Posted on Apr 30, 2022

Open Source Adventures: Episode 48: Extracting DLC data from BATTLETECH

I tried various tools to extract data from heavymetal DLC.

DisUnity

First I tried DisUnity - but that's an abandoned project, and it doesn't work with current version.

Unity Asset Bundle Extractor

Next I tried Unity Asset Bundle Extractor which is very nonintuitive but it extracted what I want. "Select All" doesn't work, I needed to select first item, then shift click on the last item. Then I pressed "Export Raw".

It unfortunately created files like: weapon_autocannon_lb10x_0_stock.json-CAB_81519cd4dc355e215c567f814d1dd677--9084477644472635856.dat instead of weapon/autocannon_lb10x_0_stock.json.

They also some weird crap at start and end of each file. It wouldn't be too difficult to strip, but I hoped for just the proper data.

"Dump as text file" and "Dump as json file" options were even worse. Finally "Plugins > Export to .txt" worked.

Unity Asset Bundle Extractor has all information necessary to get it right, it just choses not to.

Organizing the files

The files still had stupid names like weapon_autocannon_lb10x_0_stock.json-CAB_81519cd4dc355e215c567f814d1dd677--9084477644472635856.txt.

So I did a quick:

$ rename 's/-CAB_.*//' *.txt

After that I moved weapon files to heavymetal/weapon/*.json. I might need to organize other files like ammo etc. later.

Fortunately that's the only DLC with extra weapons. If I wanted to analyze all mechs, I'd need to repeat the same steps with other DLCs.

Script

#!/usr/bin/env ruby require "json" require "memoist" require "pathname" require "pry" class Weapon extend Memoist attr_reader :data def initialize(path) @data = JSON.parse(path.read) end memoize def name bonuses = [bonus_a, bonus_b].compact if bonuses.empty? base_name else "#{base_name} (#{bonuses.join(", ")})" end end memoize def base_name [ data["Description"]["Name"], data["Description"]["UIName"], ].compact.last.gsub(" +", "+") end memoize def bonus_a data["BonusValueA"] == "" ? nil : data["BonusValueA"].gsub(/[a-z]\K\./, "") end memoize def bonus_b data["BonusValueB"] == "" ? nil : data["BonusValueB"].gsub(/[a-z]\K\./, "") end def category @data["Category"] end def tonnage @data["Tonnage"] end def damage shots * base_damage end def base_damage @data["Damage"] end def shots @data["ShotsWhenFired"] end def heat @data["HeatGenerated"] end def heat_tonnage heat / 3.0 end def ammo_tonnage # TODO 0 end def total_tonnage tonnage + heat_tonnage + ammo_tonnage end def ammo_category @data["ammoCategoryID"] end def purchasable? @data["Description"]["Purchasable"] end end class BattleTechGame extend Memoist def initialize(game_root, *dlc_roots) @game_root = Pathname(game_root) @dlc_roots = dlc_roots.map{|path| Pathname(path)} end memoize def data_root @game_root + "BattleTech_Data/StreamingAssets/data" end memoize def weapon_files [data_root, *@dlc_roots] .flat_map{|root| root.glob("weapon/*.json")} .select{|n| n.basename.to_s != "WeaponTemplate.json"} end memoize def weapons weapon_files.map{|path| Weapon.new(path)} end def print_weapons_report weapons .select{|w| w.category != "Melee" and w.name != "AI Laser"} .sort_by{|w| [w.damage.to_f / w.total_tonnage, w.damage, w.name] } .reverse .each{|w| puts "* #{w.name}: #{w.damage} / #{w.total_tonnage.round(2)}" } end end game = BattleTechGame.new(*ARGV) game.print_weapons_report

To run the scirpt I use ./weapons /path/to/battletech /path/to/heavymetal

Result

Here's the result. As the script still doesn't count ammo, it overvalues ammo using weapons. It's also quite confused by any weapon that has special effects like all those TAGs and NARCs and COILs on the end of the list. It might be best to just exclude them the analysis.