I have never seen this done and only found a little information searching the forum. I know for some of you that’s been using FPSC for a while, this is child’s play. However I share this for those who may be having difficulties with sky lights. What I did was copy the entity and meshbank folders for the sci-fi large window to my own. Then I opened the models and flipped them on there side and lowered them to the ground. Then using FPSCREATOR-SEGEDKIT, created the segment file. I had to tweak the offy and offz to get the entity lined up just right and then added the materialindex. You will need to edit the segments fps file for the room you will be using this in. Change the csgimmune?= 1 to csgimmune?= 0 for the floor part.
Download Attached.
Enjoy.