VehicleWheel3D in Godot – Complete Guide

Have you ever dreamed of creating a game with exhilarating car races or realistic vehicle simulations? Whether it’s the roar of the motors or the thrill of speed, bringing vehicles to life in a game is a joy many developers seek. In the realm of 3D game development, simulating vehicle dynamics is complex but incredibly rewarding. With the latest version of Godot, you have the power to simulate the intricate behavior of vehicles through the VehicleWheel3D node. In this tutorial, we’ll delve into the nuts and bolts of the VehicleWheel3D class and get your digital wheels spinning on the tracks of the Godot engine.

What is VehicleWheel3D?

VehicleWheel3D is a class in the Godot 4 engine designed to represent a wheel of a vehicle in a 3D environment. This node, when added as a child to a VehicleBody3D, simulates the physics of a wheel, including its interactions with the terrain, steering movements, and forces like braking and acceleration. It stands out as a specialized tool within your gamedev toolkit for crafting vehicle behaviors without getting bogged down in low-level physics.

What is it for?

The primary function of the VehicleWheel3D node is to simulate the wheel segment of vehicle physics. Each wheel can exert force on the body of the vehicle, respond to user input for steering, and apply braking forces. Understanding and utilizing this node is essential for creating a vehicle’s realistic and interactive driving experience in your game.

Why Should I Learn It?

Learning to implement VehicleWheel3D can elevate your game’s interactivity and realism significantly, which is often a marker of quality in game design. For budding developers, mastering the VehicleWheel3D class means gaining a deeper understanding of physics in game development. For the experienced programmer, it’s an opportunity to create more intricate vehicle mechanics, possibly leading to more engaging gameplay. Regardless of your skill level, patrolling the avenues of VehicleWheel3D offers insight and control over one of the most dynamic elements in 3D game creation – vehicles.

In the following sections, we’ll gear up with coding examples and practical guidance to get you started on implementing VehicleWheel3D in your own Godot projects. Buckle up, as we embark on a journey into the realm of game development where your creative potential is the only speed limit!

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Setting Up the Vehicle with VehicleBody3D

Before delving into the VehicleWheel3D, it’s crucial to set up the main vehicle body. Let’s start by creating a VehicleBody3D node in a new scene, which will act as the core of our vehicle. Remember, all VehicleWheel3D nodes must be child nodes of a VehicleBody3D to function correctly.

var vehicle_body = VehicleBody3D.new()
add_child(vehicle_body)

Now, let’s define the basic properties of our vehicle body – its weight and center of mass. Adjust these parameters to fit the specific feel you want for your vehicle. You can set the weight using the mass property, and you can adjust the center of mass by modifying the center_of_mass property.

vehicle_body.mass = 1600
vehicle_body.center_of_mass = Vector3(0, -1, 0)

Once your vehicle body is configured, you can proceed to add wheels to it.

Adding and Configuring Wheels

Attach wheels to your vehicle by creating instances of VehicleWheel3D and adding them as children to the VehicleBody3D. Here’s how you can add a single wheel:

var front_left_wheel = VehicleWheel3D.new()
vehicle_body.add_child(front_left_wheel)
front_left_wheel.translation = Vector3(1, -1, 2.5)

Repeat this step for all the wheels your vehicle needs, placing them accordingly. Remember to adjust the translation for each wheel to position them correctly relative to the body.

For the wheels to work correctly, you’ll need to set up several properties for each, such as the suspension settings:

front_left_wheel.suspension_rest_length = 0.1
front_left_wheel.wheel_radius = 0.3
front_left_wheel.suspension_travel = 0.2
front_left_wheel.suspension_stiffness = 5
front_left_wheel.damping_compression = 0.3
front_left_wheel.damping_relaxation = 0.5

This setup defines how much the suspension can travel, its stiffness, and the damping rates. Fine-tuning these will affect how the wheel interacts with the ground and responds to terrain changes.

Steering and Motor Configuration

Steering and motor action are controlled by adjusting the respective properties of the VehicleWheel3D. Let’s set the front wheels to be steerable:

front_left_wheel.steering = true

And for a simple car, only the front or rear wheels (not both) should typically pull the car forward, so let’s make the front wheels act as the motor:

front_left_wheel.engine_force = true

You can now control the steering and engine force through your game’s input actions. Here is a sample code snippet to steer the wheels based on the player’s input:

var steer_angle = 40 # Max steering angle in degrees
var current_engine_force = 1500

func _process(delta):
    var turn_input = Input.get_action_strength("turn_right") - Input.get_action_strength("turn_left")
    front_left_wheel.steering_angle = steer_angle * turn_input
    front_right_wheel.steering_angle = steer_angle * turn_input

    if Input.is_action_pressed("accelerate"):
        front_left_wheel.engine_force = current_engine_force
        front_right_wheel.engine_force = current_engine_force
    else:
        front_left_wheel.engine_force = 0
        front_right_wheel.engine_force = 0

This will allow players to control the steering and acceleration of the vehicle using their inputs.

