Input.mousePosition

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Test_Mouse : MonoBehaviour {

    public GameObject go;

	// Use this for initialization
	void Start () {
		
	}
	
	// Update is called once per frame
	void Update () {
        Debug.Log("    "+Input.mousePosition);
        //go.GetComponent<RectTransform>().sizeDelta = new Vector2(Input.mousePosition.x, Input.mousePosition.y);
        //go.GetComponent<RectTransform>().localPosition = new Vector3(Input.mousePosition.x, Input.mousePosition.y,0);
        //Camera.main.WorldToScreenPoint(Input.mousePosition);
        go.GetComponent<RectTransform>().position = new Vector3(Input.mousePosition.x, Input.mousePosition.y, 0);
    }
}
 

因為

Input.mousePosition

go.GetComponent<RectTransform>().position = new Vector3(Input.mousePosition.x, Input.mousePosition.y, 0);

注意這裡 的Image的 位置不能是 localPosition，會產生 偏差。

正確的是position。

你會發現，是Image圖片的 中點，跟隨 滑鼠進行移動。

----------------------------------------

go.GetComponent<RectTransform>().sizeDelta【參考文章1，2】

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Test_Mouse : MonoBehaviour {

    public GameObject go;

	// Use this for initialization
	void Start () {
		
	}
	
	// Update is called once per frame
	void Update () {
        Debug.Log("    "+Input.mousePosition);
        //go.GetComponent<RectTransform>().sizeDelta = new Vector2(Input.mousePosition.x, Input.mousePosition.y);
        //go.GetComponent<RectTransform>().localPosition = new Vector3(Input.mousePosition.x, Input.mousePosition.y,0);
        //Camera.main.WorldToScreenPoint(Input.mousePosition);
        go.GetComponent<RectTransform>().position = new Vector3(Input.mousePosition.x- (go.GetComponent<RectTransform>().sizeDelta.x/2),
            Input.mousePosition.y - (go.GetComponent<RectTransform>().sizeDelta.y / 2)
            , 0);
    }
}
 

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Test_Mouse : MonoBehaviour {

    public GameObject go;

	// Use this for initialization
	void Start () {
		
	}
	
	// Update is called once per frame
	void Update () {
        Debug.Log("    "+Input.mousePosition);
        //go.GetComponent<RectTransform>().sizeDelta = new Vector2(Input.mousePosition.x, Input.mousePosition.y);
        //go.GetComponent<RectTransform>().localPosition = new Vector3(Input.mousePosition.x, Input.mousePosition.y,0);
        //Camera.main.WorldToScreenPoint(Input.mousePosition);
        go.GetComponent<RectTransform>().position = new Vector3(Input.mousePosition.x + (go.GetComponent<RectTransform>().sizeDelta.x/2),
            Input.mousePosition.y + (go.GetComponent<RectTransform>().sizeDelta.y / 2)
            , 0);
    }
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Test_Mouse : MonoBehaviour {

    public GameObject go;

	// Use this for initialization
	void Start () {
		
	}
	
	// Update is called once per frame
	void Update () {
        Debug.Log("    "+Input.mousePosition);
        //go.GetComponent<RectTransform>().sizeDelta = new Vector2(Input.mousePosition.x, Input.mousePosition.y);
        //go.GetComponent<RectTransform>().localPosition = new Vector3(Input.mousePosition.x, Input.mousePosition.y,0);
        //Camera.main.WorldToScreenPoint(Input.mousePosition);
        go.GetComponent<RectTransform>().position = new Vector3(Input.mousePosition.x + (go.GetComponent<RectTransform>().sizeDelta.x/2),
            Input.mousePosition.y - (go.GetComponent<RectTransform>().sizeDelta.y / 2)
            , 0);
    }
}

----------------------------------------

參考文章：

1.UGUI之RectTransform知識點 圖解
http://www.manew.com/thread-41633-1-1.html
(出處: -【遊戲蠻牛】-ar增強現實,虛擬現實,unity3d,unity3d教程下載首選u3d,unity3d官網)

2.

ugui在執行時改變RectTransform的大小

3.

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