Fix bug:7454

* Official Icewall implementation and other fixes
- Reverted all the icewall-related changes done in SVN r15777 and following as testing shows they aren't official and are actually pretty exploitable (bugreport:7412)
- Instead implemented the official icewall characteristic that monsters can only leave an icewall cell to the west or south, the changes include:
  * The "sight" path check no longer checks for the current cell so standing on an icewall allows you to see/attack into any direction
  * The path finding will still ignore the current cell as before but the walk routine will not allow to walk east or north while standing on an icewall cell
  * This leads monsters in the situation where they go through an AI loop not allowing them to escape the icewall (if their target is north or east of them)
  * Monster in this situation will use idle skills and if they get attacked will use their rudeattacked skills if available, similar to traps like Spiderweb
  * Added a configuration icewall_walk_block that allows to configure how long a monster should go through the AI loop before the server allows it any movement, this "safety" system is official and seems to equal about 75 AI loops; if you want to disable the whole icewall system so that monsters don't get stuck in icewall at all, just set this to 0
  * Here are videos from jRO showing how this system works: http://ragdo.blog56.fc2.com/blog-entry-763.html
- Implemented the official calculation for "direction"; now you will be considered horizontal/vertical/diagonally aligned with a target cell in the exact same way as on official servers, this is for example used to determine whether an icewall or a firewall should be horizontal, vertical or diagonal; the only thing that is still unofficial is the default direction (officially always "west"); effectively now there are more situations considered diagonal than before
- Further cleanups on the idle skill use code for immobile monsters and monsters near a player but without a target (now skill using will always go via mob_unlocktarget)
  * This also fixes that monsters switched to idle mode and start to use idle skills one second too late

Mega thanks to Playtester (rathena 5540d89cb0e)

1 files changed, 2 insertions, 1 deletions

diff --git a/src/map/battle.c b/src/map/battle.c
index 3b50d3507..6844d8bda 100644
--- a/src/map/battle.c
+++ b/src/map/battle.c
@@ -6830,7 +6830,8 @@ static const struct battle_data {
 	{ "guild_castle_expulsion",				&battle_config.guild_castle_expulsion,			0,		0,		1,				},
 	{ "song_timer_reset",                   &battle_config.song_timer_reset,                0,      0,      1,              },
 	{ "snap_dodge",                         &battle_config.snap_dodge,                      0,      0,      1,              },
-	{ "monster_chase_refresh",              &battle_config.mob_chase_refresh,               1,      0,      30,             }
+	{ "monster_chase_refresh",              &battle_config.mob_chase_refresh,               1,      0,      30,             },
+	{ "icewall_walk_block",                 &battle_config.icewall_walk_block,              75,     0,      255,            }
 };
 #ifndef STATS_OPT_OUT
 /**