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diff --git a/Hard-Coded-Game-Logic.md b/Hard-Coded-Game-Logic.md new file mode 100644 index 0000000..7acad03 --- /dev/null +++ b/Hard-Coded-Game-Logic.md @@ -0,0 +1,98 @@ +# Hard-Coded Game Logic + +Much of the game logic can be changed via the files in [data/](../blob/master/data/), but some things are hard-coded and can be tricky to find. This page lists things that may trip you up when hacking. + + +## `RIVAL1`'s first Pokémon has no held item + +This is caused by `InitEnemyTrainer` in [engine/battle/core.asm](../blob/master/engine/battle/core.asm): + +```asm + ; RIVAL1's first mon has no held item + ld a, [TrainerClass] + cp RIVAL1 + jr nz, .ok + xor a + ld [OTPartyMon1Item], a +.ok +``` + + +## `RIVAL1` and `RIVAL2` don't print their trainer class in battle + +Both of these classes are named "RIVAL", but battles just print "SILVER wants to battle!", not "RIVAL SILVER wants to battle!" + +This is caused by `PlaceEnemysName` in [home/text.asm](../blob/master/home/text.asm): + +```asm + ld a, [TrainerClass] + cp RIVAL1 + jr z, .rival + cp RIVAL2 + jr z, .rival +``` + + +## Some trainer classes have different battle music + +This is caused by `PlayBattleMusic` in [engine/battle/start_battle.asm](../blob/master/engine/battle/start_battle.asm). The routine's logic is: + +- If `[BattleType]` is `BATTLETYPE_SUICUNE` or `BATTLETYPE_ROAMING`, play `MUSIC_SUICUNE_BATTLE`. +- If it's a wild battle, play `MUSIC_KANTO_WILD_BATTLE` if we're in Kanto, `MUSIC_JOHTO_WILD_BATTLE_NIGHT` in Johto at night, or `MUSIC_JOHTO_WILD_BATTLE` during morning and day. +- If `[OtherTrainerClass]` is `CHAMPION` or `RED`, play `MUSIC_CHAMPION_BATTLE`. +- If `[OtherTrainerClass]` is `GRUNTM` or `GRUNTF`, play `MUSIC_ROCKET_BATTLE`. (They should have included `EXECUTIVEM`, `EXECUTIVEF`, and `SCIENTIST` too…) +- If `[OtherTrainerClass]` is listed under `KantoGymLeaders` in [data/trainers/leaders.asm](../blob/master/data/trainers/leaders.asm), play `MUSIC_KANTO_GYM_LEADER_BATTLE`. +- If `[OtherTrainerClass]` is listed under `GymLeaders` in [data/trainers/leaders.asm](../blob/master/data/trainers/leaders.asm), play `MUSIC_JOHTO_GYM_LEADER_BATTLE`. (`CHAMPION`, `RED`, and the Kanto Gym leaders are listed but have already been accounted for at this point.) +- If `[OtherTrainerClass]` is `RIVAL2` and `[OtherTrainerID]` is at least `RIVAL2_2_CHIKORITA` (i.e. we're battling our rival in Indigo Plateau), play `MUSIC_CHAMPION_BATTLE`. +- If `[OtherTrainerClass]` is `RIVAL1` or `RIVAL2`, play `MUSIC_RIVAL_BATTLE`. +- If it's a link battle, play `MUSIC_JOHTO_TRAINER_BATTLE`. +- Play `MUSIC_KANTO_TRAINER_BATTLE` if we're in Kanto or `MUSIC_JOHTO_TRAINER_BATTLE` if we're in Johto. + + +## Some maps don't display a location sign + +This is caused by `ReturnFromMapSetupScript.CheckSpecialMap` in [engine/events/map_name_sign.asm](../blob/master/engine/events/map_name_sign.asm): + +```asm +.CheckSpecialMap: ; b8070 +; These landmarks do not get pop-up signs. + cp -1 + ret z + cp SPECIAL_MAP + ret z + cp RADIO_TOWER + ret z + cp LAV_RADIO_TOWER + ret z + cp UNDERGROUND_PATH + ret z + cp INDIGO_PLATEAU + ret z + cp POWER_PLANT + ret z + ld a, $1 + and a + ret +; b8089 +``` + + +## Outdoor maps within indoor maps don't confuse Dig or Escape Rope + +Dig and Escape Rope take you out of a dungeon and back to the entrance you used. However, some dungeons are designed with an enclosed outdoor portion, and it would be bad if visiting those portions made Dig or Escape Rope take you back to *them* instead of properly outside the dungeon. + +There's no "outdoor-within-indoor" map environment, so the few maps in this situation have to be hard-coded. It's caused by `LoadWarpData.SaveDigWarp` in [engine/warp_connection.asm](../blob/master/engine/warp_connection.asm): + +```asm +; MOUNT_MOON_SQUARE and TIN_TOWER_ROOF are outdoor maps within indoor maps. +; Dig and Escape Rope should not take you to them. + ld a, [wPrevMapGroup] + cp GROUP_MOUNT_MOON_SQUARE ; GROUP_TIN_TOWER_ROOF + jr nz, .not_mt_moon_or_tin_tower + ld a, [wPrevMapNumber] + cp MAP_MOUNT_MOON_SQUARE + ret z + cp MAP_TIN_TOWER_ROOF + ret z +.not_mt_moon_or_tin_tower +``` |