Use half extents for destination distance tolerance in AiEscort

For actors moving in water destination may be located at such z coordinate
that they can't reach.

apps/openmw/mwmechanics/aiescort.cpp

@@ -73,25 +73,25 @@ namespace MWMechanics
         const MWWorld::Ptr follower = MWBase::Environment::get().getWorld()->getPtr(mTargetActorRefId, false);
         const osg::Vec3f leaderPos = actor.getRefData().getPosition().asVec3();
         const osg::Vec3f followerPos = follower.getRefData().getPosition().asVec3();
+        const osg::Vec3f halfExtents = MWBase::Environment::get().getWorld()->getHalfExtents(actor);
+        const float maxHalfExtent = std::max(halfExtents.x(), std::max(halfExtents.y(), halfExtents.z()));
 
         if ((leaderPos - followerPos).length2() <= mMaxDist * mMaxDist)
         {
             const osg::Vec3f dest(mX, mY, mZ);
-            if (pathTo(actor, dest, duration)) //Returns true on path complete
+            if (pathTo(actor, dest, duration, maxHalfExtent)) //Returns true on path complete
             {
                 mRemainingDuration = mDuration;
                 return true;
             }
-            const osg::Vec3f halfExtents = MWBase::Environment::get().getWorld()->getHalfExtents(actor);
-            mMaxDist = std::max(halfExtents.x(), std::max(halfExtents.y(), halfExtents.z())) + 450.0f;
+            mMaxDist = maxHalfExtent + 450.0f;
         }
         else
         {
             // Stop moving if the player is too far away
             MWBase::Environment::get().getMechanicsManager()->playAnimationGroup(actor, "idle3", 0, 1);
             actor.getClass().getMovementSettings(actor).mPosition[1] = 0;
-            const osg::Vec3f halfExtents = MWBase::Environment::get().getWorld()->getHalfExtents(actor);
-            mMaxDist = std::max(halfExtents.x(), std::max(halfExtents.y(), halfExtents.z())) + 250.0f;
+            mMaxDist = maxHalfExtent + 250.0f;
         }
 
         return false;