A LID is a location, usually 1 px², that permanently marks a unit. This takes advantage of collision boxes to help identify and track non-unique units.



The unit's collision box prevents other units from ever entering the LID location, permanently tagging the unit. If the unit becomes stacked with other similar units, the LID may become unattached. Units that can ignore collision boxes in specific circumstances, such as Zerg units that burrow and workers, are restricted by this limitation.

Although the use of locations greater in size than 1 px² can be used, it is not suggested. Larger locations risk becoming unattached from the tagged unit. Because triggers run at 11.9 Hz, faster units with smaller collision frames such as Zerglings can become unattached from their LID. Below is a list of units that work with a 1 px² location.











* These units can become stacked in normal gameplay.

There are units included on this list that partially work. For example, a ghost's LID will remain attached if he moves vertically, but any horizontal movement will detach the location.


Use of Inverted LIDs

An inverted LID (xLID) does not carry any advantages over traditional LIDs; in fact, they are slightly disadvantageous. Because a xLID requires that a unit to remain outside of the location at all times, a unit may be able to escape a xLID that cannot escape a LID. If the xLID and LID were put on the very edge of a unit's collision frame, the unit would be in the LID, but not in the xLID.


Examples

I am attaching two proof-of-concept maps. LID Test was made by me. You can place any unit in the center of the dark square and test it. The triggers will work with anything; though, there are still the restrictions above.

Civilian Tracker is Azrael's proof-of-concept. The damaged civilian will roam around with junk yard dog AI among other civilians for five minutes. At the end the unit within the LID will be removed. It should be the damaged civilian.


Hopefully this will help you all in creating maps

Attachments:

Post has been edited 5 time(s), last time on Apr 18 2012, 5:50 am by Sacrieur.

This is something that didn't used to work and I'm glad it does now. That exact map, Civilian Tracker, used to fail at tracking the right civilian 100% of the time, and now it works 100% of the time. I am grateful you made me try it again

Major props and some karma for an excellent posting, and for going to the trouble of figuring out which units work and which don't.

Post has been edited 3 time(s), last time on Aug 14 2012, 3:44 am by Azrael.

I don't really see how this is anything new, other than being a nice list of units all together in one place.

Also, it is possible to get regular units to temporarily stack over each other, such as when you have several units in a confined place and you somehow add an extra one, causing all units to jostle around trying to find new stable positions - zerg egg morphing, or SCV repairing being easy ways to get this to happen. I once had a group of 2 tanks and 3 goliaths running around each other for a solid 3 minutes when I sent an SCV in to repair them, in the end I had to manually order them all to stop and stand in specific spots to stop them.

Isn't really new, but it is a concept that wasn't documented, or even well studied.

And yes, I did mention overlap glitching as something that could ruin the effect.

Post has been edited 1 time(s), last time on Jun 14 2010, 6:49 am by Sacrieur.

Well, it certainly didn't work at the time Brood War was released. Not sure what changed between then and now.

Post has been edited 2 time(s), last time on Oct 12 2010, 12:13 pm by DevliN. Reason: Mineral abuse.

Hyper Trigs? I dunno how long they have been used.

Hyper triggers wouldn't have been known about, and you need 1x1 pixel locations to do this properly, and the smallest location Staredit will let you make is 32x32 (1 tile).

It sucks it doesn't work on Infested Terran though, I love those little buggers

Post has been edited 5 time(s), last time on Aug 14 2012, 3:45 am by Azrael.

This has been documented before. It's just that you guys probably weren't around at the time. I clearly remember there being some thread I took part in, where lists of units that could/couldn't escape a 1x1 location were posted. Falkoner was also somehow involved. I don't know whether that thread was made before SEN went down or not, but finding that topic is worth a try.

Yeah it definitely was. Ideas implementing this have already been thought up, and back in the day when I actually had spare time I planned to create a nice vHP concept map with it. Too late now.

This is all old news and many a map have used it. Although, I'm sure a new list of units able escape a 1x1 location would be nice. Those are the units that are able to move more than the distance from where the location centers to their collision box in any direction within two game frames (triggers fire every 2 frames, right? Hence dcs lasting 1/12 a second and the framerate of 24?). Zerglings with speed and zealots with speed are able to escape.

I was inactive here for a few years before 2009, so that's a possibility.

Regardless, "being documented before" isn't helpful when said documentation no longer exists.

Post has been edited 5 time(s), last time on Dec 12 2014, 8:21 pm by Azrael.

im new to map making, so im not sure about this, but if i have 2 triggers both say: condition: always action: center location on X unit. if i have 2 units, will 1 trigger set to each unit?

They will both center on the same unit, unless you placed the 1x1 locations accordlingly and are moving the locations to themselves. Two locations being moved to the same type of unit in a large location covering both of them will both bind to the same one.

so the locations need to already be set where each unit is?

Yes. Also don't forget the preserve trigger actions.

Can't you use slightly inverted locations to better effect? Or do they escape those too?


I did some stuff with these ages ago. Kinda stupid that I never recorded anything.

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Yes, I'm reviving this thread to answer this question. I still need to test heroes anyway >_>.
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Inverted locations have no effect. Since locations are 1x1 pixel and pixels are the most minimal of detection, a 1x1 location is all-or-nothing sort of thing. Either the location is completely on a unit, or the unit is not in the location at all. Units do not move half-way into a pixel =P

I forget; does this work with infested kerris or not?

Nope (vertical works, horizontal does not). Curiously enough, Kerri's hitbox and movement speed is the exact same as a ghost.

Meh. Not sure what to use as zombies in my map now. Maybe drones, but that's meh.

Have you tested with unit slowing? I would assume that a while lot more units become viable when slowed down.