koobas.hobune.stream
How to render World Space UI on top of 3d content?
I believe this problem exist for years. I can find some "primitive" solutions: custom ui shader, extra camera for ui layer.
These two solutions don't work in advanced situation like HDRP or VR. the second camera doesn't work as expected and the post-process will mess up ui (especially when you have DoF).
So, is there any good way to render World Space UI on top of 3d content?
Second camera works good for me, especially because Antialiasing image effect makes Text unreadable on low resolutions. Then I applied DoF on main camera and works pretty well, but your case might be different. 
If you need a particular image effect to apply on it, why don't you just use a RenderTexture? You capture the UI without any post-process applied to the camera (otherwise you won't be able to have transparent background), then you just need a normal shader that writes on top of 3D objects (like this) or an additional camera.
