Unity2D - How to move AND rotate a gameobject around a circle in a 2D game?

user_12454030 0
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I'm trying to move and rotate some clouds around a target planet (which is just a circle at the moment). I got the movement down, but I am really struggling with the rotation part. I want it to rotate in proportion to where it is on the circle but I'm stuck trying to guesstimate the right numbers. Here is the code:

public class CloudMovement : MonoBehaviour
{
    public GameObject target;
    private float RotateSpeed = .05f;
    private float Radius = 1.0f;

    private Vector2 center;
    private float angle;

    private void Start()
    {
        center = target.transform.localPosition;
        Radius = target.transform.localScale.x / 1.5f;
    }

    private void Update()
    {

        angle = angle + RotateSpeed * Time.deltaTime;
        this.transform.Rotate (Vector3.forward * -angle * Time.deltaTime);

        Vector2 offset = new Vector2(Mathf.Sin(angle), Mathf.Cos(angle)) * Radius;
        this.transform.position = center + offset;
    }
}
unity3d c#
2 Answers
using UnityEngine;

public class CloudMovement : MonoBehaviour
{
    // X Y radius
    public Vector2 Velocity = new Vector2(1, 0); 

    // rotational direction
    public bool Clockwise = true;

    [Range(0, 5)] 
    public float RotateSpeed = 1f;
    [Range(0, 5)]
    public float RotateRadiusX = 1f;
    [Range(0, 5)]
    public float RotateRadiusY = 1f;        

    private Vector2 _centre;
    private float _angle;

    private void Start()
    {
        _centre = transform.position;
    }

    private void Update()
    {
        _centre += Velocity * Time.deltaTime;    
        _angle += (Clockwise ? RotateSpeed : -RotateSpeed) * Time.deltaTime;    
        var x = Mathf.Sin(_angle) * RotateRadiusX;
        var y = Mathf.Cos(_angle) * RotateRadiusY;    
        transform.position = _centre + new Vector2(x, y);
    }

    void OnDrawGizmos()
    {
        Gizmos.DrawSphere(_centre, 0.1f);
        Gizmos.DrawLine(_centre, transform.position);
    }
}

Edit Option 2: RotateAround

A more recent option, baked into Unity -- you can also try RotateAround function

Vector3 point = new Vector3(10,0,0);
Vector3 axis =  new Vector3(0,0,1);
transform.RotateAround(point, axis, Time.deltaTime * 10);

transform.RotateAround() takes a Vector3 PointAxis&float Angle` in degrees.

The Axis is rotational direction.

Same thing, with a working sample from here

public class CloudMovement : MonoBehaviour {

 public float speed;
 public Transform target;

 private Vector3 zAxis = new Vector3(0, 0, 1);

 void FixedUpdate () {
     transform.RotateAround(target.position, zAxis, speed); 
 }
}
user_60851930

You can! By continuously changing the x scale! call this function in the update void

public void Rotate()
    {
        if (transform.localScale.x <= -1)
        {
            rotationBool = true;
        }
        if (transform.localScale.x >= 1)
        {
            rotationBool = false;
        }
        if (rotationBool == false)
        {
            Vector3 scaleChange = new Vector3(0.01f, 0f, 0f);
            transform.localScale -= scaleChange;
        }
        if (rotationBool == true)
        {
            Vector3 scaleChange = new Vector3(0.01f, 0f, 0f);
            transform.localScale += scaleChange;
        }
    }
user_153133240
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