You would use a requirement to restrict the building. I highly recommend you search this site (particularly the tutorials section) for information on how to achieve this.
No, you can use requirements to allow or disallow building as you see fit.
For example, say you only want someone to be able to build one command center. You would create this requirement:
Use>NOT>Count Unit Command Center Queued or better.
There you go.
Edit: Here's a great place for you to learn everything you'll need to complete your project. Take some time and view these video's by OneTwo. He's put a lot of time into showing people how to achieve the very things you're asking about. I hope you find it helpful.
Take a look at the default campaign requirements. That's what showed me what to do. But I'll explain it a little more clearly.
Create a new requirement
Double-Click the "Requirement +" field
In the new dialog that opens, you have 2 folders: Use, and Show. Right-click "Use" and click "Add Requirement Node". A green folder that says "And" will appear. Click on this to highlight it.
To the right of the "And", there is a field called "Type", it is a drop down list. Click this, and choose the option that says "Not". This will change the folder "And" to a folder "Not".
Right click the "Not" folder, and click "Add Requirement Node" again.
Change type drop-down to be "Count Unit". This will add 2 more drop-downs immediately below the type drop-down.
In the drop-down named "Alias", find the command center in the list, and select it.
In the drop-down called "State", choose the option called "Queued or Better"
You're done. Click ok, and add this requirement to the build command center ability. What it does is this: If there is no command center for the player that owns the selected scv, then the scv can build one. But if one is built or has started building, the button will gray out and deactivate. This is a fairly simple concept, and, again, I highly recommend you research your questions before you ask, as there is a tutorial on this site that goes over this exact issue in detail. You will find people a lot more people willing to help you if you research before posting.
Just create the text actor and its associated mover when you get the income from the tower which you will probably do with a modify unit effect. So use an effect event to trigger the creation of the text actor. Also I advise actually looking at the automated refinery actors.
I'm making a base defense map and I want so you can only build the Income Tower (The Tower that gives minerals) Once!
How would I do this?
@tohaaaa: Go
You would use a requirement to restrict the building. I highly recommend you search this site (particularly the tutorials section) for information on how to achieve this.
@Snappybean: Go
YEah But I also want to make it so you can only make it once a requirement only makes it build able! Right?
You can easily combine 2 requirements, just add both of the conditions to one requirement, connected with an And - node.
As of how to restrict the building to one, check the Mothership-requirement, which is just the same thing.
@Kueken531: Go
Ok one more thing
How would I make it so when the Tower generates Minerals a +2 text hovers above it?
I looked at automated refinery but found nothing :(
@tohaaaa: Go
No, you can use requirements to allow or disallow building as you see fit.
For example, say you only want someone to be able to build one command center. You would create this requirement:
Use>NOT>Count Unit Command Center Queued or better.
There you go.
Edit: Here's a great place for you to learn everything you'll need to complete your project. Take some time and view these video's by OneTwo. He's put a lot of time into showing people how to achieve the very things you're asking about. I hope you find it helpful.
http://www.youtube.com/user/OneTwoSC#p/p
@Snappybean: Go
I dont understand that part
Can you please tell me where to put
Use>NOT>Count Unit Command Center Queued or better
Oh and BTW the map is a 4player one!
@tohaaaa: Go
Take a look at the default campaign requirements. That's what showed me what to do. But I'll explain it a little more clearly.
You're done. Click ok, and add this requirement to the build command center ability. What it does is this: If there is no command center for the player that owns the selected scv, then the scv can build one. But if one is built or has started building, the button will gray out and deactivate. This is a fairly simple concept, and, again, I highly recommend you research your questions before you ask, as there is a tutorial on this site that goes over this exact issue in detail. You will find people a lot more people willing to help you if you research before posting.
Hope this helps.
@Snappybean: Go
Ok 1 more thing
How would I make it so when every time Income Tower makes minerals a + 1 appears over it? And Fades?
@tohaaaa: Go
Take a look at those tutorials I posted, specifically the zerg defense ones. That will give you all the tools you need.
@Snappybean: Go
Can you please give me a direct link?
Look at the automated refinery text kicker actor.
Contribute to the wiki (Wiki button at top of page) Considered easy altering of the unit textures?
https://www.sc2mapster.com/forums/resources/tutorials/179654-data-actor-events-message-texture-select-by-id
https://media.forgecdn.net/attachments/187/40/Screenshot2011-04-17_09_16_21.jpg
@DrSuperEvil: Go
I cant find such an actor I only got
Automated Refinery FireSupressionBots TerranFlamesMediumBuilding
Ok I found it but now how do I make it so It shows up on the sensor tower
Look what created it and how it operates. Do we have to do all the thinking for you?
Contribute to the wiki (Wiki button at top of page) Considered easy altering of the unit textures?
https://www.sc2mapster.com/forums/resources/tutorials/179654-data-actor-events-message-texture-select-by-id
https://media.forgecdn.net/attachments/187/40/Screenshot2011-04-17_09_16_21.jpg
NO But how do I put that actor into my Income tower? And how do I display it like how do I sync it!
I am new to this so thats why I ask these questions
Just create the text actor and its associated mover when you get the income from the tower which you will probably do with a modify unit effect. So use an effect event to trigger the creation of the text actor. Also I advise actually looking at the automated refinery actors.
Contribute to the wiki (Wiki button at top of page) Considered easy altering of the unit textures?
https://www.sc2mapster.com/forums/resources/tutorials/179654-data-actor-events-message-texture-select-by-id
https://media.forgecdn.net/attachments/187/40/Screenshot2011-04-17_09_16_21.jpg
I'd just create a text tag with triggers and then add velocity & a timed duration. Have you considered that? It might be easier than doing it in data.
Ahhh I'm new to this SO I would appreciate some sort of guide?