Centralized "fish can't attack non-swimmer" logic.

apps/openmw/mwmechanics/actors.cpp

@@ -37,6 +37,7 @@
 
 #include "actor.hpp"
 #include "summoning.hpp"
+#include "combat.hpp"
 
 namespace
 {
@@ -309,10 +310,10 @@ namespace MWMechanics
         // pure water creatures won't try to fight with the target on the ground
         // except that creature is already hostile
         if ((againstPlayer || !creatureStats.getAiSequence().isInCombat())
-                && ((actor1.getClass().isPureWaterCreature(actor1)
-                && !MWBase::Environment::get().getWorld()->isWading(actor2))
-                || (!actor1.getClass().canSwim(actor1) && MWBase::Environment::get().getWorld()->isSwimming(actor2)))) // creature can't swim to target
+            && !MWMechanics::isEnvironmentCompatible(actor1, actor2)) // creature can't swim to target
+        {
             return;
+        }
 
         bool aggressive;
 

apps/openmw/mwmechanics/aicombat.cpp

@@ -23,6 +23,7 @@
 #include "character.hpp" // fixme: for getActiveWeapon
 
 #include "aicombataction.hpp"
+#include "combat.hpp"
 
 namespace
 {
@@ -206,12 +207,8 @@ namespace MWMechanics
         const MWWorld::Class& actorClass = actor.getClass();
         MWBase::World* world = MWBase::Environment::get().getWorld();
 
-        if (!actorClass.isNpc() &&
-            // 1. pure water creature and Player moved out of water
-            ((target == world->getPlayerPtr() &&
-            actorClass.isPureWaterCreature(actor) && !world->isWading(target))
-            // 2. creature can't swim to target
-            || (!actorClass.canSwim(actor) && world->isSwimming(target))))
+        // can't fight if attacker can't go where target is.  E.g. A fish can't attack person on land.
+        if (!actorClass.isNpc() && !MWMechanics::isEnvironmentCompatible(actor, target))
         {
             actorClass.getCreatureStats(actor).setAttackingOrSpell(false);
             return true;

apps/openmw/mwmechanics/combat.cpp

@@ -367,4 +367,24 @@ namespace MWMechanics
         else
             sndMgr->playSound3D(victim, "Hand To Hand Hit", 1.0f, 1.0f);
     }
+
+    bool isEnvironmentCompatible(const MWWorld::Ptr& attacker, const MWWorld::Ptr& victim)
+    {
+        const MWWorld::Class& attackerClass = attacker.getClass();
+        MWBase::World* world = MWBase::Environment::get().getWorld();
+
+        // If attacker is fish, victim must be in water
+        if (attackerClass.isPureWaterCreature(attacker))
+        {
+            return world->isWading(victim);
+        }
+        
+        // If attacker can't swim, victim must not be in water
+        if (!attackerClass.canSwim(attacker))
+        {
+            return !world->isSwimming(victim);
+        }
+
+        return true;
+    }
 }

apps/openmw/mwmechanics/combat.hpp

@@ -34,6 +34,10 @@ void adjustWeaponDamage (float& damage, const MWWorld::Ptr& weapon);
 
 void getHandToHandDamage (const MWWorld::Ptr& attacker, const MWWorld::Ptr& victim, float& damage, bool& healthdmg);
 
+/// Can attacker operate in victim's environment?
+/// e.g. If attacker is a fish, is victim in water? Or, if attacker can't swim, is victim on land?
+bool isEnvironmentCompatible(const MWWorld::Ptr& attacker, const MWWorld::Ptr& victim);
+
 }
 
 #endif