bool grid_see_grid(int posx_1, int posy_1, int posx_2, int posy_2,
                   dungeon_feature_type allowed = DNGN_UNSEEN);

// By default, it excludes enpoints from the count.

// By default, it excludes end points from the count.

// answers the question: "Would a grid be within character's line of sight,

// Answers the question: "Would a grid be within character's line of sight,

// Usually calculates whether from one grid someone could see the other.
// Depending on the viewer's habitat, 'allowed' can be set to DNGN_FLOOR,
// DNGN_SHALLOW_WATER or DNGN_DEEP_WATER.
// Yes, this ignores lava-loving monsters.
bool grid_see_grid(int posx_1, int posy_1, int posx_2, int posy_2,
                   dungeon_feature_type allowed)
{
    if (distance(posx_1, posy_1, posx_2, posy_2) > LOS_RADIUS * LOS_RADIUS)
        return (false);
    dungeon_feature_type max_disallowed = DNGN_MAXOPAQUE;
    if (allowed != DNGN_UNSEEN)
        max_disallowed = static_cast<dungeon_feature_type>(allowed - 1);
    // XXX: Ignoring clouds for now.
    return (num_feats_between(posx_1, posy_1, posx_2, posy_2, DNGN_UNSEEN,
                              max_disallowed) == 0);
}

static bool _choose_random_target_grid_in_los(monsters *mon)

static bool _choose_random_patrol_target_grid(monsters *mon)

    int patrol_x = mon->patrol_point.x;
    int patrol_y = mon->patrol_point.y;
    dungeon_feature_type habitat = habitat2grid(
                                       mons_habitat_by_type(mon->type) );

            if (j == 0 && k == 0)
                continue;
            pos_x = mon->x + j;
            pos_y = mon->y + k;

            pos_x = patrol_x + j;
            pos_y = patrol_y + k;

            if (!mon->mon_see_grid(pos_x, pos_y))

            if (pos_x == mon->x && pos_y == mon->y)

            if (grid_see_grid(mon->x, mon->y, patrol_x, patrol_y, habitat))
            {
                // If the patrol point can be easily (within LOS) reached
                // from the current position, it suffices if the target is
                // within reach of the patrol point OR the current position:
                // we can easily get there.
                if (!grid_see_grid(patrol_x, patrol_y, pos_x, pos_y, habitat)
                    && !grid_see_grid(mon->x, mon->y, pos_x, pos_y, habitat))
                {
                    continue;
                }
            }
            else
            {
                // If, however, the patrol point is out of reach, we have to
                // make sure the new target brings us into reach of it.
                // This means that the target must be reachable BOTH from
                // the patrol point AND the current position.
                if (!grid_see_grid(patrol_x, patrol_y, pos_x, pos_y, habitat)
                    || !grid_see_grid(mon->x, mon->y, pos_x, pos_y, habitat))
                {
                    continue;
                }
            }

                    if (mon->patrol_point != coord_def(mon->x, mon->y)
                        || !_choose_random_target_grid_in_los(mon))

                    if (!_choose_random_patrol_target_grid(mon))

                        // If we couldn't find a target that is within easy
                        // reach of the monster and close to the patrol point,
                        // it's time to head back.

// note that this function *completely* blocks messaging for monsters

// Note that this function *completely* blocks messaging for monsters

        // notice how few cases are actually accounted for here {dlb}:

        // Notice how few cases are actually accounted for here {dlb}:

                // this break causes the wand to be tried on the player:

                // This break causes the wand to be tried on the player.

        // fire tracer, if necessary

        // Fire tracer, if necessary.

    // ok, we'll try it.

    // Ok, we'll try it.

    // set fake damage for the tracer.

    // Set fake damage for the tracer.

    // clear fake damage (will be set correctly in mons_throw).

    // Clear fake damage (will be set correctly in mons_throw).

    // monster just summoned (or just took stairs), skip this action

    // Monster just summoned (or just took stairs), skip this action.

    // Handle clouds on nonmoving monsters:

    // Handle clouds on nonmoving monsters.

            // clear list of beholding monsters

            // Clear list of beholding monsters.

// Returns false if monster doesn't spend any time pickup up

// Returns false if monster doesn't spend any time picking something up.

    // Batty monsters are unpushable

    // Batty monsters are unpushable.

// returns true for monsters that obviously (to the player) feel
// "thematically at home" in a branch
// currently used for native monsters recognizing traps

// Returns true for monsters that obviously (to the player)
// feel "thematically at home" in a branch.
// Currently used for native monsters recognizing traps.

    // friendlies will try not to be parted from you

    // Friendlies will try not to be parted from you.

        && monster->foe != MHITNOT

        && (monster->foe != MHITNOT || monster->is_patrolling())

    // wandering through a trap is OK if we're pretty healthy,
    // really stupid, or immune to the trap

    // Wandering through a trap is OK if we're pretty healthy,
    // really stupid, or immune to the trap.

    {

    }

            // this isn't harmful, but dumb critters might think so.

            // This isn't harmful, but dumb critters might think so.

        // if we get here, the cloud is potentially harmful.
        // exceedingly dumb creatures will still wander in.

        // If we get here, the cloud is potentially harmful.
        // Exceedingly dumb creatures will still wander in.

    // if we end up here the monster can safely move

    // If we end up here the monster can safely move.

    // Berserking monsters make a lot of racket

    // Berserking monsters make a lot of racket.

    // let's not even bother with this if mmov_x and mmov_y are zero.

    // Let's not even bother with this if mmov_x and mmov_y are zero.

             // [ds] Bounds check was after grd[targ_x][targ_y] which would
             // trigger an ASSERT. Moved it up.

             // bounds check - don't consider moving out of grid!

             // Bounds check - don't consider moving out of grid!

        } // now we know where we _can_ move.

        }
    // Now we know where we _can_ move.

    // normal/smart monsters know about secret doors (they _live_ in the
    // dungeon!)

    // Normal/smart monsters know about secret doors
    // (they _live_ in the dungeon!)

            // for zombies, monster type is kept in mon->base_monster

            // For zombies, monster type is kept in mon->base_monster.

    // water creatures have a preference for water they can hide in -- bwr

    // Water creatures have a preference for water they can hide in -- bwr

            // which one was better? -- depends on FLEEING or not

            // Which one was better? -- depends on FLEEING or not.

    // if we haven't found a good move by this point, we're not going to.

    // If we haven't found a good move by this point, we're not going to.

    // take care of beetle burrowing

    // Take care of beetle burrowing.

        // check for attacking player

        // Check for attacking player.

        // check for attacking another monster

        // Check for attacking another monster.

        // fleeing monsters that can't move will panic and possibly
        // turn to face their attacker

        // Fleeing monsters that can't move will panic and possibly
        // turn to face their attacker.

    // First time we've seen this particular monster

    // First time we've seen this particular monster.

        // try and find a random floor space some distance away

        // Try and find a random floor space some distance away.

            // don't drop on anything but vanilla floor right now

            // Don't drop on anything but vanilla floor right now.

        mg.proximity =
            (one_chance_in(10) ? PROX_NEAR_STAIRS : PROX_AWAY_FROM_PLAYER);

        mg.proximity = (one_chance_in(10) ? PROX_NEAR_STAIRS
                                          : PROX_AWAY_FROM_PLAYER);

    // all monsters have been assigned? {dlb}

    // All monsters have been assigned? {dlb}

    // this gives a slight challenge to the player as they ascend the
    // dungeon with the Orb

    // This gives a slight challenge to the player as they ascend the
    // dungeon with the Orb.

    // look at special cases: CHARMED, FRIENDLY, HOSTILE, GOD_GIFT
    // alert summoned being to player's presence

    // Look at special cases: CHARMED, FRIENDLY, HOSTILE, GOD_GIFT.
    // Alert summoned being to player's presence.

    if (mg.needs_patrol_point())
        creation->patrol_point = coord_def(creation->x, creation->y);

        if (is_patrolling())
        {
            // Enslaved monsters stop patrolling and forget their patrol point,
            // they're supposed to follow you now.
            patrol_point = coord_def(0, 0);
        }

        if (is_patrolling())
        {
            // Enslaved monsters stop patrolling and forget their patrol point,
            // in case they were on order to wait.
            patrol_point = coord_def(0, 0);
        }

                       "a      : acquirement\n"
                       "A      : set all skills to level\n"
                       "Ctrl-A : generate new Abyss area\n"
                       "b      : controlled blink\n"
                       "B      : banish yourself to the Abyss\n"
                       "c      : card effect\n"
                       "C      : (un)curse item\n"
                       "g      : add a skill\n"
                       "G      : banish all monsters\n"
                       "Ctrl-G : save ghost (bones file)\n"
                       "f      : player combat damage stats\n"
                       "F      : combat stats with fsim_kit\n"
                       "Ctrl-F : combat stats (monster vs PC)\n"
                       "h/H    : heal yourself (super-Heal)\n"
                       "i/I    : identify/unidentify inventory\n"
                       "Ctrl-I : item generation stats\n"
                       "l      : make entrance to labyrinth\n"
                       "L      : place a vault by name\n"
                       "m/M    : create monster by number/name\n"
                       "o/%    : create an object\n"
                       "p      : make entrance to pandemonium\n"
                       "P      : make a portal (i.e., bazaars)\n"
                       "r      : change character's species\n"
                       "s      : gain 20000 skill points\n"
                       "S      : set skill to level\n",

