wiki:Random_Map_Generator
Last modified 18 months ago Last modified on 2012-11-04 18:15:44

There is a random map generator integrated with the engine. Random map scripts (RMS) are implemented in Javascript with a minimal C++ interface, see Random Map Generator Internals.

Playing Random Maps

Random maps can now be played through the game setup, by choosing Random from the Match Type dropdown. See the Gameplay Manual for more details.

Guide to JavaScript

The game supports scripts written in Javascript, which are used for random maps, game logic, and AIs. The engine uses the SpiderMonkey library to implement the language. References for those interested in Javascript programming:

Guide to Random Map Scripting

Basically a random map script is responsible for all the logic of generating a map: modeling terrain, placing units and resources, and then returning the data to the engine. In practice, most of the logic is hidden by APIs also implemented in JavaScript. We have added the concept of libraries for this purpose.

Random map scripts are placed in the maps/random/ directory (see mod layout). In addition to the script itself, there is also an associated JSON data file. This file is loaded by game setup to recognize a new random map, and it includes various settings, see defining the map for details.

Load libraries

A random map script should first load any libraries it will need. Libraries are stored in the game data directories under maps/random/libraryName/. When a library is loaded, all scripts in that directory are parsed and their code made available to the random map script. They are loaded through the function call RMS.LoadLibrary(libraryName). Currently there is only one library available, rmgen - in the future there may be others or you can create your own.

Initialize the library

The next step is to initialize the library. This may vary, but for rmgen, you would call InitMap().

Save the results

The random map script should end with a call to RMS.ExportMap(data), which returns all the map data back to the engine. In rmgen this is abstracted by a call to ExportMap(). For the exact format of the data see Random Map Generator Internals.

Note: The export map function does a coordinate conversion from the 2D used in the rmgen libs to 3D for the engine. You should only use it once, only after the map is fully generated.

Design Tips and Conventions

  • Place terrain over an area rather than a tile. Most times placing tiles only looks unnatural. In addition remember terrain from the same biome fits better to each other than tiles from different biomes.
  • In a player's starting area, not many obstructions should be placed within a radius of 20 tiles, so the player has space to build a base there. Large clumps of trees can be problematic. Especially avoid placing very uneven terrain and water there. Remember that Iberians get walls as a civilization bonus which are placed by default with their starting entities and have roughly a radius of 20 tiles.
  • A player's starting buildings should be rotated uniformly to face the player's initial camera view. A rotation of about -PI/4 on the Y-axis is standard. Starting units should be grouped together neatly.
  • Placed entities (especially trees) shouldn't obstruct the player's initial view of their units and structures.
  • Don't place entities outside the reachable map area (That causes problems with AIs).
  • Match the aesthetics of hand-crafted scenarios as much as possible.

Available Libraries

Here's a list of libraries currently included with the map generator: