About
The Metroid Map
In the Metroid game's program the world map is stored in a 32 by 32 grid of screen indices. The map does not specify which level each screen belongs to, only the screen index. This is important to understand. As you play the game and scroll from screen to screen the game simply loads the screens from the level you are currently in. When you go up or down an elevator the game loads data for a different level, and from that point on the game will display screens from the level you have newly entered. It infers which level each screen on the map belongs to.
Editroid's map, or the "editor map," uses color coding to indicate which level each screen belongs to. But this information is not taken from the ROM, since this information is not contained in the ROM in the first place. Editroid can not infer which level each screen belongs to, and, instead, includes a map of the original game which is used when you load a ROM that has not been previously edited. Your editor map is saved beside the game data every time you save changes to the ROM.
This means that simply changing the colors on the editor map in the map editor will not necessarily have any change in the game, and it is very possible for the map in the editor to show something different from what will be seen in the game. Even so, it is still important to edit the map in the map editor when you change the layout of the world. When a room is added to the map, the level it will belong to should be marked on the editor so that the editor will know which level's data to use when the screen is displayed and edited. It is also important to remove a screen from the editor map if it will no longer be used, in order to maintain organization.
Screens that appear black in color on the map are marked in the game data as inactive. During game play, the screen will not scroll into these rooms. If an unobstructed path leads to an inactive screen then the player can walk off the edge of the screen and will not be able to see Samus (and, most likely, won't be able to get back into the visible part of the level).
How To Use The Map EditorLeft-click a screen to bring it up for editing. If you want to remove a screen from the map, right-click it. To "paint" on the map, hold shift and then left-click on a square that is the color you want to paint with, and then, without lifting the button, drag the mouse to copy that color to adjacent map locations. To cycle an individual map location through different levels, hold shift and right-click that map location.