code/__DEFINES/directions.dm 
| NO_DIRECTION | define purely for readability, cables especially need to use this as NO_DIRECTION represents a "node" |
|---|---|
| FLIP_DIR_HORIZONTALLY | Using the ^ operator or XOR, we can compared TRUE East and West bits against our direction, since XOR will only return TRUE if one bit is False and the other is True, if East is 0, that bit will return TRUE and if West is 1, then that bit will return 0 hence EAST (0010) XOR EAST|WEST (0011) --> WEST (0001) Flips a direction along the horizontal axis, will convert E -> W, W -> E, NE -> NW, SE -> SW, etc |
| FLIP_DIR_VERTICALLY | Flips a direction along the vertical axis, will convert N -> S, S -> N, NE -> SE, SW -> NW, etc |
| IS_DIR_DIAGONAL | for directions, each cardinal direction only has 1 TRUE bit, so 1000 or 0100 for example, so when you subtract 1
from a cardinal direction it results in that directions initial TRUE bit always switching to FALSE, so if you & check it
against its initial self, it will return false, indicating that the direction is straight and not diagonal
returns TRUE if direction is diagonal and false if not |
| IS_DIR_CARDINAL | returns TRUE if direction is cardinal and false if not |
| REVERSE_DIR | Inverse direction, taking into account UP|DOWN if necessary. |
| DIR_JUST_HORIZONTAL | returns TRUE if the direction is EAST or WEST |
| DIR_JUST_VERTICAL | returns TRUE if the direction is NORTH or SOUTH |
Define Details
DIR_JUST_HORIZONTAL
returns TRUE if the direction is EAST or WEST
DIR_JUST_VERTICAL
returns TRUE if the direction is NORTH or SOUTH
FLIP_DIR_HORIZONTALLY
Using the ^ operator or XOR, we can compared TRUE East and West bits against our direction, since XOR will only return TRUE if one bit is False and the other is True, if East is 0, that bit will return TRUE and if West is 1, then that bit will return 0 hence EAST (0010) XOR EAST|WEST (0011) --> WEST (0001) Flips a direction along the horizontal axis, will convert E -> W, W -> E, NE -> NW, SE -> SW, etc
FLIP_DIR_VERTICALLY
Flips a direction along the vertical axis, will convert N -> S, S -> N, NE -> SE, SW -> NW, etc
IS_DIR_CARDINAL
returns TRUE if direction is cardinal and false if not
IS_DIR_DIAGONAL
for directions, each cardinal direction only has 1 TRUE bit, so 1000 or 0100 for example, so when you subtract 1
from a cardinal direction it results in that directions initial TRUE bit always switching to FALSE, so if you & check it
against its initial self, it will return false, indicating that the direction is straight and not diagonal
returns TRUE if direction is diagonal and false if not
NO_DIRECTION
define purely for readability, cables especially need to use this as NO_DIRECTION represents a "node"
REVERSE_DIR
Inverse direction, taking into account UP|DOWN if necessary.