>>373322694
I don't think that's the biggest challenge, but it is one of many. One technique I think would work is to have the tank prism windows write to the stencil buffer, then draw an opaque mesh around the tank with a stencil test not equal to the window stencil write. That way if you try to poke your head out the side you just see the opaque mesh, but looking through the windows are correctly transparent. Can do the same trick with a stencil-writing dome around open hatches. A player could still playspace move beyond the opaque mesh, but for that you can do a simpler bounds check and force the player back in their seat.