Function migrate_to_level

src/dog.c:886–932

}

void
migrate_to_level(
    struct monst *mtmp,
    xint16 tolev, /* destination level */
    xint16 xyloc, /* MIGR_xxx destination xy location: */
    coord *cc)   /* optional destination coordinates */
{
    d_level new_lev;
    coordxy xyflags;
    coordxy mx = mtmp->mx, my = mtmp->my; /* <mx,my> needed below */
    int num_segs; /* count of worm segments */

    if (mtmp->mleashed) {
        mtmp->mtame--;
        m_unleash(mtmp, TRUE);
    }

    /* prepare to take mtmp off the map */
    num_segs = mon_leave(mtmp);
    /* take off map and move mtmp from fmon list to migrating_mons */
    relmon(mtmp, &gm.migrating_mons); /* mtmp->mx,my retain their value */
    mtmp->mstate |= MON_MIGRATING;

    new_lev.dnum = ledger_to_dnum((xint16) tolev);
    new_lev.dlevel = ledger_to_dlev((xint16) tolev);
    /* overload mtmp->[mx,my], mtmp->[mux,muy], and mtmp->mtrack[] as
       destination codes */
    xyflags = (depth(&new_lev) < depth(&u.uz)); /* 1 => up */
    if (In_W_tower(mx, my, &u.uz))
        xyflags |= 2;
    mtmp->wormno = num_segs;
    mtmp->mlstmv = svm.moves;
    mtmp->mtrack[2].x = u.uz.dnum; /* migrating from this dungeon */
    mtmp->mtrack[2].y = u.uz.dlevel; /* migrating from this dungeon level */
    mtmp->mtrack[1].x = cc ? cc->x : mx;
    mtmp->mtrack[1].y = cc ? cc->y : my;
    mtmp->mtrack[0].x = xyloc;
    mtmp->mtrack[0].y = xyflags;
    mtmp->mux = new_lev.dnum;
    mtmp->muy = new_lev.dlevel;
    mtmp->mx = mtmp->my = 0; /* mx==0 implies migrating */

    /* don't extinguish a mobile light; it still exists but has changed
       from local (monst->mx > 0) to global (mx==0, not on this level) */
    if (emits_light(mtmp->data))
        vision_recalc(0);
}

/* when entering the endgame, levels from the dungeon and its branches are
   discarded because they can't be reached again; do the same for monsters