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peach freak

Monster teleport trap issue (won't teleport if shot first)

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In one of my maps, I have a Cyberdemon. It's "sleeping" when you first encounter it (like the Cyberdemons in Cyberden). It's surrounded by a one-unit high sector so that it can't see you while you can see it (like Cyberden). There is a switch next to it that lowers the barrier. The Cyberdemon then sees you, walks forward, and teleports away.

However, if you move off to the side and shoot it where it can't see you, it will awaken and start moving around, but never teleport. Even if you stand directly in front of it so that it should walk towards you, it'll keep bouncing around.

Here is an image of the area:



The Cyberdemon is enclosed in that square sector. The two outer octagonal sectors have their floor heights one unit below the ceiling (the outer one is there so that when that sector lowers, it reveals a different texture on the single sided lines behind it). I used to have the teleport lines on all four lines surrounding the Cyberdemon, but moved it up front as an experiment, where the same issue happens.

How come the Cyberdemon can't teleport if shot before it sees and starts moving around? If shot first and you watch it on the automap, it never crosses that line as if it's marked as Block Monster or something (which it isn't). The line (and former four lines) are all WR, not W1, in case something like that would happen. Is there not enough space for it to move around if something like this happens? Do I need to make that entire closure a tad bigger to accommodate Mr. Cyberdemon?

Thanks.

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peach freak said:

Is there not enough space for it to move around if something like this happens?

Yes. The doorway seems to be exactly as wide as he is. Once he gets pushed even by a fraction of a single map unit sideways, he will not be able to fit through the door. In the Doom engine, monster's capabilities of correcting their movement to fit small gaps aren't any good.

peach freak said:

Do I need to make that entire closure a tad bigger to accommodate Mr. Cyberdemon?

Either that, or you can prevent him from being pushed sideways by making the inner square's eastern and western linedefs monster-blocking.

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Also remember that monsters do not activate lines on their outer edge. It's about 1/4-to-1/3 in the monster from its outer edge. Same goes for players. Thus when the cyberdemon moves around in that diamond-shape, Though his outer edge might cross the line, he will still not teleport until he crosses it a bit further.

On that note, an easy fix to your problem would be to simply move the teleporting line closer to the center of the cyberdemon so the little up/down movement he is able to get allows him to "cross" the line.

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Fonze said:

Also remember that monsters do not activate lines on their outer edge. It's about 1/4-to-1/3 in the monster from its outer edge.

It's exactly 1/2. Objects activate lines with their centers. Bounding boxes don't mean anything at all.

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Interesting; always seemed to me lines couldn't be placed near the exact center of a monster and still be activated, like at least a few pixels of berth is needed for the monster to pass through it.

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Maybe it's some variation of the line skipping bug. I have a very basic idea of how this works.

I typically make the squares of teleporting lines pretty small, but not exactly 2x2. More like 8x8.

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For a walkover special linedef to be triggered, the activator thing's center needs to be on one side of the linedef in one tic (one position) and on the other side of the linedef in the next tic (next position), AND the thing's collision box must overlap the linedef in the latter tic. That's all into it. (Well, one more thing into it is that many types of walkover actions can only be triggered by players and never by monsters, but that's generally known.)

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Cool; thanks for the info scifista. Always nice to learn about some of the finer points.

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Thanks for the info. I created a 16x16 mini-sector over the center of the Cyberdemon and that appears to have worked. I'll try out some other things if there's a better way.

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