Bug UI Camera overriding shader effects

EDIT: Solved it by using Graphics.Blit with OnRenderImage... For some reason I thought Graphics.Blit was deprecated but it looks like I was wrong. Still don't understand why the following code doesn't work and would appreciate insight


I have two cameras, "vrCamera" and "UI_Camera"

I'm using a CommandBuffer.Blit() with the vrCamera to apply shaders. It works fine:


As soon as I turn on UI_Camera, it undoes the shader:


The UI_Camera is not overriding the vr_camera, I know this because the UI_Camera is pointed at 0,0,0 and the horizon would be in the center of the screen. It's still displaying the vrCamera view, just without the shader.

The only work around I've been able to find is to render the vrCamera to a render texture and then display that as a raw image on the UI. This is problematic as it removes the stereoscopic rendering.

Has anyone else dealt with this? The following is my code to activate shaders:

Code (CSharp):

1.  public void ActivateShaders(List<int> activePositions)
2.         {
3.             if (commandBuffer != null)
4.             {
5.                 commandBuffer.ReleaseTemporaryRT(tempRT);
6.                 Camera.main.RemoveCommandBuffer(CameraEvent.AfterEverything, commandBuffer);
7.             }
8.  
9.             Debug.Log("Activate shaders by position: " + activePositions.ToArray().ToCommaSeparatedString());
10.             this.activePositions = activePositions;
11.             activeNames.Clear();
12.             currentActiveNames.Clear();
13.             currentActivePositions.Clear();
14.          
15.             // Create a new command buffer
16.             commandBuffer = new CommandBuffer();
17.  
18.                 // Create a temporary render texture to hold the intermediate results
19.                 tempRT = Shader.PropertyToID("_TempRT");
20.                 commandBuffer.GetTemporaryRT(tempRT, Screen.width, Screen.height, 0, FilterMode.Bilinear);
21.  
22.                 // Copy the source render target to the temporary render texture
23.                 commandBuffer.Blit(BuiltinRenderTextureType.CurrentActive, tempRT);
24.  
25.                 // Apply each shader in turn
26.                     foreach (int currShader in activePositions)
27.                     {
28.                         currentActivePositions.Add(currShader);
29.                         activeNames.Add(shaderMaterials[currShader].name);
30.                         currentActiveNames.Add(shaderMaterials[currShader].name);
31.                         Material shaderMaterial = shaderMaterials[currShader];
32.                         // Set the shader material properties here if necessary
33.  
34.                         // Apply the shader
35.                         commandBuffer.Blit(tempRT, BuiltinRenderTextureType.CurrentActive, shaderMaterial);
36.          
37.                         // Copy the result back to the temporary render texture for the next shader
38.                         commandBuffer.Blit(BuiltinRenderTextureType.CurrentActive, tempRT);
39.                     }
40.  
41.                 // Copy the final result back to the source render target
42.                 commandBuffer.Blit(tempRT, BuiltinRenderTextureType.CurrentActive);
43.              
44.                 // Add the command buffer to the camera
45.                 sxrSettings.Instance.vrCamera.AddCommandBuffer(CameraEvent.AfterEverything, commandBuffer);
46.             }

I am 100% certain it's the UI_Camera (and specifically its camera component) as turning it off/on is the only thing that causes the shader to stop working