PC 1.4 broke upwards firing traps...

DRKV

Wall of Flesh
In 1.3, if you placed a teal pressure plate right in-front of an upwards firing dart trap, the teal plate would get activated, then the projectile would be immediately destroyed. This let you create "gaps" in the game's projectile array, which made it possible to detect the creation of projectiles (a technique I refered to as "projectile interferometry"). This was possible, because upward firing dart traps spawned darts at just the right location, slightly below the edge of the dart trap tile. (More info here: PC - [Question] Weird Mechanics of Dart Traps and Teal Pressure Plates)

In 1.4 the positioning of these darts was "fixed". Upward firing traps now place darts 2 pixels higher, which makes all of this impossible, as far as I can tell.

EDIT: Alright, after some consideration, it seems like setting up an interferometer is still possible, it's just massively inconvenient, and very hard to do reliably...

1599935872640.png

(Left: 1.4, Right: 1.3)

Sorry about making a post with such little content, I was just sad and had to vent somewhere. :(
Consider this a replacement for the thread where I would have posted my cool sand/coin/nothing combo lock, that is completely broken now.

RIP
 
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I guess at least now it is consistent with sideways traps. Though i would prefer if those activated pads right next to them as well.
 
I was curious, if timing was a thing, relying on Teal Plates being either adjacent or exactly one tile away, why not just use Spear Traps instead? 🤔🍹

Sorry in advance if this is an obvious choice, but I tend to build my own machines with little-to-no outside influences. I don't see any situation where a Dart Trap is the better choice for a close, or near instant trigger if you plan on using Teal Plates. This isn't to excuse them not functioning properly, but considering that misfires are pretty common on servers, a Spear Trap will always be the better choice in my experience for instant triggers.
 
Sorry in advance if this is an obvious choice, but I tend to build my own machines with little-to-no outside influences. I don't see any situation where a Dart Trap is the better choice for a close, or near instant trigger if you plan on using Teal Plates. This isn't to excuse them not functioning properly, but considering that misfires are pretty common on servers, a Spear Trap will always be the better choice in my experience for instant triggers.
Maybe he wanted to use the longer cooldown the dart trap has? Also I'm fairly certain that a spear trap would send the signal twice.
 
Maybe he wanted to use the longer cooldown the dart trap has? Also I'm fairly certain that a spear trap would send the signal twice.
I was considering that, but I still don't see why you'd ever jeopardize the integrity of your trigger(s) for a time differential. 🤔🍹 That's why I'm assuming there's a part here I must be missing that makes the Dart Traps the obvious choice...?

If time differential is an issue, you could always use a pseudo-buffer or timed-trigger, especially now that we have 1/4 & 1/2 timers in 1.4.0. I haven't needed them for any of my builds thus far, but I haven't seen anyone complain about them being faulty yet. As long as your initial trigger doesn't fail, you can always create your own time differential, in my experience.
 
I was curious, if timing was a thing, relying on Teal Plates being either adjacent or exactly one tile away, why not just use Spear Traps instead? 🤔🍹

Sorry in advance if this is an obvious choice, but I tend to build my own machines with little-to-no outside influences. I don't see any situation where a Dart Trap is the better choice for a close, or near instant trigger if you plan on using Teal Plates. This isn't to excuse them not functioning properly, but considering that misfires are pretty common on servers, a Spear Trap will always be the better choice in my experience for instant triggers.
Well, spear trap don't work either when they are placed right against a teal pad.

What made upward firing traps so amazing, was precisely the fact that their timing was pretty much perfect. It took exactly one update for the dart to hit the teal pad, and then it was destroyed during the same update. Then you just have to wire up the output of the teal pad to a second dart trap, and you've created a gap in the projectile array.

It's still possible to make gaps, by firing two dart traps in parallel, and having the earlier one's dart hit a tile right in front of it. Actually, the biggest issue with the change, is that now you can't make projectiles that neatly tidy themselves up after triggering a real pad. This was pretty nice for making those projectile order detectors.

The teal pressure plate problem that I actually reported is not exclusive to traps. Pretty much any projectile, traveling at the right speed, can glitch past without being detected. It's just much easier to reproduce with dart traps.
 
