效果(用鼠標(biāo)控制副物體旋轉(zhuǎn))：

image

通公式獲取圓的下一個(gè)坐標(biāo)位置：
x = vector3.x + r * cos(angle * PI / 180)
z = Vector3.z + r * sin(angle * PI /180)
源代碼:

public class Test : MonoBehaviour
{
    private Transform CylinderTranform;
    private float r;
    // Use this for initialization
    void Start()
    {
        CylinderTranform = GameObject.Find("Cylinder").transform;//獲取主物體坐標(biāo)
         r = Vector3.Distance(transform.position, CylinderTranform.position);//獲取主物體與跟隨物體距離，即半徑
    }

    float MouseX;
    // Update is called once per frame
    void Update()
    {
        transform.LookAt(CylinderTranform);
        MouseX += Input.GetAxis("Mouse X")*5;//獲取鼠標(biāo)位置*5
        //主物體X+半徑*cos(鼠標(biāo)位置*pi/180)
        var x = CylinderTranform.position.x + r*Mathf.Cos(-MouseX*Mathf.PI/180);
        var z = CylinderTranform.position.z + r*Mathf.Sin(-MouseX*Mathf.PI/180);
        transform.position = new Vector3(x, CylinderTranform.position.y, z);
    }
}