Building Levels and Prerequisites

Now that I have gone through a few minor enhancements, I'm ready to start thinking about the building/tech tree.

It looks like there is really not much support for 'building levels' inside the RTS Pack, except for the multidimension array. Most functions have the building level hardcoded as index 0. Additionally, while there are resources needed to build a building, there isn't any provision for prerequisite buildings or technologies.

Prerequisites can be pretty diverse. For example, to build a level 3 Armory, you might need:
1X Level 3 townCenter
2X Level 2 Barracks
1X The Military Zog Permit

OK, I got a little wacky at the end to illustrate a point.
I think a good way to do this would be to define the prerequisites inside the datablocks of a building.
Some preliminary tests showed that I could do this in startPlaceBuilding, in the same area where a resourcespend check is done.

But that's getting a little ahead, because before we can Place a building, we would need to have an icon button to do it, and that button should only be enabled on a building's Build Menu if the prerequisites have been met.

So I have got to come up with a design that will work both ways, hopefully without reproducing a lot of the same code. It theoretically could be done in one place, before the button click, but that would introduce a window of time where the resources or prerequisites could drop below required amounts and we would still build the building. Not too cool, especially with a lot of reource traffic.

I am thinking about a data structure that would contain provisions for a good diverse bunch of prerequisites:
Element 0 = "BuildingName Datablockname BuildingLevel NumPrereqs"
Element 1..n = "prereqtype prereqname prereqlevel prereqamount"
Prereq[0] = "Armory ArmoryDataBlock 3 3"
Prereq[1] = "Building TownCenter 3 1"
Prereq[2] = "Building Barracks 2 2"
Prereq[3] = "Item MilitaryZogPermit 1 1"

In the gui side, where we build the BuildingMenu, we would look at the ActionList to see if the building could build any buildings (have to implement an 'upgrade', right now only 'hire' is really done) and run through the building datablock's prerequisite check to see if we even show the Upgrade button.

Note that the ActionType is defined on the client AND the server, and is kind of only geared towards one action with many arguments:
CLIENT: $BD_ActionType[1] = "Hire bonecracker shocker rifleman";
SERVER: $Buildings::ActionType[2,0] = "Hire bonecracker shocker rifleman";

Yargh! note that these are both for the same building, the indexes are not the same. So we've got to be extra careful not to mix things up later.

So we will need to be able to extend that a little to add more actions, so I would look more like:
"Hire bonecracker shocker rifleman upgrade armory"

Hmm. I dunno if that would work so well

I only want to extend this so I could make use of the existing actionicons code, but this might not be the best approach. That's it for now, I'm going to let it mull for awhile.

Please weigh in for implementation ideas!