As with basically every programming tutorial on the globe, I'll begin where they all do - printing a message that says "Hello World!"
I'd like to quickly note that as this tutorial series progresses, I'm going to be helping less and less and explaining more and more. I don't want to hand-hold you through the entire project, and each lesson will include at least one "challenge", where I give you an objective and tell you to go do it. Self-guided teaching is important, and once you're done this tutorial series, you'll be expected to be at least remotely competent and able to work this stuff out independently. I highly recommend you stick to the challenges and give them a shot, they'll benefit you if you really want to get good with Lua.
Alright, within your text editor of choice, create a new file. Within that file, type the following block:
function testing_init() out("Hello World!") end
This is our first look at functions, which I'll go much further in detail about next lesson. "testing_init()" is a function, which does the "out("Hello World!") line when it's called. Likewise, "out("Hello World")" is a function of its own, and it prints the text within the brackets to a log.txt file, which CA uses for error-checking scripts and printing out details. We're using it for this first tutorial, but we'll see it many more times as we go on.
Save it, and save as "testing_init.lua" within your modding folder on your PC. Boom, your first Lua file. And you did it all by yourself!
Open up RPFM, and create a new packfile. Within the packfile, make the following script directory: "script/campaign/mod". Within the "/mod" folder, add your testing_init.lua file. Save it as whatever you'd like.
I mentioned that the "out()" function is a CA function that prints text onto a log.txt file, but I missed a detail - on retail, that log file is never made. So, what we need to do is go and download/enable the Script Debug Activator mod, by theSniperDevil, which enables the creation of that log file.
Now go grab your new .pack file, and drop it into Steam/steamapps/common/Total War WARHAMMER II/data (which will here-to-for be referred to as /data folder). Enable the .pack file with the mod manager of your choosing, load up the game, and load up a campaign.
In your game folder (Steam/steamapps/common/Total War WARHAMMER II), you should see a new file - script_log_DDMMYY_HHMM.txt. Open that up with a text editor, use find to search for "Hello World". If it's there, it worked, and if it isn't, something went fatally wrong! Go back and try again.
At this point, I'd like to quickly cover how CA loads and runs script mods for modders. There is a mod-script loader built into TW:WH2, and it's pretty simple for us to use. We can load our mods automatically in different game modes, using the following paths:
- Campaign (Mortal Empires): script/campaign/main_warhammer/mod
- Campaign (Vortex): script/campaign/wh2_main_great_vortex/mod
- Campaign (either): script/campaign/mod
- Battle (excluding quest-battles): script/battle/mod
- Frontend: script/frontend/mod
And lastly, there's one path that is available during all game modes, and loads before any of the other paths (so if you load campaign, and have a script in the following directory, it will be loaded before any in the script/campaign/mod directory). I must warn, though, that this directory should only be used if you're being very smart about what's within, making sure it's all game-mode-agnostic, or making sure you're checking for the game-mode within - you can't call the campaign_manager while in frontend, for instance!
- Lib: script/_lib/mod
Within each of these directories (barring the battle one), if you have a function named the same thing as the .lua file (like testing_init from our last example), it will be automatically called at an appropriate time. We'll talk more about what this means, and some alternatives to this method that I prefer, but for now we'll stick with it. Remember, if the function name matches the file name of the script, then it'll be run, except when it's in the /battle directory.
And time for your challenge. We're going to start from the top. Make a brand new pack, and a brand new script file, with a new name. Have this print out the text "Goodbye World!" on to the log file, as before. This time, however, make it print while in the frontend game mode (post-startup menus to select between Custom Battle/Campaign and what not).