Render Texture on responsive UI

Hi everybody!

I have a problem that I'm not sure how to tackle.
I have an UI-based game and one mask features a Render Texture in form of a Raw Image (UI Element).
The content that is rendered gets stretched as I scale the UI around. As I googled, I can't change the size of a Render Texture at runtime (that would fix the issue). But I can create a new one every frame, which sounds not like a good Idea.
I tested the camera and rendered content in a separate scene, just rendering to screen. The issue only occurs when rendering to texture. In the end I just want the same behavior as rendering to screen normally, but taken my however stretched UI-Canvas as the virtual screen.

Maybe someone has an Idea?

 

I ended up writing a dirty script for now that checks the UI Elements RawImages Rect Transform for its resolution. If it changes, it creates a new RenderTexture with the corresponding resolution respecting a configurable base resolution and applies it to the RawImage component and a specified camera.

Here is the script if anyone needs it:

Code (CSharp):

1.  
2. using UnityEngine;
3. using UnityEngine.UI;
4.  
5. // Attach this script to your UI Element which has the RawImage component attached.
6. // Select a camera that should receive the updated texture, done.
7.  
8. [RequireComponent(typeof(RawImage))]
9. public class RenderTextureRescaler : MonoBehaviour
10. {
11.     public Camera cameraToUpdate;
12.     public int targetResolution = 512;
13.  
14.     private RenderTexture currentTexture;
15.     private RawImage rawImage;
16.     private RectTransform trans;
17.     private float aspect;
18.  
19.     private void Awake()
20.     {
21.         trans = (RectTransform)transform;
22.         rawImage = GetComponent<RawImage>();
23.  
24.         if (rawImage.texture)
25.             currentTexture = (RenderTexture)rawImage.texture;
26.         else
27.             currentTexture = CreateTexture();
28.  
29.         if (!cameraToUpdate)
30.         {
31.             Debug.LogError("You need to define a camera that receives the Render Texture!");
32.             Destroy(this);
33.         }
34.     }
35.  
36.     private void Update()
37.     {
38.         float currentAspect = trans.rect.width / trans.rect.height;
39.         if (currentAspect != aspect)
40.         {
41.             aspect = currentAspect;
42.             UpdateTexture();
43.         }
44.     }
45.  
46.     private void UpdateTexture()
47.     {
48.         currentTexture.Release();
49.         currentTexture = CreateTexture();
50.         rawImage.texture = currentTexture;
51.         cameraToUpdate.targetTexture = currentTexture;
52.     }
53.  
54.     private RenderTexture CreateTexture()
55.     {
56.         RenderTexture tex = new RenderTexture((int)(targetResolution * aspect), targetResolution, 24);
57.         tex.antiAliasing = 2;
58.         return tex;
59.     }
60. }
61.  

Usage: