A position is uniquely addressed by its room name (e.g., W5N5) and x-y coordinates within the room (from 0-49, where 0,0 is the top left corner.)
Internally, Screeps serializes the room position to a 32-bit integer called __packedPos.
Positions can theoretically be packed even more densely: it only takes 6 bits (0-63) to store each of the x-y coordinates, plus 7 or 8 bits (0-127 or 0-255 depending on the shard) for the x-y coordinates of the room itself, for a total of 26 bits.
It’s frequently useful to compare room positions in different rooms (for distance, e.g.) This algorithm combines the room coordinates with the position to get a global coordinate reference.
function roomPositionToCoords(pos: RoomPosition) {
let { x, y, roomName } = pos;
if (!_.inRange(x, 0, 50))
throw new RangeError("x value " + x + " not in range");
if (!_.inRange(y, 0, 50))
throw new RangeError("y value " + y + " not in range");
let { wx, wy } = roomNameToCoords(roomName);
return {
x: 50 * Number(wx) + x,
y: 50 * Number(wy) + y,
};
}
It should be noted that it’s faster to compute this from the __packedPos property.