Revealing a background under another in a 360 space

Hello everyone,

i’m pretty new to three js and i’m making some experiment.
What i’m trying to do now is to have two 360 background overlapping in a way that i only see one of them, and moving the camera around pointing always at a plane object i would like to see the second background through that object. Like a sort of magical magnifying glass.

I’ve started from this example three.js examples and now i’m stuck at this point
First of all the one that should be the always visible background is always hidden by the second. And second the second background should only visible inside the place a not viceversa.

If someons could help it will bu much appreciated.

nevermind, i think i did