Jatopian
Level: Smitemaster
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Registered: 07-31-2005
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File: Jatopians Inferno.hold (38.9 KB)
Downloaded 50 times.
License: Public Domain

I have here a hold, which has a demo embedded. The hold entrance has stairs near it; go down them to get to the room in which the bug is demonstrated. Or you could just watch the demo.

____________________________
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[Last edited by Jatopian at 07-06-2007 02:25 AM : description]

Jatopian
Level: Smitemaster
Rank Points: 1842
Registered: 07-31-2005
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Hey mrimer, I think I've figured out what causes this behavior. Apparently, while stepping onto a pressure plate is processed at the beginning of the turn (before briar growth), stepping off an on/off pressure plate is not processed until the end of the turn. So the briar appears to grow while unconnected because it grows out and then is cut off when the door goes back up. So the bug(?) lies in pressure plate processing & not briars.

To show it, here's a little setup to illustrate the behavior:

..._..
.._...
.P.WWW
...D=-
...WWW

Where P is the player, D is a closed yellow door, and the underscores are two on/off pressure plates both set to toggle D, and the blue is a west-facing rattler. Now, if the player moves onto the southwest plate, then moves in one turn onto the northeast pressure plate, this should (as is intuitive to me) toggle the door twice in the same turn and thus not let the rattler out. However, because the on event is processed, then the rattler movement, then the off event, the rattler escapes.

____________________________
DROD has some really great music.
Make your pressure plates 3.0 style!
DROD architecture idea generator

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[Last edited by Jatopian at 06-20-2007 06:24 PM]

coppro
Level: Smitemaster
Rank Points: 1308
Registered: 11-24-2005
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Aaah! Run away! A gold dragon guarding a river!

Maybe I should cut back on the roguelikes.

schep
Level: Smitemaster

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No, that's intentional. The idea is that if something leaves a pressure plate and something else steps on during the same turn, the plate never fires. Besides, I'm pretty sure the briars in that room were messed up even during turns when doors aren't moving.

TFMurphy
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No, what Jatopian said is exactly why the briars were acting the way they did.

This leads to some pretty... well... interesting effects. You can code a loop for a 2-tile Serpent to traverse that has On-Off Pressure Plates every two tiles, all controlling the same door.

If the door starts closed, then *EVERYTHING* that moves after the Serpent will pass through the door as if it's open, and only have the door closed on them at the end of the turn. Beethro, however, will find it impassable.

If the door starts open, then everything that moves after the Serpent will find it closed every other turn and Beethro will never find it impassable.

The basic behavior is intentional, yes (so that on-off plates don't trigger off until we're sure nothing else has moved on them), but the way it works with multiple pressure plates is a little unintuitive. Those briar roots were working fine.

Tahnan
Level: Smitemaster

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File: Frozen Roach.hold (994 bytes)
Downloaded 47 times.
License: Public Domain

TFMurphy wrote:
This leads to some pretty... well... interesting effects. You can code a loop for a 2-tile Serpent to traverse that has On-Off Pressure Plates every two tiles, all controlling the same door.

Not one serpent, since it'll have to spend half its turns holding down a single door. But the attached hold shows what I think TF had in mind, and it is pretty seriously weird. Not a bug, but not at all the kind of thing I'd expect to happen.

TFMurphy
Level: Smitemaster
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True: with one serpent, it'd be every other turn that the condition applied, which I caught for the second example (door open to later monsters, door closed to Beethro) but not for the first. With two serpents, the trick is complete: if the door starts open, you have something that's impassable to later monsters but open for earlier ones (and Beethro). And if it starts closed, you have something that is impassable to earlier monsters (and Beethro) but open for later ones.

Anyways, as interesting a mechanic as it is, we're not really supposed to do puzzles that rely on monster movement order, and other than delaying *all* pressure plates to be resolved at the end of the turn, I can't think of an easy way to resolve this. And I don't really want to figure out how much that change would break existing uses (or whether it's a good idea in the first place).

But it's still fun to play with.

Tahnan
Level: Smitemaster

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TFMurphy wrote:
... we're not really supposed to do puzzles that rely on monster movement order...

We're not? Uhoh.

Actually, I think puzzles that rely on monster movement order, when that fact is made clear, is fine. Witness the variety of LarryMurk holds with scrolls that note "roach moves before serpents" or "goblin moves last" or the like. Admittedly, I recall being particularly annoyed at an impossible-seeming narrow corridor with rock golems, until I learned that even though it looked symmetric, movement order made it such that it could be solved if you were doing exactly what I was doing, only along the right-hand wall instead of the left-hand wall. (At least now, movement order is no longer hidden from the player.)

jbluestein
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TFMurphy wrote:
Anyways, as interesting a mechanic as it is, we're not really supposed to do puzzles that rely on monster movement order, and other than delaying *all* pressure plates to be resolved at the end of the turn, I can't think of an easy way to resolve this. And I don't really want to figure out how much that change would break existing uses (or whether it's a good idea in the first place).

There are a lot of puzzles that depend on monster movement order, and the number is growing. More to the point, this was more of an issue before 3.0, since you can now determine movement order just by right-clicking on the monsters.

Josh

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TFMurphy
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Well, true, there *are* some nice tricks based on a movement order that can be done and can still be puzzle-oriented. On the other hand though, I'm not sure this trick with pressure plates is as fair.

Though I have no doubt that if left this way, we'll see some interesting uses of it regardless. Though you could say that about any unintended result, no matter how fair or not it is.

EDIT: After thinking about it, we can probably explain it away as being slow-release pressure plates: it takes more time for them to pop up than it does for something to slam it down. Feels more logical when you think of it that way, but it'll still lead to surprises, like any movement order does. Not that that's a bad thing.

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[Last edited by TFMurphy at 06-21-2007 06:48 PM]

mrimer
Level: Legendary Smitemaster

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Thanks for the analysis and discussion from everyone. So, if I understand correctly, the consensus is that this behavior is an artifact of the game logic, and not a bug. Based on what I read here, I agree.

____________________________
Gandalf? Yes... That's what they used to call me.
Gandalf the Grey. That was my name.
I am Gandalf the White.
And I come back to you now at the turn of the tide.

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[Last edited by mrimer at 06-21-2007 07:16 PM]

Skylancer64
Level: Delver
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File: Safety Zones.hold (2.1 KB)
Downloaded 41 times.
License: Public Domain

Interestingly enough, this behavior in effect implements one of the feature requests that was brought up a while ago. Using this trick, we can now create Beethro-only areas, and Beethro-excluded areas. Not only that, but critter access to these areas can be implemented conditionally as mentioned earlier by tweaking the movement order. With careful movement ordering in the editor, this trick allows anything from goblin-only areas to non-serpent areas, With the small annoyance of continually flashing orb lightning, of course. And the minor problem of newly spawned critters always being placed last in the movement list.

Even so, as long as players are made aware that these doors are working this way, this could actually become a useful puzzle element in itself.

Demonstration attached.

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Jatopian
Level: Smitemaster
Rank Points: 1842
Registered: 07-31-2005
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Quite so, Skylancer64. Although a crude version of this was possible in JtRH using a mimic & character, and indeed was well-explored by one Niccus (now inactive) this does refine the capability immensely. Hopefully we shan't see the massive abuse potentials materialize since the means are so obscure.

____________________________
DROD has some really great music.
Make your pressure plates 3.0 style!
DROD architecture idea generator