Unity2D - 如何在 2D 游戲中圍繞圓圈移動和旋轉游戲對象？

Question

我正在嘗試圍繞目標行星（目前只是一個圓圈）移動和旋轉一些雲。 我把運動放下了，但我真的在旋轉部分掙扎。 我希望它根據它在圓圈上的位置按比例旋轉，但我一直在試圖猜測正確的數字。 這是代碼：

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;
    }
}

Answer 1

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);
    }
}

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編輯選項 2 ： RotateAround

一個更新的選項，融入到 Unity 中——你也可以嘗試RotateAround函數

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

transform.RotateAround()以度為單位采用Vector3 Point Axis & float Angle`。

軸是旋轉方向。

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同樣的事情， 這里有一個工作樣本

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); 
 }
}

Answer 2

你可以！ 通過不斷改變 x 比例！ 在更新無效時調用此函數

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;
        }
    }