/* fill the grid, starting from the origin until we reach the destination */
static void TCOD_path_set_cells(TCOD_path_data_t *path, int cutoff) {
int stepstaken = 0;
while ( path->grid[path->dx + path->dy * path->w ] == 0 && ! TCOD_list_is_empty(path->heap) ) {
stepstaken++;
if (stepstaken > cutoff)
break;
int x,y,i,imax;
float distance;
TCOD_path_get_cell(path,&x,&y,&distance);
imax= ( path->diagonalCost == 0.0f ? 4 : 8) ;
for (i=0; i < imax; i++ ) {
/* convert i to dx,dy */
static int idirx[]={0,-1,1,0,-1,1,-1,1};
static int idiry[]={-1,0,0,1,-1,-1,1,1};
/* convert i to direction */
static dir_t prevdirs[] = {
NORTH, WEST, EAST, SOUTH, NORTH_WEST, NORTH_EAST,SOUTH_WEST,SOUTH_EAST
};
/* coordinate of the adjacent cell */
int cx=x+idirx[i];
int cy=y+idiry[i];
if ( cx >= 0 && cy >= 0 && cx < path->w && cy < path->h ) {
float walk_cost = TCOD_path_walk_cost(path,x,y,cx,cy);
if ( walk_cost > 0.0f ) {
/* in of the map and walkable */
float covered=distance + walk_cost * (i>=4 ? path->diagonalCost : 1.0f);
float previousCovered = path->grid[cx + cy * path->w ];
if ( previousCovered == 0 ) {
/* put a new cell in the heap */
int offset=cx + cy * path->w;
/* A* heuristic : remaining distance */
float remaining=(float)sqrt((cx-path->dx)*(cx-path->dx)+(cy-path->dy)*(cy-path->dy));
path->grid[ offset ] = covered;
path->heur[ offset ] = covered + remaining;
path->prev[ offset ] = prevdirs[i];
TCOD_path_push_cell(path,cx,cy);
} else if ( previousCovered > covered ) {
/* we found a better path to a cell already in the heap */
int offset=cx + cy * path->w;
path->grid[ offset ] = covered;
path->heur[ offset ] -= (previousCovered - covered); /* fix the A* score */
path->prev[ offset ] = prevdirs[i];
/* reorder the heap */
heap_reorder(path,offset);
}
}
}
}
}
}
bool TCOD_path_walk(TCOD_path_t p, int *x, int *y, bool recalculate_when_needed) {
int newx,newy;
float can_walk;
int d;
TCOD_path_data_t *path=(TCOD_path_data_t *)p;
TCOD_IFNOT(p != NULL) return false;
if ( TCOD_path_is_empty(path) ) return false;
d=(int)(uintptr)TCOD_list_pop(path->path);
newx=path->ox + dirx[d];
newy=path->oy + diry[d];
/* check if the path is still valid */
can_walk = TCOD_path_walk_cost(path,path->ox,path->oy,newx,newy);
if ( can_walk == 0.0f ) {
if (! recalculate_when_needed ) return false; /* don't walk */
/* calculate a new path */
if (! TCOD_path_compute(path, path->ox,path->oy, path->dx,path->dy) ) return false ; /* cannot find a new path */
return TCOD_path_walk(p,x,y,true); /* walk along the new path */
}
if ( x ) *x=newx;
if ( y ) *y=newy;
path->ox=newx;
path->oy=newy;
return true;
}