From b0d56dff91a889eec27e9774abb19d9814aac565 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20Unneb=C3=A4ck?= <linus@folkdatorn.se>
Date: Sun, 3 Aug 2025 19:57:07 +0200
Subject: [PATCH] Document time of day bug in RandomUnseenWildMon (#1196)

---
 docs/bugs_and_glitches.md     | 44 +++++++++++++++++++++++++----------
 engine/overworld/wildmons.asm |  1 +
 2 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/docs/bugs_and_glitches.md b/docs/bugs_and_glitches.md
index 12947702d..ffb92b4e4 100644
--- a/docs/bugs_and_glitches.md
+++ b/docs/bugs_and_glitches.md
@@ -107,6 +107,7 @@ Fixes in the [multi-player battle engine](#multi-player-battle-engine) category
   - [`ScriptCall` can overflow `wScriptStack` and crash](#scriptcall-can-overflow-wscriptstack-and-crash)
   - [`LoadSpriteGFX` does not limit the capacity of `UsedSprites`](#loadspritegfx-does-not-limit-the-capacity-of-usedsprites)
   - [`ChooseWildEncounter` doesn't really validate the wild Pokémon species](#choosewildencounter-doesnt-really-validate-the-wild-pok%C3%A9mon-species)
+  - [`RandomUnseenWildMon` always picks a morning Pokémon species](#randomunseenwildmon-always-picks-a-morning-pok%C3%A9mon-species)
   - [`TryObjectEvent` arbitrary code execution](#tryobjectevent-arbitrary-code-execution)
   - [`ReadObjectEvents` overflows into `wObjectMasks`](#readobjectevents-overflows-into-wobjectmasks)
   - [`ClearWRAM` only clears WRAM bank 1](#clearwram-only-clears-wram-bank-1)
@@ -2222,6 +2223,18 @@ The exact cause of this bug is unknown.
 ```
 
 
+### `SFX_RUN` does not play correctly when a wild Pokémon flees from battle
+
+**Fix:** Edit `WildFled_EnemyFled_LinkBattleCanceled` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm):
+
+```diff
+-; BUG: SFX_RUN does not play correctly when a wild Pokemon flees from battle (see docs/bugs_and_glitches.md)
+  ld de, SFX_RUN
+- call PlaySFX
++ call WaitPlaySFX
+```
+
+
 ## Text
 
 
@@ -2677,6 +2690,25 @@ This allows Pokémon to be duplicated, among other effects. It does not have a s
 ```
 
 
+### `RandomUnseenWildMon` always picks a morning Pokémon species
+
+**Fix:** Edit `RandomUnseenWildMon` in [engine/overworld/wildmons.asm](https://github.com/pret/pokecrystal/blob/master/engine/overworld/wildmons.asm):
+
+```diff
+ .GetGrassmon:
+-; BUG: RandomUnseenWildMon always picks a morning Pokémon species (see docs/bugs_and_glitches.md)
++	ld a, [wTimeOfDay]
++	ld bc, NUM_GRASSMON * 2
++	call AddNTimes
+ 	push hl
+ 	ld bc, 5 + 4 * 2 ; Location of the level of the 5th wild Pokemon in that map
+ 	add hl, bc
+-	ld a, [wTimeOfDay]
+-	ld bc, NUM_GRASSMON * 2
+-	call AddNTimes
+```
+
+
 ### `TryObjectEvent` arbitrary code execution
 
 If `IsInArray` returns `nc`, data at `bc` will be executed as code.
@@ -2798,15 +2830,3 @@ This bug allows all the options to be updated at once if the left or right butto
  	ld a, [hl]
  	push af
 ```
-
-
-### `SFX_RUN` does not play correctly when a wild Pokémon flees from battle
-
-**Fix:** Edit `WildFled_EnemyFled_LinkBattleCanceled` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm):
-
-```diff
--; BUG: SFX_RUN does not play correctly when a wild Pokemon flees from battle (see docs/bugs_and_glitches.md)
- 	ld de, SFX_RUN
--	call PlaySFX
-+	call WaitPlaySFX
-```
diff --git a/engine/overworld/wildmons.asm b/engine/overworld/wildmons.asm
index 0e41bc14a..e36add328 100644
--- a/engine/overworld/wildmons.asm
+++ b/engine/overworld/wildmons.asm
@@ -781,6 +781,7 @@ RandomUnseenWildMon:
 	jr nc, .done
 
 .GetGrassmon:
+; BUG: RandomUnseenWildMon always picks a morning Pokémon species (see docs/bugs_and_glitches.md)
 	push hl
 	ld bc, 5 + 4 * 2 ; Location of the level of the 5th wild Pokemon in that map
 	add hl, bc