
    add_wheel("FrontLeft", Vector3(1.5, -1.0, 2.5))
    add_wheel("FrontRight", Vector3(-1.5, -1.0, 2.5))
    add_wheel("BackLeft", Vector3(1.5, -1.0, -2.5))
    add_wheel("BackRight", Vector3(-1.5, -1.0, -2.5))

func add_wheel(name: String, position: Vector3):
    var wheel = VehicleWheel3D.new()
    wheel.name = name
    wheel.position = position
    add_child(wheel)

This will set the ground for our car model to have four wheels positioned accordingly in a typical car layout.

Configuring the Vehicle’s Wheels

Once you’ve added the wheels, you’d want to configure them for realistic movement and physics interactions. Let’s start by setting up the front wheels to be steerable.

func _ready():
    # ... previous setup code
    get_node("FrontLeft").set_steering(true)
    get_node("FrontRight").set_steering(true)

Then, you must adjust the suspension and friction to make the wheels react realistically.

func _ready():
    # ... previous setup code
    for wheel in get_children():
        wheel.suspension_stiffness = 5.88
        wheel.suspension_travel = 0.3
        wheel.friction_slip = 10.5
        wheel.mass = 20

This setup will affect how your wheels behave under different driving conditions, providing that realistic car physics feel.

Adding Engine and Steering Functions

Functionality for movement comes next. We need to make our ‘car’ move forward and allow the player to control the steering. Here’s a basic implementation:

var engine_force = 0
var brake = 0
var steering = 0

func _physics_process(delta):
    engine_force = 500 * Input.get_action_strength("ui_up")
    brake = 500 * Input.get_action_strength("ui_down")
    steering = 5 * Input.get_action_strength("ui_left") - 5 * Input.get_action_strength("ui_right")

    apply_steer_and_engine_forces()

func apply_steer_and_engine_forces():
    get_node("FrontLeft").engine_force = engine_force
    get_node("FrontRight").engine_force = engine_force
    get_node("FrontLeft").brake = brake
    get_node("FrontRight").brake = brake
    get_node("FrontLeft").steering = steering
    get_node("FrontRight").steering = steering

The ‘ui_up’, ‘ui_down’, ‘ui_right’, and ‘ui_left’ actions are to be set in the Input Map in your project settings, allowing player inputs to control the vehicle.

Applying Gravity and Damping

For a finishing touch on the basics, it’s crucial to tweak your vehicle’s gravity and damping for a realistic weight and momentum feel. This is how you might adjust such settings:

func _ready():
    # ... previous setup code
    gravity = 9.8  # Adjusting the gravity to Earth's gravity.
    linear_damp = 0.5  # Damping the movement to simulate air resistance.

This bit of code ensures your vehicle doesn’t float away or stop too abruptly.

Now, with these configurations, you’ve laid the foundational code required to create a basic vehicle simulation in Godot 4. Stay tuned for the upcoming parts where we’ll enhance our vehicle with more advanced features and controls. Remember that tweaking these parameters and understanding how they interact is key to creating the perfect driving experience in your game. We at Zenva encourage you to experiment with values and see the effects firsthand!As we continue to rev up our vehicle’s capabilities, we delve deeper into advanced controls and physics to enrich the gameplay experience. These enhancements will give your virtual vehicle a more nuanced and realistic behavior.

Implementing Acceleration and Deceleration

Smooth acceleration and deceleration are crucial for a natural driving feel. We implement this by modifying engine force and braking depending on whether the player is accelerating or not.

var max_engine_force = 1000
var max_brake_force = 250

func _physics_process(delta):
    var acceleration = Input.get_action_strength("ui_up") - Input.get_action_strength("ui_down")
    engine_force = acceleration > 0 ? max_engine_force * acceleration : 0
    brake = acceleration < 0 ? max_brake_force * -acceleration : 0

    apply_steer_and_engine_forces()

This will make sure that the vehicle gradually picks up speed and comes to a halt in a realistic manner.

Tuning the Differential, Gears, and Steering Response

A car’s differential and gears play a significant role in its handling. We simulate this by adjusting the differential and gear ratios of the VehicleBody3D.

func _ready():
    # ... previous setup code
    differential_ratio = 3.42
    gear_ratios = [3.166, 1.882, 1.296, 0.972, 0.738]

To improve steering responsiveness, we can interpolate the steering value over time.

var steering_increment = 0.04

func _physics_process(delta):
    # ... previous acceleration and braking code
    var target_steering = (Input.get_action_strength("ui_left") - Input.get_action_strength("ui_right")) * max_steering_angle
    steering = lerp(steering, target_steering, steering_increment)

This smooths the transition between steering angles, offering a more fluid steering experience.

Adding Skid Marks and Tire Sounds

For an immersive experience, visual and auditory feedback like skid marks and tire sounds can be added.

func _process(delta):
    var skid_value = calculate_skid_value() # A function to determine skid intensity based on wheel spin and slip
    if skid_value > skid_threshold:
        leave_skid_mark()
        play_tire_squeal_sound()

This level of detail further draws the player into the game, making every tight corner or sudden stop more dramatic.

Adjusting for Off-road and On-road Dynamics

To ensure your vehicle performs differently on various terrains, you may want to adjust the grip and suspension dynamics accordingly.

func _physics_process(delta):
    var on_road = is_on_road()  # A function to determine if the vehicle is on the road
    for wheel in get_children():
        if on_road:
            wheel.friction_slip = road_friction
        else:
            wheel.friction_slip = off_road_friction

Players will have to adjust their driving strategy based on the terrain, adding depth to the gameplay.

