CSG in shaders

Hi,

I'm looking for a way to mimic CSG behaviour - cut off part of a mesh by other (invisible) mesh.
My first attempt was to use stencil buffer, but...
- I use deferred rendering, so no stencil here.
- I cannot use command buffers (both meshes are already on the scene, as a plain gameobjects) - so my approach must be 100% shader based
- Both meshes are a part of larger rendering pipeline, so I cannot e.g. add another camera or fiddle with render textures.

Is it possible to achieve something like this purely in shaders?

 

Nope.