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Diffstat (limited to 'docs/bugs_and_glitches.md')
| -rw-r--r-- | docs/bugs_and_glitches.md | 116 |
1 files changed, 72 insertions, 44 deletions
diff --git a/docs/bugs_and_glitches.md b/docs/bugs_and_glitches.md index 69f902eb0..52d788987 100644 --- a/docs/bugs_and_glitches.md +++ b/docs/bugs_and_glitches.md @@ -1,11 +1,14 @@ # Bugs and Glitches +These are known bugs and glitches in the original Pokémon Crystal game: code that clearly does not work as intended, or that only works in limited circumstances but has the possibility to fail or crash. + ## Contents - [Thick Club and Light Ball can decrease damage done with boosted (Special) Attack](#thick-club-and-light-ball-can-decrease-damage-done-with-boosted-special-attack) - [Metal Powder can increase damage taken with boosted (Special) Defense](#metal-powder-can-increase-damage-taken-with-boosted-special-defense) - [Belly Drum sharply boosts Attack even with under 50% HP](#belly-drum-sharply-boosts-attack-even-with-under-50-hp) +- [Confusion damage is affected by type-boosting items and Explosion/Self-Destruct doubling](#confusion-damage-is-affected-by-type-boosting-items-and-explosionself-destruct-doubling) - [Moves that lower Defense can do so after breaking a Substitute](#moves-that-lower-defense-can-do-so-after-breaking-a-substitute) - [Counter and Mirror Coat still work if the opponent uses an item](#counter-and-mirror-coat-still-work-if-the-opponent-uses-an-item) - [A Disabled but PP Up–enhanced move may not trigger Struggle](#a-disabled-but-pp-upenhanced-move-may-not-trigger-struggle) @@ -27,6 +30,7 @@ - [Dragon Scale, not Dragon Fang, boosts Dragon-type moves](#dragon-scale-not-dragon-fang-boosts-dragon-type-moves) - [Daisy's grooming doesn't always increase happiness](#daisys-grooming-doesnt-always-increase-happiness) - [Magikarp in Lake of Rage are shorter, not longer](#magikarp-in-lake-of-rage-are-shorter-not-longer) +- [Magikarp length limits have a unit conversion error](#magikarp-length-limits-have-a-unit-conversion-error) - [Magikarp lengths can be miscalculated](#magikarp-lengths-can-be-miscalculated) - [Battle transitions fail to account for the enemy's level](#battle-transitions-fail-to-account-for-the-enemys-level) - [Slot machine payout sound effects cut each other off](#slot-machine-payout-sound-effects-cut-each-other-off) @@ -49,11 +53,12 @@ - [`TryObjectEvent` arbitrary code execution](#tryobjectevent-arbitrary-code-execution) - [`Special_CheckBugContestContestantFlag` can read beyond its data table](#special_checkbugcontestcontestantflag-can-read-beyond-its-data-table) - [`ClearWRAM` only clears WRAM bank 1](#clearwram-only-clears-wram-bank-1) -- [`GetForestTreeFrame` works, but it's still bad](#getforesttreeframe-works-but-its-still-bad) ## Thick Club and Light Ball can decrease damage done with boosted (Special) Attack +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + ([Video](https://www.youtube.com/watch?v=rGqu3d3pdok&t=450)) This is a bug with `SpeciesItemBoost` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm): @@ -88,6 +93,8 @@ This is a bug with `SpeciesItemBoost` in [engine/battle/effect_commands.asm](/en ## Metal Powder can increase damage taken with boosted (Special) Defense +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + ([Video](https://www.youtube.com/watch?v=rGqu3d3pdok&t=450)) This is a bug with `DittoMetalPowder` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm): @@ -144,6 +151,8 @@ This is a bug with `DittoMetalPowder` in [engine/battle/effect_commands.asm](/en ## Belly Drum sharply boosts Attack even with under 50% HP +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + ([Video](https://www.youtube.com/watch?v=zuCLMikWo4Y)) This is a bug with `BattleCommand_BellyDrum` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm): @@ -180,8 +189,19 @@ BattleCommand_BellyDrum: ; 37c1a ``` +## Confusion damage is affected by type-boosting items and Explosion/Self-Destruct doubling + +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + +([Video](https://twitter.com/crystal_rby/status/874626362287562752)) + +*To do:* Identify specific code causing this bug and fix it. + + ## Moves that lower Defense can do so after breaking a Substitute +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + ([Video](https://www.youtube.com/watch?v=OGwKPRJLaaI)) This bug affects Acid, Iron