With these advancements, your vehicle is not just a moving object but a full-fledged simulation of driving dynamics. At Zenva, we’re all about taking learning to the next level by applying these concepts. Remember, these code snippets should serve as a starting point for you to experiment with building your own vehicle physics that suit the style and feel of your game. There’s a lot more under the bonnet of vehicle simulation, and we encourage you to explore it as you craft your game world. Happy coding!Continuing our journey in creating a highly interactive vehicle in Godot 4, let’s take your game’s realism and fun to the next level with advanced physics manipulations and fine-tuning. The script enhancements we’re going to discuss cover aspects like weight distribution, air resistance, and more!

Weight Distribution and Center of Mass

How your vehicle balances and distributes weight affects handling dramatically. To simulate this, we can adjust the center of mass to a lower point to simulate a lower gravity center, which is common in sports cars for better stability.

func _ready():
    # ... previous setup code
    mass = 1500 # Set the mass of your vehicle
    center_of_mass = Vector3(0, -0.5, 0) # Lowering the center closer to ground improves stability

This makes the vehicle less likely to tip over during tight turns and adds to the feeling of weight when maneuvering.

Simulating Air Resistance

Air resistance (drag) can significantly affect the vehicle’s top speed and acceleration. Let’s add a simple drag force that increases with the square of speed:

var drag_coefficient = 0.4257 # Aerodynamic drag coefficient, typical for a car

func _physics_process(delta):
    # ... previous logic
    var forward_velocity = global_transform.basis.z.normalized().dot(linear_velocity)
    var drag_force_magnitude = drag_coefficient * forward_velocity * forward_velocity
    apply_central_force(-global_transform.basis.z * drag_force_magnitude)

Playing with drag coefficients can reflect different vehicle shapes and sizes, echoing real-world physics.

Downforce and Lift

In racing games, downforce keeps a car glued to the track at high speeds, while lift can lead to a loss of control. Here’s how you can simulate downforce:

var downforce = 200.0 # The amount of downforce applied

func _physics_process(delta):
    # ... previous logic
    var downforce_magnitude = downforce * engine_force
    apply_central_force(Vector3(0, -downforce_magnitude, 0))

This additional force will be felt during high speeds, keeping the car stable on the road.

Traction Control

To help prevent wheel slip, we can simulate traction control, adjusting engine force based on the wheel’s grip:

var wheel_slip_threshold = 0.2 # Threshold at which we consider the wheel to be slipping

func _physics_process(delta):
    # ... previous logic
    for wheel in get_children():
        if wheel.is_in_contact() and wheel.get_skidinfo() > wheel_slip_threshold:
            engine_force *= 0.5 # Reduces engine force to mitigate slipping

Traction control is especially important when dealing with surfaces like ice or loose gravel.

Anti-lock Braking System (ABS)

An anti-lock braking system prevents the wheels from locking up and helps maintain grip with the road during braking. Here’s a simple implementation:

var abs_threshold = 0.8 # Threshold for activating ABS

func _physics_process(delta):
    # ... previous logic
    for wheel in get_children():
        if wheel.is_in_contact() and wheel.get_skidinfo() > abs_threshold:
            brake *= 0.5 # Pulsing the brakes to simulate ABS

ABS can be a critical feature in action-packed racing games where precision braking matters.

By now, you have a strong foundation to simulate many aspects of real-world driving physics in Godot 4. However, game development is as much about feeling as it is about physics. Fine-tuning each of these systems is the key to creating an engaging and believable driving experience. At Zenva, we understand that diving deep into these intricate systems can seem daunting, but it’s also incredibly rewarding. Your players will feel the difference in each turn and throttle push. So start your engines, and let’s build something amazing together!

Where to Go Next in Your Godot Game Development Journey

Now that you’ve dipped your toes into the world of vehicle physics with Godot 4, you may be wondering, “What’s next?” The road to mastering game development is long and full of fascinating detours, and we’re here to guide you every step of the way. Our Godot Game Development Mini-Degree is the perfect next destination for anyone looking to expand their knowledge and skill set. This comprehensive suite of courses takes you from understanding the basics to building your own cross-platform games, covering a broad range of topics that will equip you with the expertise you need to create compelling gameplay experiences.

Whether you’re just starting out or looking to build upon your existing foundation, we’ve meticulously designed our curriculum to be learner-friendly and flexible. We welcome you to browse our full collection of Godot courses and choose the path that piques your curiosity. With hands-on projects and a plethora of skills to acquire, Zenva is your ally in transitioning from beginner to professional game developer. So, take the leap and keep fueling your passion for learning with us – your game development adventure is just getting started!

Conclusion

Embarking on this journey through vehicle physics in Godot 4, you’ve unlocked a new realm of possibilities for your games. Remember, the depth of your understanding directly influences the thrill your game can offer. Whether it’s the rush of a perfectly executed drift or the strategic play around a treacherous terrain, the knowledge you’ve gained here sets the stage for you to create those memorable moments. And with Zenva’s Godot Game Development Mini-Degree, you’re never alone on this path of discovery and creation. Let this be just the start of a thrilling adventure in game development, with Zenva by your side as your trusty guide and resource. So go on, take these skills for a spin, and see where your imagination leads you in the fantastical world of game creation!

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