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, 18 insertions, 2 deletions

diff --git a/src/map/unit.c b/src/map/unit.c
index f823a3fed..2d8fd530d 100644
--- a/src/map/unit.c
+++ b/src/map/unit.c
@@ -250,6 +250,19 @@ int unit_walktoxy_timer(int tid, int64 tick, int id, intptr_t data) {
 	if(map->getcell(bl->m,x+dx,y+dy,CELL_CHKNOPASS))
 		return unit->walktoxy_sub(bl);
 
+	//Monsters can only leave icewalls to the west and south
+	//But if movement fails more than icewall_walk_block times, they can ignore this rule
+	if(md && md->walktoxy_fail_count < battle_config.icewall_walk_block && map->getcell(bl->m,x,y,CELL_CHKICEWALL) && (dx > 0 || dy > 0)) {
+		//Needs to be done here so that rudeattack skills are invoked
+		md->walktoxy_fail_count++;
+		clif->fixpos(bl);
+		mob->unlocktarget(md, tick);
+		//Use idle skill at this point
+		if (!(++ud->walk_count%WALK_SKILL_INTERVAL))
+			mob->skill_use(md, tick, -1);
+		return 0;
+	}
+
 	//Refresh view for all those we lose sight
 	map->foreachinmovearea(clif->outsight, bl, AREA_SIZE, dx, dy, sd?BL_ALL:BL_PC, bl);
 
@@ -300,6 +313,8 @@ int unit_walktoxy_timer(int tid, int64 tick, int id, intptr_t data) {
 				sd->hd->masterteleport_timer = 0;
 		}
 	} else if (md) {
+		//Movement was successful, reset walktoxy_fail_count
+		md->walktoxy_fail_count = 0;
 		if( map->getcell(bl->m,x,y,CELL_CHKNPC) ) {
 			if( npc->touch_areanpc2(md) ) return 0; // Warped
 		} else
@@ -2010,8 +2025,9 @@ int unit_attack_timer_sub(struct block_list* src, int tid, int64 tick) {
 	sstatus = status->get_status_data(src);
 	range = sstatus->rhw.range;
 
-	if( unit->is_walking(target) )
-		range++; //Extra range when chasing
+	if( unit->is_walking(target) && (target->type == BL_PC || !map->getcell(target->m,target->x,target->y,CELL_CHKICEWALL)) )
+		range++; // Extra range when chasing (does not apply to mobs locked in an icewall)
+
 	if(sd && !check_distance_client_bl(src,target,range)) {
 		// Player tries to attack but target is too far, notify client
 		clif->movetoattack(sd,target);