Well, spear trap don't work either when they are placed right against a teal pad.
Yes, but I assumed you wanted the instant-trigger effect, I didn't think the spacing was the issue. I know that sometimes projectiles act weird whenever there's a possible desync in the game. Spear Traps don't seem to fail, ever, which most engines often do in multiplayer servers. I don't notice any memory spikes either, no matter how many Spear Traps are active, espcially if they're adjacent to the Teal Plate by exactly one tile between. 🤔🍹

What made upward firing traps so amazing, was precisely the fact that their timing was pretty much perfect. It took exactly one update for the dart to hit the teal pad, and then it was destroyed during the same update. Then you just have to wire up the output of the teal pad to a second dart trap, and you've created a gap in the projectile array.
Agh, I see what you mean! Yeah, as cool as that sounds, it's definitely an exploit & likely won't be returning. I'm not sure what unknown issues it might've caused when it existed, but I recommend using Spear Traps in it's place. If you do ever decide to try it, could you let me know if you notice a difference? [There'll need to be one tile gap between the Spear Trap & Teal Plate].

It's still possible to make gaps, by firing two dart traps in parallel, and having the earlier one's dart hit a tile right in front of it. Actually, the biggest issue with the change, is that now you can't make projectiles that neatly tidy themselves up after triggering a real pad. This was pretty nice for making those projectile order detectors.
So, I'm guessing the change hogs update memory now, that might cause misfires in an engine, like how actuated blocks might not activate, even if they are connected to the same wire color/ pulse. I don't seem to have that issue using Spear Traps, the amount of update memory projectiles hog up is the reason I started using them (i.e. falling Sand Blocks, etc).

The teal pressure plate problem that I actually reported is not exclusive to traps. Pretty much any projectile, traveling at the right speed, can glitch past without being detected. It's just much easier to reproduce with dart traps.
I don't think this is a new issue per se, as I've seen some dart projectiles hit imaginary walls on servers, I'm not sure if I've ever seen this happen with Teal Plates, but I have seen Dart Traps misfire, any time the game desyncs, many odd things can happen with engines (especially Sensors). I know you'll miss your previous set-up, but I'd still recommend Spear Traps, just based on their reliably/ consistency alone.
 
Yes, but I assumed you wanted the instant-trigger effect, I didn't think the spacing was the issue. I know that sometimes projectiles act weird whenever there's a possible desync in the game. Spear Traps don't seem to fail, ever, which most engines often do in multiplayer servers. I don't notice any memory spikes either, no matter how many Spear Traps are active, espcially if they're adjacent to the Teal Plate by exactly one tile between. 🤔🍹


Agh, I see what you mean! Yeah, as cool as that sounds, it's definitely an exploit & likely won't be returning. I'm not sure what unknown issues it might've caused when it existed, but I recommend using Spear Traps in it's place. If you do ever decide to try it, could you let me know if you notice a difference? [There'll need to be one tile gap between the Spear Trap & Teal Plate].


So, I'm guessing the change hogs update memory now, that might cause misfires in an engine, like how actuated blocks might not activate, even if they are connected to the same wire color/ pulse. I don't seem to have that issue using Spear Traps, the amount of update memory projectiles hog up is the reason I started using them (i.e. falling Sand Blocks, etc).


I don't think this is a new issue per se, as I've seen some dart projectiles hit imaginary walls on servers, I'm not sure if I've ever seen this happen with Teal Plates, but I have seen Dart Traps misfire, any time the game desyncs, many odd things can happen with engines (especially Sensors). I know you'll miss your previous set-up, but I'd still recommend Spear Traps, just based on their reliably/ consistency alone.
I'm not sure what you mean by "update memory", Terraria is pretty bad, but as far as I know, it doesn't have any sort of memory leak or high GC pressure problem with projectile updates. Multiplayer is a whole other can of worms. Terraria multiplayer is just buggy and unreliable in general, so for the sake of argument, all these problems apply mainly to single-player.

With my bug report, my main intention is to get teal pressure plates to work how they should. Right now, they activate when the hitbox of a projectile coincides with their hitbox after an update. Projectiles with high enough velocity can "teleport" past this hitbox between two updates. This is a classic problem when it comes to collision detection in games, and definitely not an intentional feature. There are also well know ways to solve it.

To reiterate, getting the "exploit" to work again is not my goal. (It would just be a side effect of the bug fix.)
 
@DRKV , Agh... I get it now. What I said is irrelevant, you're 100% correct, but I'll explain anyway.

Update: I refer to these & game tics interchangeably, at least when it refers to engines.
Update Memory: The number of individual items the game needs to account for in a single tic (sometimes causing visual or collision glitches).
Instant-Trigger: Any connected pulse or active parts that respond between one, one & one-half to two tics.
 
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