Rolling rigidbody cube in Unity3D

Question

So in Unity3D I have a cube which is being controlled by a player(using arrows). Player can go wherever he wants with the cube. The problem is when I add rigidbody to the cube then it doesn't really go that smooth anymore, somehow at the end it just glitches. Tried to play a bit with torque , but that did not help or I do not understand yet clearly how to implement it correctly. This is the code I am using for the cube (it is written in JavaScript). Any help will be appreciated, even if you do not know the javascript an idea still counts. Thank you. Code :

private var ismoving : boolean = false;  
private var startY : float = 0;  
var cubeSpeed : float;  
var cubeSize : float;
var jumpHeight = 3.0;


function Update ()   
{  

    if (Input.GetKeyDown("up") && ismoving == false)  
    {  
        ismoving = true;  
        transform.Find("targetpoint").Translate(0, -cubeSize/2 , cubeSize/2);  
        StartCoroutine(DoRoll(transform.Find("targetpoint").position, Vector3.right, 90.0f,cubeSpeed));  

    }   
    if (Input.GetKeyDown("down") && ismoving == false)  
    {  
        ismoving = true;  
        transform.Find("targetpoint").Translate(0, -cubeSize/2, -cubeSize/2);  
        StartCoroutine(DoRoll(transform.Find("targetpoint").position, -Vector3.right, 90.0f,cubeSpeed));  
    }  
    if (Input.GetKeyDown("left") && ismoving == false)  
    {  
        ismoving = true;  
        transform.Find("targetpoint").Translate(-cubeSize/2, -cubeSize/2, 0);  
        StartCoroutine(DoRoll(transform.Find("targetpoint").position, Vector3.forward, 90.0,cubeSpeed));  
    }  
    if (Input.GetKeyDown("right") && ismoving == false)  
    {  
        ismoving = true;  
        transform.Find("targetpoint").Translate(cubeSize/2, -cubeSize/2, 0);  
        StartCoroutine(DoRoll(transform.Find("targetpoint").position, -Vector3.forward, 90.0f,cubeSpeed));     
    }  
        if (Input.GetKeyDown("space") && ismoving == false)  
    {  

    GetComponent.<Rigidbody>().AddForce(new Vector3(0, jumpHeight, 0), ForceMode.Impulse);
    } 



}  

function DoRoll (aPoint, aAxis, aAngle, aDuration) {    

 var tSteps = Mathf.Ceil(aDuration * 30.0);  
 var tAngle = aAngle / tSteps;  
 var pos : Vector3; 

  for (var i = 1; i <= tSteps; i++)   
  {   
    transform.RotateAround (aPoint, aAxis, tAngle);  
    yield WaitForSeconds(0.0033333);  
  }   


   transform.Find("targetpoint").position = transform.position;  


   pos = transform.position;  
   pos.y = startY;  
   transform.position = pos;  


   var vec = transform.eulerAngles;  
   vec.x = Mathf.Round(vec.x / 90) * 90;  
   vec.y = Mathf.Round(vec.y / 90) * 90;  
   vec.z = Mathf.Round(vec.z / 90) * 90;  
   transform.eulerAngles = vec;  


   ismoving = false;       
}

 function FixedUpdate () {

}  

Answer 1

It's likely not moving smoothly because you are modifying its position and rotation directly with its transform instead of using Rigidbody functions.

Once Rigidbody is attached to it, don't use transform.position = pos; or transform.eulerAngles = vec ;

Rigidbody.MovePosition , Rigidbody.MoveRotation , Rigidbody.AddForce , and Rigidbody.AddTorque are the functions you should be using.

Replace these in your DoRoll function

Rigidbody rb;
rb = GetComponent<Rigidbody>();

rb.MovePosition(pos);
rb.MoveRotation(Quaternion.Euler(vec));