---------------------How to Parallax Ceilings and Walls----------------------
Joe Giddings
goldcard@intrstar.net

Everyone wonders how the space scenes were created in episode 2 of Duke.  This
is probably the easiest thing to do, and can be used to create all kinds of
interesting effects.  Refer to BIGSKY.MAP and SPACE.MAP to see my meaning.

First, draw out your room in 2d mode.  Any type of room will suffice.  For now
though, stick to a large rectangular room.

Second, use lines to draw a sector inside your room.  Use ALT-S to make the 
new sector valid.  Put the cursor on the lines and make them blocking, if you
like, but this is not necessary. You should now have a room like so :

                        ___________________________________
                        I _______________________________ I
                        I I                             I I
                        I I                             I I
                        I I                             I I
                        I I                             I I
                        I ------------------------------- I
                        I_________________________________I

Now, go into 3d mode and pick whatever texture you want for the OUTSIDE sector.
Don't use Big Orbit in this example.  Use the LA texture for simplicity.  Once it is in
place, press P to parallax the texture.  Then, move the pointer to the ceiling
of the outer sector and hold down the left mouse button.  Press PgDn, until
the ceiling in this part touches to floor.  Now place the same texture on the
ceiling and parallax it.  All you should have now is a floor and a cityscape.
The city will look weird, but when you play the level it will look normal.

Space scenes are a little different.  Big Orbit has an annoying tendency to
kill you.  Do the same for space, but then make a sector inside the inner
sector and make it something else, like a room.  Make sure the walls block so
no one can wander out into space and die.  This time, parallax the floors as
well.

IMPORTANT!!!! :
        The only ceiling you have to pull down is the outermost sector.  This
        is because if you pull down the other sectors as well, you cannot 
        place sprites in space.  See SPACE.MAP for example.

Once finished, you can use standard wall masking to put in glass or force
fields.

Using this method, one could surround an entire level and make it look like
the level is in space, using windows and such.

Have fun!