How to go about making a system to clip geometry when intersecting with another?

[giantSwing]

Hi everyone, in my game I wanted to do some fake really simple lighting so I have a sphere with a simple shader, it looks something like this:

It does the job and I actually kinda like how it looks, the problem is that the sphere (obviously) can go through the walls, kinda destroying the illusion, so I would like to know if there is a simple way to “clip” the lighting sphere so that it doesnt go through the wall

Thank you for your time and sorry for my english

[giantSwing]

Im also thinking that because the background will always be black I could somehow grab the screen color (before the light is rendered) and if the pixel is black or near black, dont render the light, but I dont know how to go about doing that either to be honest…