actual bugs found:
* backwards_compatibility.lua (undeclared global "helper")
* core.lua (use of undeclared global "helper")
* wml_tags.transform_unit had wrong code to deal with recall_cost
* wrong variable name in cave_map_generator
The syntax is mostly the same as the old cave generator - a [scenario]
tag for general scenario data, and an [items] subtag of [chamber] for
chamber-specific data. However, the generator assumes that map locations
(from [item_location]) will be used and thus does not support
same_location_as_previous=yes in moveto events within [items].
This accomplishes two main things:
- Creates a mapgen_helper.lua module containing functions useful for Lua map generators
- Paves the way for allowing the cave generator to produce scenarios and accept user configuration
This map generator is used in HttT 17 and SoF 4. which needed to be updated aswell.
With this we finally have a lua generator that is used in mainline and that
can be used an an example by wml authors who want to write other map generators.
Unfortunateley there are still umc add ons in 1.12 that use
scenario_generation=cave so i didn't remove the cpp implementation yet.