Tail, and Rock Smash. @@ -218,6 +238,8 @@ DefenseDownHit: ## Counter and Mirror Coat still work if the opponent uses an item +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + ([Video](https://www.youtube.com/watch?v=uRYyzKRatFk)) *To do:* Identify specific code causing this bug and fix it. @@ -225,6 +247,8 @@ DefenseDownHit: ## A Disabled but PP Up–enhanced move may not trigger Struggle +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + ([Video](https://www.youtube.com/watch?v=1v9x4SgMggs)) This is a bug with `CheckPlayerHasUsableMoves` in [engine/battle/core.asm](/engine/battle/core.asm): @@ -250,6 +274,8 @@ This is a bug with `CheckPlayerHasUsableMoves` in [engine/battle/core.asm](/engi ## A Pokémon that fainted from Pursuit will have its old status condition when revived +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + ([Video](https://www.youtube.com/watch?v=tiRvw-Nb2ME)) *To do:* Identify specific code causing this bug and fix it. @@ -257,6 +283,8 @@ This is a bug with `CheckPlayerHasUsableMoves` in [engine/battle/core.asm](/engi ## Lock-On and Mind Reader don't always bypass Fly and Dig +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + This bug affects Attract, Curse, Foresight, Mean Look, Mimic, Nightmare, Spider Web, Transform, and stat-lowering effects of moves like String Shot or Bubble during the semi-invulnerable turn of Fly or Dig. This is a bug with `CheckHiddenOpponent` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm): @@ -275,6 +303,8 @@ CheckHiddenOpponent: ; 37daa ## Beat Up can desynchronize link battles +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + ([Video](https://www.youtube.com/watch?v=202-iAsrIa8)) This is a bug with `BattleCommand_BeatUp` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm): @@ -310,6 +340,8 @@ This is a bug with `BattleCommand_BeatUp` in [engine/battle/effect_commands.asm] ## Present damage is incorrect in link battles +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + ([Video](https://www.youtube.com/watch?v=XJaQoKtrEuw)) This bug existed for all battles in Gold and Silver, and was only fixed for single-player battles in Crystal to preserve link compatibility. @@ -661,6 +693,8 @@ FastBallMultiplier: ## Dragon Scale, not Dragon Fang, boosts Dragon-type moves +*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.* + This is a bug with `ItemAttributes` in [items/attributes.asm](/items/attributes.asm): ```asm @@ -751,6 +785,43 @@ This is a bug with `LoadEnemyMon.CheckMagikarpArea` in [engine/battle/core.asm]( **Fix:** Change both `jr z, .Happiness` to `jr nz, .Happiness`. +## Magikarp length limits have a unit conversion error + +This is a bug with `LoadEnemyMon.CheckMagikarpArea` in [engine/battle/core.asm](/engine/battle/core.asm): + +```asm +; Get Magikarp's length + ld de, EnemyMonDVs + ld bc, PlayerID + callfar CalcMagikarpLength + +; No reason to keep going if length > 1536 (i.e. if length / 256 != 6) + ld a, [wMagikarpLength] + cp HIGH(1536) ; this compares to 6'0'', should be cp 5 + jr nz, .CheckMagikarpArea + +; 5% chance of skipping both size checks + call Random + cp 5 percent + jr c, .CheckMagikarpArea +; Try again if length > 1615 + ld a, [wMagikarpLength + 1] + cp LOW(1616) ; this compares to 6'80'', should be cp 3 + jr nc, .GenerateDVs + +; 20% chance of skipping this check + call Random + cp 20 percent - 1 + jr c, .CheckMagikarpArea +; Try again if length > 1599 + ld a, [wMagikarpLength + 1] + cp LOW(1600) ; this compares to 6'64'', should be cp 2 + jr nc, .GenerateDVs +``` + +**Fix:** Change the three `cp` instructions to use their commented values. + + ## Magikarp lengths can be miscalculated This is a bug with `CalcMagikarpLength.BCLessThanDE` in [engine/events/magikarp.asm](/engine/events/magikarp.asm): @@ -1410,46 +1481,3 @@ ClearWRAM:: ; 25a ``` **Fix:** Change `jr nc, .bank_loop` to `jr c, .bank_loop`. - - -## `GetForestTreeFrame` works, but it's still bad - -In [tilesets/animations.asm](/tilesets/animations.asm): - -```asm -GetForestTreeFrame: ; fc54c -; Return 0 if a is even, or 2 if odd. - and a - jr z, .even - cp 1 - jr z, .odd - cp 2 - jr z, .even - cp 3 - jr z, .odd - cp 4 - jr z, .even - cp 5 - jr z, .odd - cp 6 - jr z, .even -.odd - ld a, 2 - scf - ret -.even - xor a - ret -; fc56d -``` - -**Fix:** - -```asm -GetForestTreeFrame: ; fc54c -; Return 0 if a is even, or 2 if odd. - and 1 - add a - ret -; fc56d -``` |