Change color in the overlap of two 3D objects

I'm doing an x-ray shader, I got this code, but for what I want it's incomplete. Here's the shader website:
http://www.photonworkshop.com/index.php/blog/x-ray-shader/

My knowledge in shader is pretty basic, I'm studying weeks in Unity documentation and in various tutorials, but nothing comes close to what I need.

I need to make if one object is on top of the other the color turns green, in addition to having a density control of the material that makes it darker or lighter, and the same with the color intersected.
And to finish the possibility of putting a texture in black and white and have an individual control the internal with these same characteristics. If you can help me, thank you.
I tried via C # to change the color, but there remained a wagon hehehehhehehe.
This is what I have.

This is what I want to do.



I tried to use overlay, but it did not work. I needed to know how to get pixel rendering from the scene and compare with conditionals, or if someone has a better idea, merge or anything else will be welcome. Thank you.

 

Detail, my intention is to be able to rotate the objects and have more details of them when they are hidden behind objects with great density.

 

What you are looking for is probably a shader with additive blending.