
While fiddling /w deu y'day, i found 2 new features that I've never seen in any
wad from you guys or from id.

first, i found one can create a sortof solid crystal box,
and u can walk on top of it w/o any the famous hall of mirror effect.
secondly, you can have walls that u can see thru, but not
shoot thru. (behaves exactly as regular walls, it block sounds too!!)

here's how to create  the "x'tal" box:
to create such a sector, you need at least 2 sectors, one being inside the other
with the floor height u want it to be, and the enclosing sector must have
a floor height the same with its surrounding sectors.
make all the linedefs two sided.(inner and outter sectors) 
make all of the linedefs reference from inner sector point to itself.
make the linedefs ref of outter sector point to its surrounding sector.
that's it. The good news is that NO HALL OF MIRROR effect generated!

creating the seethru/noshoot walls, has a similar manner. 2 sectors required.
all other things are the same as above. except that outter sector
must only have one linedefs reference(one sided) and pointing out.

if you you're a bone head :), i have included a sample wad of these
two feature.

a couple of interesting thing to see from this wad are, one is that
the x'tal box can be shot thru, except for  Rockets and Plasma gun.
but u can put wall on their edges with seethru/noshoot walls, thus perfect.
secondly, u can squeeze in the linedef that is shared by the last stair and
the x'tal box. very weird.

i also tried combo of xtal box & lift, it will have a HOM if your view
is higher than the lift. other combinations of features are left to
you, wad designer. :)

i would imagine that from this findings one can create a "crystal palace".....
u can see thru all things, but nasty traps are waiting.... huaaahaaaa...:)

comments/suggestions are welcome!

===Martin (leo@cae.wisc.edu)
