Unity UGUI坐标和世界坐标转化

上代码:

 public Vector3 GetUIToWordPos(GameObject uiObj)
 {
     Vector3 ptScreen = RectTransformUtility.WorldToScreenPoint(Camera.main, uiObj.transform.position);
     ptScreen.z = 0;
     ptScreen.z = Mathf.Abs(Camera.main.transform.position.z - transform.position.z);
     Vector3 ptWorld = Camera.main.ScreenToWorldPoint(ptScreen);
     return ptWorld;
 }

 public Vector3 GetWorldToUIPos(GameObject worldObj, GameObject uiObj)
 {
     Vector3 originOff;  // 当前UI系统(0,0)点 相对于屏幕左下角(0, 0)点的偏移量
     originOff = new Vector3(-Screen.width / 2, -Screen.height / 2);
     Vector3 position = Camera.main.WorldToScreenPoint(worldObj.transform.position) + originOff;
     position.z = 0;
     RectTransform rt = uiObj.transform.GetComponent();
     Vector2 pivot = rt.pivot;
     switch (pivot.x)
     {
         case 1:
             position.x += rt.sizeDelta.x / 2;
             break;
         case 0:
             position.x -= rt.sizeDelta.x / 2;
             break;
     }
     switch (pivot.y)
     {
         case 1:
             position.y += rt.sizeDelta.y / 2;
             break;
         case 0:
             position.y -= rt.sizeDelta.y / 2;
             break;
     }
     return position;
 }

使用方式举例

public GameObject cube;
public GameObject image; 
cube.transform.position = GetUIToWordPos(image); 
image.transform.localPosition = GetWorldToUIPos(cube, image); 

参考链接
Unity UGUI坐标与世界坐标转换
Unity C# 3D世界坐标转2D屏幕坐标