PSH: Player Controller

Understanding Vehicle Control

When working with vehicle physics in Godot, especially using VehicleBody3D, it’s important to understand how the vehicle reacts to player input (throttle, braking, and steering) and how these translate to actual movement in the scene.

For PSH I didn’t want to go for a full realistic control system for the game but not a very arcade-feel either so Godot’s VehicleBody3D provided a very good base for my vehicle controller.

In PVehicle3D, (Player Vehicle 3D) the player controller class, I started by defining how engine force, brake force, and steering should respond to player input. Godot’s vehicle body uses physics forces instead of directly setting velocity, so these inputs have to be processed each frame and applied to the body’s rigid physics system.

Core Control Logic

Acceleration and Braking

Acceleration is controlled through the engine force, which is applies torque to the wheels. When the player presses the throttle key (for example, W or an input axis), the script gradually increases the engine force up the limit based pm the RPM or gear ratio. Similarly, pressing the brake key applies a brake force that resists the wheel’s angular velocity.

The key takeaway is that you don’t instantly set the car’s speed — you simulate how the car’s engine builds power and how braking dissipates it. This gives a much more natural feel, especially in racing or driving simulators.

Steering

The front wheels are responsible for steering (depends on the car 2WD vs 4WD), and the turn amount is influenced by the car’s current speed. At lower speeds, you get full turning angles, but at higher speeds, the steering input is scaled down to prevent unrealistic sharp turns.

In code, this looks like adjusting the steering property of each “steering” wheel based on input and speed:

steering = steering_input * max_steering_angle

This mimics how real cars become harder to turn at high speeds.

Gear and Transmission Logic

One of the more advanced parts of PVehicle3D is the transmission system.
The car can operate in either manual or automatic mode. In manual, gear shifts depend on player input, while in automatic, the script determines when to shift up or down based on the RPM.

The gear ratio determines how much torque is transferred to the wheels. A lower gear gives more torque (good for acceleration), while a higher gear favors speed over torque.
This part of the system makes the car “feel” like it has an engine and transmission, not just a linear speed value.

RPM and Torque

Each frame, the script updates the engine RPM based on wheel speed and throttle.
When RPM exceeds a threshold, the script triggers a gear shift if the car is in automatic mode. The torque output is also linked to RPM, giving the feeling of an engine revving up and delivering power.

By tuning the max_rpm and gear ratios, you can drastically change how responsive or sluggish the vehicle feels this is something that’s super important when designing different car types (sports cars, trucks, off-road vehicles, etc.).

Wheel Grip and Stability

Another subtle but important factor is wheel grip. Each wheel in PVehicle3D has its own grip value, affecting how much traction it maintains when turning or accelerating.
Low grip leads to sliding or drifting behavior, while high grip gives precise control. By adjusting wet_grip or surface friction, you can simulate rain or dirt tracks quite easily.

Wrapping Up

The PVehicle3D script is still evolving, but starting from this base has given me a flexible, physics-driven vehicle system that feels grounded and fun to control. Rather than focusing on visuals, I’ve been exploring how to make the driving feel right by balancing speed, control, and realism.