I do not see a use currently. I would like to suggest Tmp of 1 2 3 4 5 6 7 8 make the glas one way reflective for one of those directions. Photon can pass through from any side except the one indicated. its about the side of the glas not the attack angle of the photons. Hot photons would be fully reflected on that side and not pass heat to the GLAS. imagine an octagonal piece of GLAS tmp 1 would be the north most side with 2 being clockwise from 1. that side would be reflective of phot hitting it from OUTSIDE the block of GLAS. so regardless of the shape if you have a 45 degree or 90 degree line it can be selected as 1 of those values. you could have a square shape with one corner cut at 45 degrees and select the tmp that would corespond on the imaginary octagon. I know, my head is swimming a bit to.
That would be pretty awesome!