Movement Directions (DIRECT_*)

Overview

Planet Blupi uses an 8-direction system. Direction values are multiples of 16, a design inherited from the animation phase counter (historically the direction was encoded in the high bits of an action+phase counter).

All direction constants are defined in include/def.h.

Direction Compass

        DIRECT_NO (80)
   DIRECT_O (64)    DIRECT_N (96)
         \    |    /
          \   |   /
           \  |  /
DIRECT_SO(48)--o--DIRECT_NE (112)
           /  |  \
          /   |   \
         /    |    \
   DIRECT_S(32)    DIRECT_E (0)
        DIRECT_SE (16)

Note: In the isometric view, "East" (DIRECT_E) visually points toward the bottom-right, and "North" (DIRECT_N) toward the upper-right.

Direction Constants

Constant	Value	Compass	Grid delta (dx, dy)
`DIRECT_E`	0	East	(+1, 0)
`DIRECT_SE`	16	South-East	(+1, +1)
`DIRECT_S`	32	South	(0, +1)
`DIRECT_SO`	48	South-West	(-1, +1)
`DIRECT_O`	64	West	(-1, 0)
`DIRECT_NO`	80	North-West	(-1, -1)
`DIRECT_N`	96	North	(0, -1)
`DIRECT_NE`	112	North-East	(+1, -1)

Direction in Blupi Struct

short aDirect;   // current direction (DIRECT_*)
short sDirect;   // desired direction (the character will rotate toward it)

CDecor::BlupiRotate(rank) advances aDirect one step toward sDirect each tick, creating smooth rotation animation.

Direction Helper Functions

POINT GetVector(int direct);
// Converts a DIRECT_* value to a (dx, dy) cell offset vector.
// Example: GetVector(DIRECT_NE) = {+1, -1}

int CDecor::DirectSearch(POINT cel, POINT goal);
// Returns the DIRECT_* value that best points from cel toward goal.
// Uses Manhattan distance heuristic, returns the closest cardinal/diagonal direction.

Direction in Action Codes

Animation sprites use direction as part of the action sprite selection. For example, ACTION_MARCHE in direction DIRECT_E uses different sprite frames than ACTION_MARCHE in direction DIRECT_S.

The action.cpp sprite tables are indexed by (action, aDirect / 16) to get the correct frame sequence.

4-direction vs 8-direction

Most movement uses all 8 directions, but some actions only have 4 directional variants (the cardinal directions only: E, S, O, N). Diagonal movement for such actions falls back to the nearest cardinal direction.