Attempt to make monster attacks on submerged monsters consistent with

player attacks on the same (aside from tentacle attacks, which only
monsters can currently have and which work on all submerged monsters).

1 files changed, 20 insertions, 4 deletions

diff --git a/crawl-ref/source/monstuff.cc b/crawl-ref/source/monstuff.cc
index 9a2e180e1c..f528547519 100644
--- a/crawl-ref/source/monstuff.cc
+++ b/crawl-ref/source/monstuff.cc
@@ -2788,6 +2788,24 @@ bool swap_check(monsters *monster, coord_def &loc, bool quiet)
     return (swap);
 }
 
+// Given an adjacent monster, returns true if the monster can hit it
+// (the monster should not be submerged, be submerged in shallow water
+// if the monster has a polearm, or be submerged in anything if the
+// monster has tentacles).
+bool monster_can_hit_monster(monsters *monster, const monsters *targ)
+{
+    if (!mons_is_submerged(targ))
+        return (true);
+
+    if (grd(targ->pos()) == DNGN_SHALLOW_WATER)
+    {
+        item_def *weapon = monster->weapon();
+        return (weapon && weapon_skill(*weapon) == SK_POLEARMS);
+    }
+
+    return (monster->has_damage_type(DVORP_TENTACLE));
+}
+
 void mons_get_damage_level(const monsters* monster, std::string& desc,
                            mon_dam_level_type& dam_level)
 {
@@ -7802,13 +7820,11 @@ static void _handle_monster_move(monsters *monster)
             }
 
             // See if we move into (and fight) an unfriendly monster.
-            // FIXME: looks like the lack of a check on 'submerged' here
-            // is the reason monsters can attack submerged monsters they
-            // happen to walk into. -cao
             monsters* targ = monster_at(monster->pos() + mmov);
             if (targ
                 && targ != monster
-                && !mons_aligned(monster->mindex(), targ->mindex()))
+                && !mons_aligned(monster->mindex(), targ->mindex())
+                && monster_can_hit_monster(monster, targ))
             {
                 // Maybe they can swap places?
                 if (_swap_monsters(monster, targ))