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#514 TNT, Level 30, Can't get the red key
In TNT, Level 30, after killing the Cyberdemon, you
push the button on the wall and stairs will rise in the
middle of the room so you can use them to reach the red
key at the top, but the stairs stop rising and you just
can't access it.
Have to use the idkfa cheat at this point to continue
playing.
Logged In: NO
You can use the noclip cheat to jump on top of the wall.
Anyway, I've never experienced this bug. (probably because I haven't played TNT yet!)
Seems like the stairbuilder occasionally creates stairs that are too low.
also experienced this.
fell off of the 'maze' at the very beginning of the level, used noclip to get up the other side: dunno if the last teleporter of the maze is also a trigger to lower the red-key platform so as to confuse cheaters?
Either way: played rest of level normally, killed cyberdaemon, flipped switch, climbed pillar, cannot reach red key... using prboom v2.5.0, and tnt.wad with TNT31.WAD (fixes missing key in level 31 (pharaoh)).
TNT MAP30 depends upon buggy behavior of the Doom2 engine.
Faulty logic causes it to increment the height of some stair steps twice. The MAP30 developer just took some line segments out to compensate.
This is a bug that plagues Boom ports, because Boom fixed the buggy stair builder. Now every port has to put in a switch to restore the original buggy behavior for TNT MAP30.
I tried prboom and Edge, and both build the stairs to the same height as
DoomLegacy. There was a stairbuilder bug that caused some steps to be
double height. It was fixed in Boom, and DoomLegacy uses the same code.
TNT MAP30 depends upon the bug to get those stairs at the right height.
Looking at the wad with an editor there were originally 24 steps. Some
linedefs were removed to make it 18 steps in the stair raiser.
Only 8 are visible in the room,
the others are there make the visible steps 16 high.
According to the Unofficial Doom Spec, each step raises by 8.
This makes the last step at -128 + ( 18 * 8 ) = 16.
The top of the pillar is 64, so by design it is 48 short of the top.
Playing Doom95, the steps go even with the pillar top, behaving as if
there were 24 steps.
The patch w76_TNT_MAP30_stairs.patch, detects TNT and causes the
stair builder to use the old buggy code.
*** w76_TNT_MAP30_stair
patchfile = w76_TNT_MAP30_stair.patch
- committed revision 852 by wesley johnson
TNT MAP30 depends upon a stair builder bug that was fixed by Boom.
Fix using DemoAdapt so that for TNT MAP30, it disables the Boom
stairbuilder fix (giving the original buggy code). Sometimes the bug
increments a stair twice. TNT MAP30 has 24 steps, but they removed some
linedefs to have only 18 steps (some of which increment by 16) because
of the bug.
Close. Fixed SVN852.