Using LUA to prevent unit upgrade?

[sman1975]

Greetings,

I'm working on a mod that adds units throughout the tech tree, for example, it adds 8 UUs, one for each Era of the normal game.

I'd like to make it possible to upgrade a unit to the next Era's version, once a civ discovers the prereq tech (pretty easy to do).

I'd also like to limit the number of each Era's units (also easy to do using the MaxPlayerInstances element).

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My problem is that I'd like to limit the total number of units at 3 for each Era, for a max of 24 total units, assuming you never upgraded any units.

Unfortunately, when it's possible to upgrade a unit, the game lets you do this - and does not check the MaxPlayerInstances numbers before upgrading the unit.

This means I can build 3 "ancient" units. When I get to "classical" I can build 3 "classical" units, then upgrade the 3 "ancient" units. I now have 6 "classical" units.

Ultimately, I can end up with 24 "Information" units if I plan accordingly. This is definitely game breaking, as these latter units are pretty OP.

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I can think of some LUA ways of preventing a player for "producing" a given Era unit if there are already too many fielded. But I still can't figure out a way of preventing an upgrade if there are too many of that Era's units already in the game.

Does anyone have any suggestions on how to pull this off?

Thanks!

 

[whoward69]

See here - https://forums.civfanatics.com/threads/bnw-patch-version-1-0-3-276-new-lua-hooks.537056/

You want the "CanHaveAnyUpgrade" event. (This was one of the events that I first added with my VMC DLL, that Firaxis adopted in a later patch)

Search these forums for more details/examples.

 

[sman1975]

Thank you, Mr. whoward69! I didn't see this event in the modiki, and forgot to look at that extended list of events in the reference you sent. Great tip, BTW!

I looked over the example in your "Units - Multiple Upgrades" mod. Here is the admittedly bare-bones/suboptimal solution I got working. It limits a civ's ability to upgrading units to a total of 3 of the higher unit. I'll expand it later to put in the limits on specific units later, but here is the basic function:

g_iTotalUnitsPerClass = 3

function OnCanHaveAnyUpgrade(iPlayer, iUnit)                                                                    -- Function determines if an upgrade is possible, based on number of higher units
    local pPlayer = Players[iPlayer]                                                                        -- Set the player pointer
    local pUnit = pPlayer:GetUnitByID(iUnit)                                                                -- Set the unit pointer
    local iUpgradeUnitType = pUnit:GetUpgradeUnitType()                                                        -- Get the upgrade unit type
    local iUpgradeUnitClass = GameInfo.Units[iUpgradeUnitType].Class                                        -- Get the class of the upgrade unit
    local iUpgradeUnitClassType = GameInfo.UnitClasses["" .. iUpgradeUnitClass .. ""].ID                    -- Convert the class key to the ID
    local iUpgradeUnitClassCount = pPlayer:GetUnitClassCount("" .. iUpgradeUnitClassType .. "")    or g_iTotalUnitsPerClass        -- Get the total upgrade unit class count        
    if iUpgradeUnitClassCount >= g_iTotalUnitsPerClass then                                                    -- If the number of upgrade units is more than the amount allowed, then...
        return false                                                                                        -- Return false: no more upgrades are allowed
    end
    return true                                                                                                -- Return true, if the number of upgrade units is less than the limit
end
GameEvents.CanHaveAnyUpgrade.Add(OnCanHaveAnyUpgrade)

The function works exactly as I want it to, except for one small UI problem: the tooltip on the Unit Panel on the now grayed-out "upgrade" button. It shows the same text as it does when there's no restriction on upgrading the unit.

Here is a picture of the issue:



Is there any way, short of replacing UnitPanel.lua, to update that tooltip with a "too many units" error message, or simply call it "good enough" and then a day?

Thanks!

 

[LeeS]

1. Somewhat simplified

   g_iTotalUnitsPerClass = 3
   
   function OnCanHaveAnyUpgrade(iPlayer, iUnit)							-- Function determines if an upgrade is possible, based on number of higher units
       local pPlayer = Players[iPlayer]								-- Set the player pointer
       local pUnit = pPlayer:GetUnitByID(iUnit)							-- Set the unit pointer
       local iUpgradeUnitType = pUnit:GetUpgradeUnitType()						-- Get the upgrade unit type
       local sUpgradeUnitClass = GameInfo.Units[iUpgradeUnitType].Class				-- Get the class of the upgrade unit
       local iUpgradeUnitClassCount = pPlayer:GetUnitClassCount(GameInfoTypes[sUpgradeUnitClass])	-- Get the total upgrade unit class count        
       if iUpgradeUnitClassCount >= g_iTotalUnitsPerClass then					-- If the number of upgrade units is more than the amount allowed, then...
           return false										-- Return false: no more upgrades are allowed
       end
       return true											-- Return true, if the number of upgrade units is less than the limit
   end
   GameEvents.CanHaveAnyUpgrade.Add(OnCanHaveAnyUpgrade)

2. You don't need the syntax like here

   "" .. iUpgradeUnitClass .. ""

   You can directly state the viariable name you have inserted either a text string or an ID # into, so long as the string or the ID # exists within the table.
3. If you did this you'd get a nil value error because there's no such thing as UNIT_CHEESEBURGLER

   local iUnitType = GameInfoTypes.UNIT_CHEESEBURGLER
   local sUnitClass = GameInfo.Units[iUnitType].Class
   local iUnitClassID = GameInfoTypes[sUnitClass]
   print(iUnitClassID)

   But this is fine

   local iUnitType = GameInfoTypes.UNIT_SWORDSMAN
   local sUnitClass = GameInfo.Units[iUnitType].Class
   local iUnitClassID = GameInfoTypes[sUnitClass]
   print(iUnitClassID)

4. For the issue with the unit panel, you'd have to re-write the unit-panel lua file

 

[sman1975]

@LeeS - appreciate the help optimizing the code. I put in the changes and, surprise-surprise, it worked beautifully...

And thanks also for letting me know what I had suspected: there simply isn't a way to update that "upgrade unit" tooltip without rewriting the UnitPanel.lua. I know that a lot of mods replace that UI already, so one should only add a change like that if it's somehow worth breaking compatibility with a vast number of very popular mods. In this particular case (an inadequate tooltip), it's not.

Thanks again - appreciate the help learning how to write better code!