Interact with UI button through Render Texture

I'm looking for a solution on how to interact with UI buttons and scrolls through a Render Texture.

I have found this example, and it works great for objects like cubes and spheres, but it doesn't work with UI.
https://answers.unity.com/questions/1018336/is-there-a-way-to-click-on-a-render-texture-to-sel.html

Hopefully someone knows how to implement this with a UI canvas.

 

I know it is a super long shot but.... did you ever figure this out? I have a setup that because of certain pixel processing requires a stacked camera be sent through a render texture before final output. I NEED the UI to exist behind the render texture.

Basically I have a UICAM which renders the UI, it is in the stack with the Base "GameCam". GameCam renders to a render texture and then the RenderCam is an orthographic camera pointing to a plane with the render texture applied to it.

I _KNOW_ its a scuffed setup but I can't find another way to both force low resolution pixel perfection on a UI, while ALSO preventing that UI from receiving post processing effects.

 

Code (CSharp):

1. ....
2. private bool PointerInImage()
3.     {
4.         if (targetGraphic == null)
5.         {
6.             return false;
7.         }
8.  
9.         //get mouse pos
10.         Vector3 mv = Camera.main.ScreenToWorldPoint(MouseScreenPosition);
11.         //get world rect
12.         Rect worldRect = GetWorldRect(targetGraphic.rectTransform);
13.  
14.         //if mouse is in rect, find relative position in rect and compare to targetTexture
15.         if (worldRect.Contains(mv))
16.         {
17.             Texture2D tex = targetGraphic.mainTexture as Texture2D;
18.             float x = FindRelativePercentage(mv.x, worldRect.xMin, worldRect.xMax);
19.             float y = FindRelativePercentage(mv.y, worldRect.yMin, worldRect.yMax);
20.  
21.             //Multiply by texture dimensions to get position relative to texture
22.             x *= tex.width;
23.             y *= tex.height;
24.  
25.             //check if relative pos falls on non-transparent texture coord
26.             Color c = tex.GetPixel((int)x, (int)y);
27.             if (c.a > 0)
28.             {
29.                 //If so then our pointer is over the targetGraphic
30.                 return true;
31.             }
32.         }
33.         return false;
34.     }
35.    
36.     //Returns a value between 0 and 1 which is the percentage x is between a and b
37.     private float FindRelativePercentage(float x, float a, float b)
38.     {
39.         return (x - a) / (b - a);
40.     }
41.  
42.     //Returns a Rect relative to world coordinates. Very useful!
43.     private Rect GetWorldRect(RectTransform rectTransform)
44.     {
45.         Vector3[] corners = new Vector3[4];
46.         rectTransform.GetWorldCorners(corners);
47.         // Get the bottom left corner.
48.         Vector3 position = corners[0];
49.  
50.         Vector2 size = new Vector2(
51.             rectTransform.lossyScale.x * rectTransform.rect.size.x,
52.             rectTransform.lossyScale.y * rectTransform.rect.size.y);
53.  
54.         return new Rect(position, size);
55.     }
56.  

This function will tell you if the mouse is currently over a targetGraphic, which can be a texture2D, or texture from a button (in which case you'll need to cast it to tex2D) also make sure to enable read-write of the texture in texture import settings. I'm sure there's a way to get around that but that's for you to figure out. If you extend the button, you can call the EventSystem methods OnPointerDown, Up, Enter, Exit. You can also use

  EventSystem.current.IsPointerOverGameObject()

if you want the button to behave like a unity button raycasting-wise.Though it's a let response, hopefully, it can help anyone in the future!