A map is just a bunch of terrain strings arranged in a rectangle (the rectangle is known as the "map data"). There are two ways to use this rectangle in a file: as a stand-alone map or within a scenario. The easiest way to create maps is just to use the built-in editor, but if you want to actually understand how maps work, you should read a little about the map data format. This page explains that format, and then has some pointers about the editor, saving files, and how to play on a map once you've made it. For instructions on how to distribute maps, see BuildingMapsDistribution.
Creating a map
Wesnoth has a fully functional map editor, accessible from within the game. The map editor should be fairly straightforward, however some helpful hotkeys can be found in the WesnothMapEditor article. Making good, balanced, interesting maps is another task altogether. ESR has addressed it in his Campaign Design How-To. If you run into trouble with the map editor, go ahead and ask for help on the Multiplayer Development forum.
If you're a programmer, note that while the source code and most binary distributions come with the official graphical map editor, you may have to give the build system a flag or argument to tell it to compile them as well as the main game.
Adding units and map descriptions
Campaign writers can't write campaigns without scenarios, so campaigns will always use scenario files. Multiplayer mapmakers, however, have a choice. If you want to place an object or unit on the map, you must create a scenario file starting with the [multiplayer] tag and containing the map_data key therein. The map_data key can either point to a standalone map file or include the raw map data in quotes inside the scenario file.
Using scenario files for multiplayer maps, you lose the simplicity of the standalone map file, but you gain tremendous power. With a scenario file, you can add units and objects, include a map description, and set default map settings like allies, starting gold, and experience modifiers. You can even create custom events. Check out BuildingScenarios, ScenarioWML, and BuildingMultiplayer for more information.
Map data format
This is not the Matrix. You normally don't need to look at encoded maps. However, if you would like to use some advanced terrain features or create scenarios and campaigns, you'll have to dive into the map code. The encoding for maps has a specific format in Wesnoth:
- A map starts with a header with the following keys
- usage, this should be 'map' for a map and 'mask' for an overlay mask
- border_size, the size of the border, should be 1 for map and 0 for mask. When the border_size is 1 the map border is part of the map data, this means the user can define the border instead of the game taking a guess.
- Between the header and the data should be 1 empty line
- A map data file consists of any number of lines, each with the same number of strings.
- Each string must be a string specified in a string key specifying a terrain (see TerrainLettersWML).
- Each string may be padded with spaces or tabs and must be separated with a comma, except for the last string on a line this one may not have a comma.
- When the file is interpreted, each string will be replaced by the terrain it refers to.
- Empty lines are allowed before, after and between lines of characters, between lines is not advised.
- Terrains may be prefixed with a number followed by one space, these indicate the starting position for side n. n = 1, 2, 3, ... 9 (more might work but is untested and unsupported). This is a change from the previous system where a starting position was automatically a keep.
It's advised to use spaces for padding and pad each column to be the same width; the game does this when writing a map file.
Since text file tiles are squares while game tiles are hexes, some tiles must be shifted. Tiles in even-numbered columns are shifted down 1/2 of a tile. For example, to have a road of connected dirt ('Re') tiles, the map data would look like this:
usage=map border_size=1 Re, Re, Gg, Gg, Gg, Gg, Gg, Gg Gg, Gg, Re, Re, Gg, Gg, Gg, Gg Gg, Gg, Gg, Gg, Re, Re, Gg, Gg Gg, Gg, Gg, Gg, Gg, Gg, Re, Re
So now what?
You've created an awesome map with the map editor and you're ready to test it out. But how can you do this? It's actually quite simple.
Play your map
If you just want to play the map, maybe against the computer or with a friend, all you have to do is save it into the map editor's folder (the default location). Then, when you launch the game and host a multiplayer game, the map should appear at the top of the map choices screen.
When creating a game on the multiplayer server, your map will be described to other players as a "Use Map" and any replays stored on the server will refer to the game as "Use Map."
For the curious: Saving a map file like this creates a stand-alone file that holds the map data. That file is by default saved in userdata/editor/maps/, and maps in that location are added to the top of the multiplayer map selection list.
When you're ready to share your map with the world, post it to the Multiplayer Development forum or package it to be distributed on the in-game add-ons server. For instructions on how to distribute maps, see BuildingMapsDistribution