Post: #4

this is a fix, not an issue

on really old sphere versions < 56b, the LOS check doesn't work correctly on diagonal positions, allowing the attacker get line of sight of the target traped inside the wall X. So there's no way to get line of sight to something on the other side of the wall, but sphere was incorrectly allowing the LOS

this bug got fixed on sphere 56b, making the LOS work correctly on diagonal checks, which will block the LOS to the char stuck inside the wall X

the same occur on fire field, because the char doesn't have LOS to the position inside the wall X, so it also can't cast spells targeting this blocked position

so maybe the only way to "unfix" this is enabling EF_NoDiagonalCheckLOS on sphere.ini to disable this diagonal checks, making sphere return the wrong result again. But honestly I highly don't recommend enable this setting, because disabling diagonal LOS checks will also bring many unwanted behaviors/exploits, like players using bow or casting spells through house walls, players killing NPCs on strategic locations between walls where the player can hit the NPC but the NPC can't hit the player, etc