CarTest/Assets/Scripts/WheelController.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using TMPro;

public class WheelController : MonoBehaviour
{
    [SerializeField] private WheelCollider frontRightWheelCollider;
    [SerializeField] private WheelCollider frontLeftWheelCollider;
    [SerializeField] private WheelCollider rearRightWheelCollider;
    [SerializeField] private WheelCollider rearLeftWheelCollider;

    //wheel meshes
    [SerializeField] private Transform frontRightWheel;
    [SerializeField] private Transform frontLeftWheel;
    [SerializeField] private Transform rearRightWheel;
    [SerializeField] private Transform rearLeftWheel;

    [SerializeField] private TMP_Text flRpmLabel;
    [SerializeField] private TMP_Text frRpmLabel;
    [SerializeField] private TMP_Text rlRpmLabel;
    [SerializeField] private TMP_Text rrRpmLabel;

    public float acceleration = 500f;
    public float breakingForce = 300f;
    [Range(15f,75f)] public float maxTurnAngle;

    private float currentAcceleration = 0f;
    private float currentBrakeForce = 0f;
    private float currentTurnAngle = 0f;

    private void Update() {
        flRpmLabel.text = getWheelRPM(frontLeftWheelCollider).ToString();
        frRpmLabel.text = getWheelRPM(frontRightWheelCollider).ToString();
        rlRpmLabel.text = getWheelRPM(rearLeftWheelCollider).ToString();
        rrRpmLabel.text = getWheelRPM(rearRightWheelCollider).ToString();
    }

    private float getWheelRPM(WheelCollider wheel){
        return wheel.rpm;
    }

    private void FixedUpdate() {
        //forward reverse input
        currentAcceleration = acceleration * Input.GetAxis("Vertical");

        //breaking input
        if(Input.GetKey(KeyCode.Space)){
            currentBrakeForce = breakingForce;
        }else{
            currentBrakeForce = 0f;
        }

        //apply acceleration to front wheels| (this determines which wheel drive is the car (fwd, awd, rwd))
        ApplyAccelerationToWheel(rearRightWheelCollider, currentAcceleration);
        ApplyAccelerationToWheel(rearLeftWheelCollider, currentAcceleration);

        //break applies to all four wheels
        ApplyBrakeToWheel(frontLeftWheelCollider, currentBrakeForce);
        ApplyBrakeToWheel(frontRightWheelCollider, currentBrakeForce);
        ApplyBrakeToWheel(rearLeftWheelCollider, currentBrakeForce);
        ApplyBrakeToWheel(rearRightWheelCollider, currentBrakeForce);

        //steering
        currentTurnAngle = maxTurnAngle * Input.GetAxis("Horizontal"); //getting steering input
        ApplyStreering(currentTurnAngle);

        //update wheel meshes
        UpdateWheel(frontLeftWheelCollider, frontLeftWheel);
        UpdateWheel(frontRightWheelCollider, frontRightWheel);
        UpdateWheel(rearLeftWheelCollider, rearLeftWheel);
        UpdateWheel(rearRightWheelCollider, rearRightWheel);
    }

    private void ApplyStreering(float streeringAngle){
        frontLeftWheelCollider.steerAngle = streeringAngle;
        frontRightWheelCollider.steerAngle = streeringAngle;
    }

    private void ApplyBrakeToWheel(WheelCollider wheel, float breakForce){
        wheel.brakeTorque = breakForce;
    }

    private void ApplyAccelerationToWheel(WheelCollider wheel, float acceleration){
        wheel.motorTorque = acceleration;
    }

    private void UpdateWheel(WheelCollider collider, Transform wheel){
        //get collider state
        Vector3 position;
        Quaternion rotation;

        collider.GetWorldPose(out position, out rotation); //puts it into position and rotation

        //set wheel state
        wheel.position = position;
        wheel.rotation = rotation;
    }
}