This article has been approved and can also be read at the University. - Leif Ericson

Tutorial download link
The Hero's Inventory download

Finally after discovering this by accident, 5 years ago, I am releasing a tutorial on how to make units have negative IDs and the tricks that come along with this. I have used this trick in a couple of my maps, such as The Heatlh Potion Trick. But what is the double negative effect? It's when you give units/buildings negative unit IDs, whether by themselves or paired up with another unit to achieve new AoK tricks. I would not suggest new map makers try this because it is confusing, sometimes irritating, and you need to have a couple programs installed. First off you need to have Trigger Studio and GeniED installed on your computer. I suggest you also install Aokts with s_t_c's addon because it's really useful anyways. Now here are the steps to make negative ID unit pairs(with pictures too!)

Step 1: Run GeniED and unhide all units from editor.
example

Step 2: Go ingame and drop a projectile down. (i always use an arrow)
example

Step 3: Load up AoKTS and look at the arrow you placed.
example

Step 4: Change the arrow to an archer (any non projectile works)
example

Step 5: Drop 2+ more arrows ingame and return to AoKTS. You will now have a set of units with the same negative ID. Delete the remainder.
example


Now you are ready to start making some new tricks. Change the units around to however you see fit. Most of these tricks need to have a pair of units with the same negative ID except trick #3 in the tutorial. The easiest thing you can achieve is garrison both of these units into a normal unit and you can unload them indefinitely. As far as I understand, when two units have the same negative ID, they are basically the same unit now. However one of the units acts as a dominate unit and the other is recessive. Example, if you garrisoned both the negative ID units into a normal unit and try to ungarrison them, one will remain garrisoned in the unit and have its icon, and the other will be unloaded. So sometimes you may have to switch the units to get the icon or effect you want. Note that you can use buildings for icons but they get the icons of units sometimes for whatever reason. Read the scenario instructions in the map to achieve each specific trick. I have not done a lot of testing on this double negative effect in the editor, almost no testing in multiplayer, and zero testing with campaigns. This is where I need your help.

There are a lot of oddities that happen with negative ID units. The first is that you cannot select them, unless you own the object and then it is only selectable with the comma "," or period button "." Another is the stupid "unable to unload" error that happens for whatever reason. An example of this is at the end of the tutorial. Also when a trigger with a remove object effect goes off, it sometimes gives the same "unable to unload" message to things that would normally work. In addition, negative ID gaia units DO NOT convert to the player's control when a unit is in range. Good for making a town or other graphical use in a map with 8 human players. Play around with this system (negative ID unit pairs) and find out for yourself what happens and what is possible!

Credits to Scenario_t_c for helping me 5 years ago and Hawk_KK for this post because after I discovered the double negative effect years ago, I didn't know how to do it again (make units have negative ids) until i read this, hence why I didn't release this until now.

Good luck! Post any questions, new discoveries, tricks, bugs, and etc here or email me (check my profile)

[This message has been edited by Leif Ericson (edited 01-21-2012 @ 04:33 AM).]