Bliting to framebuffer doesn't work?

Hi everyone,
i am new to image effects. I want to apply an image effect to my game in android. Therefore i can not use OnRenderImage() (see here). Instead i used this:

Code (CSharp):

1. [ExecuteInEditMode]
2. public class PostProcess : MonoBehaviour
3. {
4.     public Material blitMaterial;
5.  
6.     [SerializeField] Camera cam;
7.  
8.     RenderTexture myRenderTexture;
9.     void OnPreRender()
10.     {
11.         myRenderTexture = RenderTexture.GetTemporary(Screen.width, Screen.height, 16);
12.         cam.targetTexture = myRenderTexture;
13.     }
14.     void OnPostRender()
15.     {
16.         cam.targetTexture = null;
17.         Graphics.Blit(myRenderTexture, null as RenderTexture, blitMaterial);
18.         RenderTexture.ReleaseTemporary(myRenderTexture);
19.     }
20. }

The blitMaterial simply returns a green color for test purpose. However after applying everything nothing changes. The whole game still looks like it was before. The assigned camera in the inspector is correct. I also tried to blit it to a raw image and it worked but for the framebuffer it doesn't. So it looks like it has something to do with Graphics.Blit(). I also tried without HDR and MSAA.
I realy don't know what else might be the problem Therefore i want to ask you for help...

Thank you so much!

 

Ups, I didn't set my camera to Main.Camera. Therefore graphics.blit didn't blit to the view. Also i had to turn of MSAA. OnRenderImage() causes a black screen on some devices so i rather not use it. It was fixed with OnPreRender and OnPostRender.

For that android build I had to put the shader under Assets/Resources to make sure it is added to the build. I think i could also add the shader to "Project Settings -> Graphics -> Always include shader".

I attached the final Outline post effect (working on android). I used the command buffer explained similar to this blog...

I'm very glad it works now!