Unity UI alphaHitTestMinimumThreshold on RawImage

I am trying to make a Hole in the Unity UI and I wanted to move the Hole with the UV Rect from RawImage, however, I can´t seem to be able to set the alphaHitTestMinimumThreshold for the RawImage, which means I cant click through the Hole.
Is there any way to achieve this?

In the Image below, I would like to be able to click through the hole the left top button and not be able to click the right top button. The only very unclean solution I thought of would be making a huge Image with a Hole and putting it in the UI Image texture and moving the whole GameObject, thats why I wanted to ask if there is any other cleaner solution.

Thanks in advance for any advice.

 

I also tried writing a shader which creates a transparent hole which i can move around, however, the clicks also didn´t register through the cutout.

 

Quite late, but for google:

Code (CSharp):

1.  
2. using System;
3. using UnityEngine;
4. using UnityEngine.EventSystems;
5. using UnityEngine.UI;
6.  
7. /*
8. * RawImage doesn't have alphaHitTestMinimumThreshold, (which let's you avoid raycasting transparent pixels)
9. * This class act's as alphaHitTestMinimumThreshold replacement for RawImages by overriding raycast's default behaviour
10. * THE IMAGE TEXTURE MUST HAVE READ/WRITTING IN IT'S SETTINGS
11. * Stolen from https://github.com/Hengle/GrassWateringSimulator2019/blob/master/Grass%20Watering%20Simulator%202019/Assets/HTC.UnityPlugin/ViveInputUtility/Examples/4.Teleport/Scripts/ImageAlphaRaycastFilter.cs
12. */
13.  
14. [RequireComponent(typeof(RawImage))]
15. public class ImageAlphaRaycastFilter : UIBehaviour, ICanvasRaycastFilter
16. {
17.     [NonSerialized]
18.     private RawImage m_rawImage;
19.  
20.     public float alphaHitTestMinimumThreshold = 1;
21.  
22.     protected RawImage rawImage {
23.         get { return m_rawImage ?? (m_rawImage = GetComponent<RawImage>()); }
24.     }
25.  
26.     public virtual bool IsRaycastLocationValid(Vector2 screenPoint, Camera eventCamera) {
27.         if (alphaHitTestMinimumThreshold <= 0) { return true; }
28.         if (alphaHitTestMinimumThreshold > 1) { return false; }
29.  
30.         var texture = rawImage.mainTexture as Texture2D;
31.  
32.         Vector2 local;
33.         if (!RectTransformUtility.ScreenPointToLocalPointInRectangle(rawImage.rectTransform, screenPoint, eventCamera, out local)) {
34.             return false;
35.         }
36.  
37.         var rect = rawImage.GetPixelAdjustedRect();
38.  
39.         // Convert to have lower left corner as reference point.
40.         local.x += rawImage.rectTransform.pivot.x * rect.width;
41.         local.y += rawImage.rectTransform.pivot.y * rect.height;
42.  
43.         // normalize
44.         local = new Vector2(local.x / rect.width, local.y / rect.height);
45.  
46.         try {
47.             return texture.GetPixelBilinear(local.x, local.y).a >= alphaHitTestMinimumThreshold;
48.         } catch (UnityException e) {
49.             Debug.LogError("Using alphaHitTestMinimumThreshold greater than 0 on Graphic whose sprite texture cannot be read. " + e.Message + " Also make sure to disable sprite packing for this sprite.", this);
50.             return true;
51.         }
52.     }
53. }