For a map I am making, I would like to prevent the player from making a factory until they get to a certain part of the map. They are always able to make a barracks, which I don't want to change. A simple solution seemed to be just making factories cost gas as well as minerals and just giving the player gas when they get to this location, but I also want to selectively add the starport when they get to a different, later location, so the gas method would not work.

Here's the rundown of what I want to have happen:
Player starts off in location 1 and is able to make CCs and Barracks.
Player enters location 2 and can now build Factories.
Player enters location 3 and can now build Starports.

One possible solution that I thought of, but don't like, is having a beacon in location 2 where a player can bring some units (SCVs or marines, for example) and exchange them for a tank, eliminating the need for a factory all together. This is a very roundabout way of doing what I have in mind.

I have been making this in Blizzard's editor so far without trouble, but I have used SCMDraft before and can find my way around that tool if it's required to get this done. If you have any ideas on how to implement this system, please let me know. I would like to use an elegant solution, but a less-than-ideal solution like the one I mentioned above is better than nothing. I am familiar with how triggers work, so you can give it to me straight.

Well, this might be a less-than-ideal solution, but it's a thought. You could make a switch that kills whatever building you're trying to prevent them from building at anywhere and refunds their money. Once they get to the given location just disable the switch.

Yeah, I think that solution is probably the most effective. Tech tree work-arounds are pretty annoying :\

Another thought of mine would be to disable the structures in the tech tree and preplace them as neutral units and give them to the players when they've reached the given location.

the problem with that would be that you would still command a barracks or what have you, enableing one to build a factory

nowwhat i would do is make a death counter that contrals progress through the map

that can have many uses for you not just as a method for this

Condition
Bring Factory
Player has at most "x" death counts
Action
Remove all factory owned by player at anywhere
perserve trig

paired with hyper triggers that should make it go fairly quick,also u can display text telling them not to make it
now of course when player reachs location x, then u add to the death counter enabling them to build it

or

you could have the buidings swap with a equal protoss building

then upon build whatever unit, you switch back into terran

so it would be just like supply depot to bunker system, only now ur using barracks to gateway, factory to robotics facility, or starport to stargate
you would then have to give them a prerequisite for the factory when they reach that part of the level, but not in their vision
also, a simple way to not have ot make a plyon for everything is just set the doodad state to enabled and it show power the building

or

you could go with the gas feature and ur level is 1, you have x amount of gas, then u level up and u get x more gas

make barracks cost 1 gas, factory 2, starport 3 etc.



theres just a couple ways to manage this, and i had another way but i forgot it lol, ill get back to u if i remeber it

Why does the gas solution not work?
Tech Level 0: Player's Gas always set to 0 - Buildings available: Barracks (costs 0 gas)
Tech Level 1: Player's Gas always set to 1 - Buildings available: Factory (costs 1 gas)
Tech Level 2: Player's Gas always set to 2 - Buildings available: Starport (costs 2 gas)

EDIT: oops just realized that Tooth already mentioned this as his last solution

Tooth and NudeRaider, I had not thought of that method of using gas. What an excellent solution, thank you both! The reason I dismissed gas originally was because I was only thinking of gas as being something constantly collected, meaning any cost limit would be able to be broken too early, or would be too difficult to reach later in the game. That 0, 1, 2 gas solution is a great way to solve it. When I said "give them gas," I meant give them a geyser. Giving them a constant amount of gas had not crossed my mind, but it will work beautifully. Thanks to everyone who replied to this thread.

If it's disabled you can't build it no matter what.

Disabling the structure in the tech tree, not the building itself, completely takes the build option for that structure off your build menu when using an scv, regardless of what prerequisite buildings you might have.

yeah i read over that too fast i didnt realize it said disable it from the tree