The easiest way to make a window is to take an existing .fps file and change it to fit your needs. First thing to do is line everything up in whatever modeling program you use. For example if you want to have a round/circle window, import the .x models that is similar to your new window model and make sure that the glass, frame and csg are in line with the old models. When I say in line, I mean that the model's origin is in the same place. If everything is good then export your new window models and change the .fps file. Also the new glass needs to be an entity so you will need to make a .fpe file or use the entity maker in the tools section.
;Segment Spec
;Header
partmax = 2
lastmeshmax = 0
;Segment Parts
partmode0 = 0
meshname0 = meshbank\scifi\scenery\windows\win_c\win_c_frame.x <---- change this to your new frame
offx0 = 0
offy0 = -5
offz0 = 50
rotx0 = 0
roty0 = 0
rotz0 = 0
texture0 = texturebank\scifi\scenery\windows\win_c\win_c_d2.tga
transparency0 = 0
effect0 = effectbank\bump\bump.fx
colmode0 = 3
csgmesh0 =
csgmode0 = 0
csgimmune0 = 1
lightmode0 = 0
multimeshmode0 = 0
materialindex0 = 3
partmode1 = 3
meshname1 = entitybank\scifi\scenery\glass\circleview.fpe <---- change this to your new fpe
offx1 = 0
offy1 = -5
offz1 = 50
rotx1 = 0
roty1 = 0
rotz1 = 0
texture1 =
transparency1 = 0
effect1 =
colmode1 = 0
csgmesh1 =
csgmode1 = 0
csgimmune1 = 0
lightmode1 = 0
multimeshmode1 = 0
materialindex1 = 3
partmode2 = 1
meshname2 = meshbank\scifi\scenery\windows\win_c\win_c_punch.x <---- change this to your new csg
offx2 = 0
offy2 = -5
offz2 = 50
rotx2 = 0
roty2 = 0
rotz2 = 0
texture2 = texturebank\common\basepunch.tga
transparency2 = 0
effect2 =
colmode2 = 0
csgmesh2 =
csgmode2 = 0
csgimmune2 = 0
lightmode2 = 0
multimeshmode2 = 0
materialindex2 = 3
;Segment Visibility
visoverlay = 1
visfloor = -1
visroof = -1
viswallb = -1
viswallr = -1
viswallf = -1
viswalll = -1
viscornertl = -1
viscornertr = -1
viscornerbr = -1
viscornerbl = -1
;Segment Blueprint
mode = 0
symbol = 0
floorsizey = 0
sidesizex = 0
sidesizey = 0
sidesizez = 0
groundmode = 0
kindof = 0
;end
You can do this with almost any gameobject in fpsc, including weapons. It's how we use to do it before entity workshop and others made it easier. Also one last thing, in your C:\\The Game Creators\FPS Creator\Docs folder, you will find a pdf file that says ocfpsguide. Starting on page 230, is a tutorial by Gamer X about how to make a window segment.
Enjoy!