special effects 'global' shader

I would like to render my whole scene using a custom shader for special effect, but without modifying the existing objects materials. For example bend all the objects with a geometry shader, and also change the way the objects are displayed with a pixel shader (I will need access to the object’s texture, depth information). Is there any way I can do this using Unity?

I saw many questions like this asked, but no answers…?

I asked the same question on the forums, and got something working. It uses replacement shaders, which will get access to all the material properties at render time.

https://forum.unity.com/threads/apply-shader-to-all-objects-in-the-scene.563350/

I followed this excellent replacement shaders tutorial: