Unity Canvas不同模式下实现UI追随物体_unity ui跟随物体

在Canvas不同渲染模式（RenderMode）下实现UI跟随3D物体功能。

Screen Space-Overlay

利用WorldToScreenPoint()将物体的世界坐标转换成屏幕坐标,然后更新UI的坐标：

1.UI跟随3D物体

public class UIFollowObj : MonoBehaviour {
 
 public GameObject obj;//3D物体
 
 public  RectTransform rectUI;//UI元素
 
 public Vector2 offset;//偏移量
 
 void Start(){
 
  offset = new Vector3(0, 0, 0);
 }
 void Update () {
  Vector2 screenPos=Camera.main.WorldToScreenPoint(obj.transform.position);
  rectUI.position = screenPos + offset;
 }
}

2.UI跟随鼠标

    public Vector3 offset;
 
    void Update()
    {
     gameObject.transform.position = Input.mousePosition+ offset;
    }

Screen Space-Camera

RectTransformUtility.ScreenPointToLocalPointInRectangle换算出UI元素在Canvas的2D坐标:

1.UI跟随3d物体

    public Camera UI_Camera;//UI相机
    public RectTransform image;//UI元素
    public Canvas ui_Canvas;
    void UpdateUIPosition()
    {
        Vector2 PlayerScreen = Camera.main.WorldToScreenPoint(Player.transform.position);
        Vector2 mouseUGUIPos = new Vector2();
        bool isRect = RectTransformUtility.ScreenPointToLocalPointInRectangle(ui_Canvas.transform as RectTransform, PlayerScreen, UI_Camera, out mouseUGUIPos);
 
        Debug.Log(mouseUGUIPos);
        if (isRect)
        {
            image.anchoredPosition = mouseUGUIPos;
        }
    }

2.UI跟随鼠标（此处我的分辨率是1920*1080）

  //Canvas
    public RectTransform canvasRectTra;
    //需要跟随的UI
    public RectTransform imageRectTra;
    //UI相机
    public Camera mainCamera;
 
 
    void Update()
    {
        SetImagePosition(Input.mousePosition+new Vector3(1920/2,1080/2,0));
    }
 
    /// <summary>
    /// 参数为鼠标点击坐标
    /// </summary>
    /// <param name="v3"></param>
    private void SetImagePosition(Vector3 v3)
    {
        Vector2 imagePanelV2 = new Vector2();
 
        if (RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRectTra, v3, mainCamera, out imagePanelV2))
        {
 
            imageRectTra.anchoredPosition = imagePanelV2;
        }
    }