Function dig_corridor

src/sp_lev.c:2548–2663

* Dig a corridor between two points, using terrain ftyp. * if nxcor is TRUE, he corridor may be blocked by a boulder, * or just end without reaching the destination. * if not null, npoints has the number of map locations used */

 * if not null, npoints has the number of map locations used
 */
boolean
dig_corridor(
    coord *org, coord *dest,
    int *npoints,
    boolean nxcor,
    schar ftyp, schar btyp)
{
    int dx = 0, dy = 0, dix, diy, cct;
    struct rm *crm;
    int tx, ty, xx, yy;

    if (npoints)
        *npoints = 0;
    xx = org->x;
    yy = org->y;
    tx = dest->x;
    ty = dest->y;
    if (xx <= 0 || yy <= 0 || tx <= 0 || ty <= 0 || xx > COLNO - 1
        || tx > COLNO - 1 || yy > ROWNO - 1 || ty > ROWNO - 1) {
        debugpline4("dig_corridor: bad coords <%d,%d> <%d,%d>.",
                    xx, yy, tx, ty);
        return FALSE;
    }
    if (tx > xx)
        dx = 1;
    else if (ty > yy)
        dy = 1;
    else if (tx < xx)
        dx = -1;
    else
        dy = -1;

    xx -= dx;
    yy -= dy;
    cct = 0;
    while (xx != tx || yy != ty) {
        /* loop: dig corridor at [xx,yy] and find new [xx,yy] */
        if (cct++ > 500 || (nxcor && !rn2(35)))
            return FALSE;

        xx += dx;
        yy += dy;

        if (xx >= COLNO - 1 || xx <= 0 || yy <= 0 || yy >= ROWNO - 1)
            return FALSE; /* impossible */

        crm = &levl[xx][yy];
        if (crm->typ == btyp) {
            if (ftyp == CORR && maybe_sdoor(100)) {
                if (npoints)
                    (*npoints)++;
                crm->typ = SCORR;
            } else {
                if (npoints)
                    (*npoints)++;
                crm->typ = ftyp;
                if (nxcor && !rn2(50))
                    (void) mksobj_at(BOULDER, xx, yy, TRUE, FALSE);