I'm trying to get my cube to only jump on the ground but my if statement isn't working

Question

public Rigidbody rb;
public bool cubeIsOnTheGround = true;
public float speed = 10;

Vector3 direction;

// Start is called before the first frame update
void Start()
{
    rb.GetComponent<Rigidbody>();
}

// Update is called once per frame
void Update()
{
    Vector3 input = new Vector3(Input.GetAxisRaw("Horizontal"), 0, Input.GetAxisRaw("Vertical"));
    direction = input.normalized;
    
    if (Input.GetButtonDown("Jump"))
    {
        rb.AddForce(new Vector3(0, 5, 0), ForceMode.Impulse);
    }

    if (cubeIsOnTheGround == true)
    {
        if (Input.GetButtonDown("Jump"))
        {
            rb.AddForce(new Vector3(0, 5, 0), ForceMode.Impulse);
            cubeIsOnTheGround = false;
        }
    }
}

void FixedUpdate()
{
    rb.position += direction * speed * Time.deltaTime;
}

void OnCollisionEnter(Collision collision)
{
    if (collision.gameObject.CompareTag("Ground"))
    {
        cubeIsOnTheGround = true;
    }
}

The if statemnt boolIsOnTheGround is not working. What I'm trying to do is check whether the cube is on the ground so I kno when you can jump. The cube just bounces infinitely by pressing space.

Answer 1

In your code you have two if-blocks where you jump:

    if (Input.GetButtonDown("Jump"))
    {
        rb.AddForce(new Vector3(0, 5, 0), ForceMode.Impulse);
    }

    if (cubeIsOnTheGround == true)
    {
        if (Input.GetButtonDown("Jump"))
        {
            rb.AddForce(new Vector3(0, 5, 0), ForceMode.Impulse);
            cubeIsOnTheGround = false;
        }
    }

The first if-block does not check cubeIsOnTheGround , so it will jump as long as the jump button is pressed. If you remove the first block this behavior should stop.