Skateboard Controller, RigidBody not working as expected

Unity Engine
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1

Hello,
I am a beginner game developer, recently trying to get into code.
I am working on a 3d platformer that is supposed to be kinda similar to crash bandicoot, but the player is riding a skateboard. While I’ve been trying to keep it basic, I keep running into problems I don’t know how to solve.
currently I am trying to use a Rigid Body controller, this is the closest I got to what I want:

{
    public float maxSpeed = 10f;
    public float acceleration = 5f; //rate of acceleration
    public float drag = 3f;
    public float turnSpeed = 120f;
    public float jumpForce = 5f;

    public float brakeSpeed = 15f;
    
    private float currentSpeed = 0f;
    private float moveInput;
    private float turnInput;

    private Rigidbody rb;
    

    void Start()
    {
            rb = GetComponent<Rigidbody>();
            rb.constraints = RigidbodyConstraints.FreezeRotationZ;
    }

    void Update()
    {
        GetDirectionalInput();
        Jump();
        HandleBraking();
      
    }

    void FixedUpdate()
    {
        
        MovePlayer();
    }

    void MovePlayer()
    {

        //calc acceleration
        if(moveInput > 0)
        {
            currentSpeed += acceleration * Time.deltaTime;
        }
        else if( moveInput <0)
        {
            currentSpeed -= acceleration * Time.deltaTime;
        }

        //apply drag when no input

        if(moveInput == 0)
        {
            currentSpeed -= drag * Time.deltaTime;
        }

        // clamp speed between 0 and max speed
        currentSpeed = Mathf.Clamp(currentSpeed, 0, maxSpeed);

        //calc movedirection based on input 
        Vector3 moveDirection = transform.forward * currentSpeed;
       
        rb.velocity = new Vector3(moveDirection.x, rb.velocity.y, moveDirection.z);
        

        if(turnInput != 0)
        {
            Quaternion turnRotation = Quaternion.Euler(0, turnInput * turnSpeed * Time.deltaTime, 0);
            rb.MoveRotation(rb.rotation * turnRotation);
        }
    }
    void GetDirectionalInput()
    {
        moveInput = Input.GetAxis("Vertical");
        turnInput = Input.GetAxis("Horizontal");
    }
    void HandleBraking()
    {
        if(Input.GetKey(KeyCode.Space))
        {
            currentSpeed -= brakeSpeed * Time.deltaTime;
        }

        //prevent backwards speed
        currentSpeed = Mathf.Max(currentSpeed,0);
    } 

    void Jump()
    {
        if(Input.GetKeyDown(KeyCode.J))
        {
            rb.AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
        }
      
    }  


}

basically, I can’t get the board to not rotate around the Z axis, unless the x axis is constrained too.
another problem is collisions in general. I don’t have complicated ramps in my game but even so, just any slope is enough for the rigid body to act kinda weird.
I thought about trying to do something with Character Controller, but that was also kinda awkward with slopes, and needed a lot more code to add proper physics. I also thought about using wheel colliders or something similar with raycasts for each wheel. but that might be over complicating it…

I would have added a video but I can’t because I am a new user apparently…
anyway, if anyone has any tips to improve this code, or any different approaches I would love some help.

thanks in advance!

2

A video might help to see what it looks like. For my racing game I locked z and X in the editor and only rotate y that might get rid of some of the weird movement on collisions.

3

Also add a physics material with zero friction to everything including player ramps walls and ground

4

Thank you for the reply! Unfortunately I can’t add a video because I’m a new user.
I tried locking X and Z rotation and it does help with some weird movement things but then how do you think I should handle ramps and slopes? How should I make the skateboard/player rotate in the same direction as the ramp or the slope?

5

You have to add a new layer called ground and use a raycast to determine if your on the ground and then rotate the player to match the ground rotation.

bool isOnground;
public LayerMask whatIsGround;
void GroundCheck()
{
Vector3 groundNormal;
Ray ray = new Ray(groundRay.position, -transform.up);
RaycastHit hitInfo;
isOnGround = Physics.Raycast(ray, out hitInfo, maxGroundDist, whatIsGround);
groundNormal = hitInfo.normal.normalized;
Vector3 projection = Vector3.ProjectOnPlane(transform.forward, groundNormal);
Quaternion rotation = Quaternion.LookRotation(projection, groundNormal);
rb.MoveRotation(Quaternion.Lerp(rb.rotation, rotation, Time.deltaTime * 10f));
}