How to check if a part is overlapping another part?

So at a certain camera angle, I want to make LocalScript to check if a blue part is overlapping a red part then the blue part would become transparent.

But if the blue part is now longer overlapping the red part when you turn the camera to another angle then the blue part would return to normal

I think this involves mostly in ray casting...

I'm not sure why it's doing that? It may be the transparency of the base-plate or other things behind the parts but other than that I cannot help very well.