Battle config option for knockback style when on same tile.

conf/battle/battle.conf

@@ -142,3 +142,7 @@ arrow_decrement: 1
 // range. For example, Sonic Blow requires a 2 cell distance before autocasting is allowed.
 // This setting also affects autospellwhenhit.
 autospell_check_range: no
+
+// If both the attacker and the target are on the same tile, should the target be knocked back to the left?
+// Official behavior is "yes", setting this to "no" will knock the target back behind the attacker.
+knockback_left: yes

src/map/battle.c

@@ -6714,6 +6714,7 @@ static const struct battle_data {
 	{ "invincible.nodamage",                &battle_config.invincible_nodamage,             0,      0,      1,              },
 	{ "mob_slave_keep_target",              &battle_config.mob_slave_keep_target,           0,      0,      1,              },
 	{ "autospell_check_range",              &battle_config.autospell_check_range,           0,      0,      1,              },
+	{ "knockback_left",						&battle_config.knockback_left,					1,      0,      1,              },
 	{ "client_reshuffle_dice",              &battle_config.client_reshuffle_dice,           0,      0,      1,              },
 	{ "client_sort_storage",                &battle_config.client_sort_storage,             0,      0,      1,              },
 	{ "feature.buying_store",               &battle_config.feature_buying_store,            1,      0,      1,              },

src/map/battle.h

@@ -416,6 +416,7 @@ struct Battle_Config {
 	int invincible_nodamage;
 	int mob_slave_keep_target;
 	int autospell_check_range;	//Enable range check for autospell bonus. [L0ne_W0lf]
+	int knockback_left;
 	int client_reshuffle_dice;  // Reshuffle /dice
 	int client_sort_storage;
 	int feature_buying_store;

src/map/map.c

@@ -2413,9 +2413,10 @@ uint8 map_calc_dir(struct block_list* src, int16 x, int16 y)
 	dx = x-src->x;
 	dy = y-src->y;
 	if( dx == 0 && dy == 0 )
-	{	// both are standing on the same spot
-		dir = 6; // aegis-style, makes knockback default to the left
-		//dir = unit->getdir(src); // athena-style, makes knockback default to behind 'src'
+	{	// both are standing on the same spot.
+		// aegis-style, makes knockback default to the left.
+		// athena-style, makes knockback default to behind 'src'.
+		dir = (battle_config.knockback_left ? 6 : unit->getdir(src));
 	}
 	else if( dx >= 0 && dy >=0 )
 	{	// upper-right