Packages may consist of following files:
- mod.py - main file required by Mod Handler. Includes unique name and version of package. Lists all related files included in mod.
- Script defining new objects and requesting Mod Handler to put them in game.
- Graphics files
- Sound files
- Additional Python script files (.py)
- Additional text files
- Possibly .json files
All files should be placed within the scope of root folder of mod.py file. Mods folder in main VCMI directory is scanned upon entering "new game" menu in search of mod.py files.
In order to ensure compatibility and ease of maintenance, all pacages should follow Package folder structure.
Adding new objects
Currently, all handlers load object configuration from game files at application launch. This needs to be separated into basic initialization of engine at application launch and dynamic management of avaliable mods in main menu as well as reconfiguration and dynamic loading of files at game start.
An example pseudo-code in Python for adding new artifact:
art = CreateArtifact( 'CrystalOrb', #reference name 'Crystal Orb', #actual name in game Artifact.ART_RELIC, #rarity from namespace Atifact Artifact.ART_HERO, #artifact type (including combined artifacts, commander or creature art) Artifact.ARTPOS_MISC #slot ) art.AddBonus (Bonus.SIGHT_RADIOUS,+12) #using namespace Bonus (in Python they are called packages and modules, but that's confusing) art.price = 8000 art.AIValue = 12000 art.description = ParseTextFile ('.\CrystalOrb.txt') SetArtifactDef ('CrystalOrb','.\lodfile\orb.def') id = ArtHandler.addArtifact ('CrystalOrb') # we get unique ID of that object ArtHandler.setArtAvaliable(id, true) #Artifact can be found in game at random localID = package.addArtifact('CrystalOrb'); # we get local ID which may be used to refer from other package or script
Some game objects, such as adventure map buildings may require completely new mechanics. In such case an explicit script function is needed to handle them.
Artifact may have a list of functions associated with certain game event(triggers). For example, a function is called when artifact is equipped, at the beginning of battle, at the beginning of each turn etc. This system uses same type of Triggers as ERM scripts, possibly with addition of new ones. All these functions need to be listed somewhere. For example, a class inherited from CArtifact may have a colection of functions associated with every possible trigger, or void. This of course causes redundancy, but the cost may be not significant.
Adventure map objects
Every adventure object acts in a different way. It's not possible to present their behaviour in a form of parameters or property sheet. It is possible with Python to export some base C++ object classes, such as CPlayersVisited or CArmedInstance to Python classes and ask modders to derive new sub-classes from them, overriding existing functions. This approach requires existence of clear structure of abstract base classes and separating interface from actual behaviour. Currently one class (for example CGVisitableOPH) handles behaviour of many evidently different objects with different ID, such as Tree of Knowledge, Library of Enlightenment AND Arena. This structure is hardcoded and not useful for modders.
There are two types of configuration for a package:
- Setting the value of variable, numerical or boolen (on/off)
- Grouping objects which can be turned on and off at the same time for convenience.