6.370 Home: Background: Primer: Maps & Terrain

The map is the virtual world where units, buildings, and resources can coexist not-so-peacefully. It serves as a coordinate space to locate other game components as they change over time; it remains constant and therefore does not have state. In the game's storyline, it probably translates into a physical 2D area or 3D volume inhabited by units, buildings, and resources, so it is usually texture-mapped or tiled appropriately to look like real grass, water, or outer space. Every instance of an RTS game has a unique map associated with it that does not change from start to finish. The map represents a particular set of constraints which are called terrains.

Macro View of Map		Micro View of Map

Although terrain implies dirt, I use terrain to mean a subset of the map which represents a constraint on where types of units can move. Terrains also affect combat relationships as described in the Units & Abilities section. Common types of terrains are flat land, mountains, water, and air. In the first image below, a scout can cross a river while an archon cannot. In the second image, a shuttle can transport dragoons across the river; in this case, the water and the shuttle together are just another constraint on the movement of dragoons.

Air units can go where land units fear to tread.		Air units can also stop being assholes and give their ground-hugging brethren a lift.