                       "<w>a</w>      : acquirement\n"
                       "<w>A</w>      : set all skills to level\n"
                       "<w>Ctrl-A</w> : generate new Abyss area\n"
                       "<w>b</w>      : controlled blink\n"
                       "<w>B</w>      : banish yourself to the Abyss\n"
                       "<w>c</w>      : card effect\n"
                       "<w>C</w>      : (un)curse item\n"
                       "<w>g</w>      : add a skill\n"
                       "<w>G</w>      : banish all monsters\n"
                       "<w>Ctrl-G</w> : save ghost (bones file)\n"
                       "<w>f</w>      : player combat damage stats\n"
                       "<w>F</w>      : combat stats with fsim_kit\n"
                       "<w>Ctrl-F</w> : combat stats (monster vs PC)\n"
                       "<w>h</w>/<w>H</w>    : heal yourself (super-Heal)\n"
                       "<w>i</w>/<w>I</w>    : identify/unidentify inventory\n"
                       "<w>Ctrl-I</w> : item generation stats\n"
                       "<w>l</w>      : make entrance to labyrinth\n"
                       "<w>L</w>      : place a vault by name\n"
                       "<w>m</w>/<w>M</w>    : create monster by number/name\n"
                       "<w>o</w>/<w>%</w>    : create an object\n"
                       "<w>p</w>      : make entrance to pandemonium\n"
                       "<w>P</w>      : make a portal (i.e., bazaars)\n"
                       "<w>r</w>      : change character's species\n"
                       "<w>s</w>      : gain 20000 skill points\n"
                       "<w>S</w>      : set skill to level\n",

                       "t      : tweak object properties\n"
                       "T      : make a trap\n"
                       "v      : show gold value of an item\n"
                       "x      : gain an experience level\n"
                       "Ctrl-X : change experience level\n"
                       "X      : make Xom do something now\n"
                       "z/Z    : cast spell by number/name\n"
                       "$      : get 1000 gold\n"
                       "</>    : create up/down staircase\n"
                       "u/d    : shift up/down one level\n"
                       "~      : go to a specific level\n"
                       "(/)    : make feature by number/name\n"
                       "]      : get a mutation\n"
                       "[      : get a demonspawn mutation\n"
                       ":      : find branches in the dungeon\n"
                       "{      : magic mapping\n"
                       "^      : gain piety\n"
                       "_      : gain religion\n"
                       "'      : list items\n"
                       "\"      : list monsters\n"
                       "?      : list wizard commands\n"
                       "|      : make unrand/fixed artefacts\n"
                       "+      : make randart from item\n"
                       "@      : set Str Int Dex\n"
                       "\\      : make a shop\n",

                       "<w>t</w>      : tweak object properties\n"
                       "<w>T</w>      : make a trap\n"
                       "<w>v</w>      : show gold value of an item\n"
                       "<w>x</w>      : gain an experience level\n"
                       "<w>Ctrl-X</w> : change experience level\n"
                       "<w>X</w>      : make Xom do something now\n"
                       "<w>z</w>/<w>Z</w>    : cast spell by number/name\n"
                       "<w>$</w>      : get 1000 gold\n"
                       "<w><<</w>/<w>></w>    : create up/down staircase\n"
                       "<w>u</w>/<w>d</w>    : shift up/down one level\n"
                       "<w>~</w>      : go to a specific level\n"
                       "<w>(</w>/<w>)</w>    : make feature by number/name\n"
                       "<w>]</w>      : get a mutation\n"
                       "<w>[</w>      : get a demonspawn mutation\n"
                       "<w>:</w>      : find branches in the dungeon\n"
                       "<w>{</w>      : magic mapping\n"
                       "<w>^</w>      : gain piety\n"
                       "<w>_</w>      : gain religion\n"
                       "<w>'</w>      : list items\n"
                       "<w>\"</w>      : list monsters\n"
                       "<w>?</w>      : list wizard commands\n"
                       "<w>|</w>      : create all unrand/fixed artefacts\n"
                       "<w>+</w>      : make randart from item\n"
                       "<w>@</w>      : set Str Int Dex\n"
                       "<w>\\</w>      : make a shop\n",