Make a rolling ball in 2D

I need to make a ball rotate in Z-axis
This is the code i am trying to use,
but it wants me to use Vector2 instad of Vector3 And Vector2 cannot rotate in Z-axis.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Movement : MonoBehaviour
6. {
7.  
8.     public float speed = 5;
9.  
10.     void Update()
11.     {
12.  
13.         if (Input.GetKey(KeyCode.A))
14.         {
15.             Rigidbody2D.AddForce(Vector3.back * speed);
16.         }
17.         if (Input.GetKey(KeyCode.D))
18.         {
19.             Rigidbody2D.AddForce(Vector3.forward * speed);
20.         }
21.  
22.     }
23.  
24. }
25.  

 

I think you want to roll ball in its local x axis, as x axis is Right axis, while z axis is Forward axis.
Assuming you want to roll toward moving direction?

 

like in this video but only left or right
https://unity3d.com/learn/tutorials/projects/roll-ball-tutorial/introduction-roll-ball

 

you got on your rigid body myRigidBody2D.AddForce
Why not use myRigidBody2D.AddTorqe ?
Alternatively, you can apply myRigidBody2D.angularVelocity

There is nothing wrong with having Vector3.
Why your concerns?

 

Ok, Thanks for helping
I use Microsoft Visual studio what suggested Vector2.

 

I f you stay with Vector3, you will have always more flexibility, which doesn't hurt at all. But you can potentially reuse bits in future, if you want to go for full 3D, rather 2D. Also good learning case.

I wonder, where MS VS suggested that. Have you link by any chance.
Either way, I suggest stick with Unity guide lines. Unless they suggested Vector2

 

I dont have links...
But i seem to get " cannot convert from 'unityengine.vector3' to 'float' "
from (Vector3.back * speed) and (Vector3.forward * speed)
Btw i changed Addforce to Addtorque.

 

Thats fine.

multiplying vector by value gives you vector.
If you want axis, then use vector.x for example.