Braking the Vehicle

Finally, let’s add the ability to brake. Use the brake property on the VehicleWheel3D instances to slow the vehicle down. We’ll check for a brake input, and when it’s pressed, apply the brake:

var brake_force = 2000 # Adjust this for stronger or weaker brakes

func _process(delta):
    var brake_input = Input.is_action_pressed("brake")
    for wheel in vehicle_body.get_children():
        if wheel is VehicleWheel3D:
            wheel.brake = brake_force if brake_input else 0

Using this approach, all of your vehicle’s wheels will apply the braking force simultaneously when the player presses the brake input.

With these foundational examples, you have a basic vehicle setup in Godot that can steer, accelerate, and brake. You can now expand on these basics to introduce more complex vehicle behaviors and refine the control system for a more enjoyable driving experience in your game.

Advanced Vehicle Dynamics

Once you have the basic setup of your vehicle with steering, acceleration, and braking, you can enhance the realism of your car simulation with advanced dynamics. We can add features like differential steering, traction control, and even a simple gearbox model.

Differential Steering

Differential steering allows the wheels on the same axle but on opposite sides of the vehicle to rotate at different speeds. This is crucial for smooth turns. To simulate differential steering, you might modify the engine force based on the steering angle.

func _process(delta):
    var differential_rate = 0.2 # This can be adjusted to simulate different differential behaviors
    var engine_force_modifier = 1.0 - abs(front_left_wheel.steering_angle) * differential_rate
    front_left_wheel.engine_force = current_engine_force * engine_force_modifier
    front_right_wheel.engine_force = current_engine_force * (1.0 - engine_force_modifier)

Traction Control

Traction control prevents the wheels from slipping when accelerating, especially on loose or slippery surfaces. To simulate traction control, you would modulate the engine force based on the wheel’s traction.

func _process(delta):
    for wheel in vehicle_body.get_children():
        if wheel.is_engine_force and wheel.is_slipping():
            wheel.engine_force *= 0.5  # Reduce engine force to regain traction

This simple example halves the engine force on any wheel that is slipping, mimicking traction control’s behavior.

Simple Gearbox Model

A gearbox can also be simulated, allowing for speed changes through ‘gears’. Let’s create a basic gearbox model with a few set gear ratios and a method to shift up and down.

var current_gear = 1
var gear_ratios = [0, 3.2, 2.1, 1.4, 1.0, 0.8]

func shift_up():
    current_gear += 1
    if current_gear >= gear_ratios.size():
        current_gear = gear_ratios.size() - 1

func shift_down():
    current_gear -= 1
    if current_gear <= 0:
        current_gear = 1

func update_engine_force():
    current_engine_force = base_engine_force * gear_ratios[current_gear]
    for wheel in vehicle_body.get_children():
        if wheel.is_engine_force:
            wheel.engine_force = current_engine_force

You can call the `shift_up` or `shift_down` functions based on the vehicle’s speed and engine RPMs, then update the engine force with the new gear ratio.

Adjusting Damping for Realistic Suspension

Lastly, fine-tuning the suspension can lead to a more realistic ride, especially when your vehicle is moving over various terrain types. By modifying damping based on the vehicle’s current speed, the suspension can react differently when moving quickly over bumpy terrain versus slowly over a smooth road.

func _process(delta):
    for wheel in vehicle_body.get_children():
        if wheel is VehicleWheel3D:
            var current_speed = vehicle_body.get_linear_velocity().length()
            wheel.damping_compression = lerp(min_compression, max_compression, current_speed / top_speed)
            wheel.damping_relaxation = lerp(min_relaxation, max_relaxation, current_speed / top_speed)

By dynamically adjusting compression and relaxation values, we can simulate how the suspension hardens at high speeds, which gives the vehicle a more connected feel to the road.

These are just a few ways you can advance the vehicle physics in your game using Godot’s VehicleWheel3D node. Experimenting with these elements and understanding their impact on your vehicle’s behavior is key to creating an engaging and lifelike driving experience. Remember, getting these settings just right will take time and a lot of trial and error. Happy coding and may your games always move forward smoothly!Let’s now focus on simulating various terrains and how they can affect our vehicle’s handling. We’ll also add in odometer functionality to keep track of the distance traveled, and we’ll look at ways to tweak the friction between the wheel and the ground for different surfaces.

Simulating Different Terrains

Different terrains can have a significant impact on how a vehicle accelerates, turns, and stops. In Godot, you can simulate this by adjusting the friction and damping of the wheels based on the surface the vehicle is currently over.

To demonstrate, let’s assume your game distinguishes between asphalt, dirt, and sand, with each behaving differently under the wheels:

var terrain_type = "asphalt"  # This would normally be determined by the surface below the vehicle

func _process(delta):
    match terrain_type:
        "asphalt":
            set_wheel_friction(1.0)
        "dirt":
            set_wheel_friction(0.7)
        "sand":
            set_wheel_friction(0.4)

func set_wheel_friction(value):
    for wheel in vehicle_body.get_children():
        if wheel is VehicleWheel3D:
            wheel.friction_slip = value

By calling `set_wheel_friction` with different values, you simulate how each wheel interacts with different surfaces. Friction slip determines how much grip the wheel has on the surface it’s on, affecting handling characteristics.

