// jumping
        if(Input.GetKeyDown(KeyCode.Space) && !jumping && isGrounded)
        {
            jumping = true;
            StartCoroutine(JumpRoutine());
        }


        // moving
        rb.AddForce(transform.forward * Input.GetAxis("Vertical") * speed);
        rb.AddForce(transform.right * Input.GetAxis("Horizontal") * speed);


        // check if can jump
        if (!isGrounded){
            rb.AddForce(-transform.up * gravity);
        }








    IEnumerator JumpRoutine()
    {
        rb.velocity = Vector2.zero;
        float timer = 0;

        while(Input.GetKey(KeyCode.Space) && timer < jumpTime)
        {
            //Add a constant force every frame of the jump
            rb.AddForce(transform.up*jumpStr);
            timer += Time.deltaTime;
            yield return null;
        }
        jumping = false;
    }