Unity ugui interaction (new ideas)

I came across a question in the Q & A these two days ： What we want to achieve is to give a location , Then interact with UI, At first I misunderstood , Then I thought again , It's natural to think of rays + Collision body . When you open the editor , Think about it again , In this way, we not only need to change the canvas RenderMode, Also give all that you want to interact UI Make a collision body , There seems to be some trouble .UGUI Isn't it your own set of radiographic tests , You can try it .
Then the first edition wrote this

 void Start()
    {
    
        mPointer = transform.GetComponent<RectTransform>();
        eventSystem = EventSystem.current;
        pointerEventData = new PointerEventData(eventSystem);
    }
    // Update is called once per frame
    void Update()
    {
    
        PointerSimulation();
    }
    void PointerSimulation()
    {
    
        pointerEventData.position = mPointer.anchoredPosition;
        eventSystem.RaycastAll(pointerEventData, uiRaycastResultCache);
        Debug.Log($"{
      uiRaycastResultCache.Count}");
    }

Run the test , Find out debug Has always been a 0, Think about it. ,pointerEventData.position We usually use Input.MousePosition, The screen space coordinate system used by the mouse is based on the lower left corner of the screen (0,0) Dot , So modify the one used to simulate the mouse UI The relative layout of .

Here's for the novice , Do you want us to use UGUI Please make sure your canvas has Graphic Raycaster Components 、UI above raycast target It's on .


The next step is to follow UI Interaction , The first reaction in my mind is to interact UI Hang him up Item Little script , Then the management class gets all Item perform event wait , Then it soon fell , It still feels like trouble . Finally, I checked , Learned a new API:ExecuteEvents.Execute
It can be PointerEventData Pass it to the specified object and trigger the transmitted assignment UI Event type , therefore , The script of the second version is as follows

    void PointerSimulation()
    {
    
        pointerEventData.position = mPointer.anchoredPosition;
        eventSystem.RaycastAll(pointerEventData, uiRaycastResultCache);
        Debug.Log($"{
      uiRaycastResultCache.Count}");
        if (uiRaycastResultCache.Count > 0)
        {
    
            for (int i = 0; i < uiRaycastResultCache.Count; i++)
            {
    
                eventSystem.SetSelectedGameObject(uiRaycastResultCache[i].gameObject);
                ExecuteEvents.Execute(uiRaycastResultCache[i].gameObject, pointerEventData, ExecuteEvents.pointerClickHandler);
            }
        }
    }

When UI Radiographic detection UI after , Stored in list in , Then traverse list, Set the hit object to the selected state , Then simulate triggering a mouse click . Of course, we can do more , such as ：

 void Drag()
    {
    
        pointerEventData.position = Input.mousePosition;
        // Radiographic testing ui
        eventSystem.RaycastAll(pointerEventData, uiRaycastResultCache);
        Debug.Log($"{
      uiRaycastResultCache.Count}");
        if (uiRaycastResultCache.Count > 0)
        {
    
                eventSystem.SetSelectedGameObject(uiRaycastResultCache[0].gameObject);
                if (Input.GetMouseButtonDown(0))
                {
    
                    ExecuteEvents.Execute(uiRaycastResultCache[0].gameObject, pointerEventData, ExecuteEvents.pointerDownHandler);

                }
                if (Input.GetMouseButton(0))
                {
    
                    ExecuteEvents.Execute(uiRaycastResultCache[0].gameObject, pointerEventData, ExecuteEvents.dragHandler);
                }
                if(Input.GetMouseButtonUp(0))
                {
    
                    ExecuteEvents.Execute(uiRaycastResultCache[0].gameObject, pointerEventData, ExecuteEvents.pointerUpHandler);

                }
    
        }
    }

You can put you UI Write down all the time types involved in it , There will be no error if it is not used . Here I simply write a button triggered and UI Drag and drop （UI You need to write the script of dragging specific logic by yourself , I won't let it go ）