Adding an Odometer

To add an odometer to our vehicle, we’ll need to keep track of the distance each wheel has rotated and sum this up to get the total distance the vehicle has traveled.

var distance_traveled = 0.0

func _process(delta):
    var wheel_distance = 0.0
    for wheel in vehicle_body.get_children():
        if wheel is VehicleWheel3D:
            wheel_distance += wheel.rotation_degrees * wheel.wheel_radius
    distance_traveled += wheel_distance * delta

This simple script updates `distance_traveled` every frame, by adding up the distance each wheel has theoretically rolled during that frame. `wheel.rotation_degrees` gives us the rotation of the wheel in degrees, which when multiplied by `wheel.wheel_radius` contributes to the distance calculation.

Tweaking Wheel Friction

We can take the concept of wheel friction further by not only adjusting it for different terrains but by also having it decrease as the wheels lose traction or increase when driving techniques such as drifting are employed.

func apply_drift():
    var drift_factor = 0.5  # Higher means more drift
    for wheel in vehicle_body.get_children():
        if wheel is VehicleWheel3D and wheel.steering:
            wheel.friction_slip += drift_factor

func correct_grip():
    for wheel in vehicle_body.get_children():
        if wheel is VehicleWheel3D:
            wheel.friction_slip = max(wheel.friction_slip - 0.1, our_default_friction)

In `apply_drift`, we increase the friction slip momentarily to simulate the loss of grip during a drift. `correct_grip` might be called when the vehicle is back under control, slowly returning the friction slip back to its default state.

Implementing Wheel Spin and Skid Marks

For an extra touch of realism, let’s simulate wheel spin when the vehicle is accelerating hard or when it loses traction. We can even add visual effects like skid marks.

func _physics_process(delta):
    for wheel in vehicle_body.get_children():
        if wheel.is_engine_force and wheel.get_skidinfo() > some_threshold:
            emit_skid_mark(wheel.global_transform.origin)

func emit_skid_mark(position):
    # Here you'd instantiate a particle system or decal at the wheel's location
    var skid_mark_instance = skid_mark_scene.instance()
    skid_mark_instance.global_transform.origin = position
    add_child(skid_mark_instance)

The `get_skidinfo()` function is a hypothetical method that returns a value based on the current friction state of the wheel. If it exceeds a certain threshold, which indicates the wheel is slipping, it triggers the emission of a skid mark at the wheel’s location.

Every one of these code examples shows an evolutionary step in enhancing the simulation of vehicle dynamics within the Godot environment. Incrementally adding these details will build up a complex and nuanced simulation, providing players with a rich and believable driving experience. Always tweak and test these parameters based on the specific needs of your game to find the perfect balance between playability and realism.

As you can see, working with VehicleWheel3D opens up endless possibilities for creating custom vehicle behaviors in Godot. At Zenva, we encourage explorative learning and experimentation, bolstering your knowledge through hands-on experience. Now it’s your turn to take these principles and steer your own course through the exciting track of game development!

Continuing Your Game Development Journey with Zenva

Great work diving into the mechanics of the VehicleWheel3D node in Godot! Now that you’ve got a taste of simulating realistic vehicle dynamics, you might be wondering, “Where do I go from here?” The thrilling path of game development is filled with continuous learning, and we’re here to support your growth every step of the way.

If you’re inspired to keep expanding your game development skills, consider exploring our Godot Game Development Mini-Degree. It’s a comprehensive collection of courses that delve into building cross-platform games with Godot 4. You’ll explore various aspects of game development, from using assets to mastering the GDScript programming language, and from controlling gameplay flow to creating complex combat systems. Suitable for beginners and experienced developers alike, our curriculum offers projects that will help you build your own games and develop a solid portfolio.

For an even broader understanding of what Godot has to offer and to fine-tune your game-making abilities, check out our full range of Godot courses. Whether you’re a novice coder or a professional looking to upskill, Zenva provides an extensive selection of courses that cater to your desire to create and innovate. Start learning with us today, and unlock the potential to turn your game development dreams into reality.

Remember, the journey doesn’t end here. With Zenva, you can go from beginner to professional. Let us be a part of your story, and let’s code, create and conquer the world of game development together!

Conclusion

Embarking on the adventure of 3D game development with Godot is an exciting journey, and mastering elements like the VehicleWheel3D node can rev up your games to new heights. With the wheels now set in motion, remember that practice and continual learning are the fuels that will drive your projects forward. Whether creating high-speed racers or serene simulation experiences, your newly acquired skills will set the stage for unlimited creative exploration.

Don’t let the learning journey end here. Keep your development engine running by exploring our Godot Game Development Mini-Degree. Accelerate your growth and stay at the forefront of game development with Zenva, your dedicated co-pilot in the world of coding and game creation. Let’s keep coding, let’s keep creating, and let’s make those game dreams come to life!

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