### Compile and install libpng

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Uncompress, configure, and install the libpng library from source.

```bash
tar xf libpng-1.6.37.tar.xz
cd libpng-1.6.37
./configure --prefix=/usr
make check
make install
```

--------------------------------

### Example Script Using Flags

Source: https://github.com/pret/pokeemerald/wiki/The-Basics-of-Scripting

A complete script example demonstrating how to check, display messages, and set a system flag.

```gas
Script_CheckDexFlag::
	lock
	faceplayer
	goto_if_set FLAG_SYS_POKEDEX_GET, Script_DexFlagSet
	msgbox Text_DexFlagClear, MSGBOX_DEFAULT
	setflag FLAG_SYS_POKEDEX_GET
	release
	end
	
Script_DexFlagSet::
	msgbox Text_DexFlagSet, MSGBOX_DEFAULT
	release
	end
	
Text_DexFlagClear:
	.string "Pokédex flag is cleared.$"
	
Text_DexFlagSet:
	.string "Pokédex flag is set.$"
```

--------------------------------

### Install agbcc (Initial build)

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Commands to clone and build agbcc for the first time.

```bash
git clone https://github.com/pret/agbcc
cd agbcc
./build.sh
./install.sh ../pokeemerald
```

--------------------------------

### Install build dependencies

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Installs the essential tools and libraries required to compile the pokeemerald project.

```bash
sudo apt install build-essential binutils-arm-none-eabi git libpng-dev
```

--------------------------------

### Install agbcc (Existing build)

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Commands to install an already built agbcc into the project directory.

```bash
cd agbcc
./install.sh ../pokeemerald
```

--------------------------------

### Install Dependencies on OpenBSD

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Install required packages using pkg_add.

```bash
pkg_add gmake bash arm-none-eabi-binutils clang git
```

--------------------------------

### Usage Example for checkforspecies

Source: https://github.com/pret/pokeemerald/wiki/Useful-Scripting-Specials

Example script demonstrating how to use the checkforspecies macro.

```assembly
Route101_EventScript_RouteSign::
    checkforspecies SPECIES_TORCHIC, NO_PARTY_SCREEN, Route101_EventScript_RouteSign_HasTorchic
    msgbox Route101_EventScript_Text_NoTorchic, MSGBOX_DEFAULT
    release
    end

Route101_EventScript_RouteSign_HasTorchic::
    msgbox Route101_EventScript_Text_HasTorchic, MSGBOX_DEFAULT
    release
    end

Route101_EventScript_Text_NoTorchic:
    .string "You don't have a TORCHIC.$"

Route101_EventScript_Text_HasTorchic:
    .string "You have a TORCHIC!$"
```

--------------------------------

### Install devkitPro packages

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Commands to update the package database and install the required GBA development tools.

```bash
sudo pacman -Sy
sudo pacman -S gba-dev
```

--------------------------------

### Install Ubuntu WSL1

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Executes the installation of the Ubuntu distribution with WSL1 support enabled via PowerShell.

```powershell
wsl --install -d Ubuntu --enable-wsl1
```

--------------------------------

### Example Starter Pokémon Definitions

Source: https://github.com/pret/pokeemerald/wiki/New-Birch's-Briefcase-With-Fully-Custom-Starters-by-Archie-and-Mudskip

Examples of how to define starter Pokémon using the `MonChoiceData` structure. These constants can be renamed if the type trio changes, while retaining their ID values.

```C
[BALL_TOP_THIRD]        = {SPECIES_CHIKORITA, 5, GRASS_STARTER},
    [BALL_TOP_FOURTH]       = {SPECIES_TOTODILE, 5, WATER_STARTER},
    [BALL_MIDDLE_THIRD]     = {SPECIES_CYNDAQUIL, 5, FIRE_STARTER},
```

--------------------------------

### Start NixOS Development Shell

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Launch an interactive shell with the necessary build tools pre-configured.

```bash
nix-shell -p pkgsCross.arm-embedded.stdenv.cc git pkg-config libpng
```

--------------------------------

### Example Trainer Items

Source: https://github.com/pret/pokeemerald/wiki/How-to-create-a-new-regular-trainer-battle

This example shows how to define the items a trainer uses in battle, with a limit of four. Ensure that `ITEM_NONE` is used for any unused item slots.

```c
{ITEM_HYPER_POTION, ITEM_HYPER_POTION, ITEM_NONE, ITEM_NONE}
```

--------------------------------

### Install gdebi-core on WSL1

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Install the 'gdebi-core' package, which is required for installing devkitPro pacman. This command is for WSL1 environments.

```bash
sudo apt install gdebi-core
```

--------------------------------

### Usage Examples for moncryscript

Source: https://github.com/pret/pokeemerald/wiki/Supplementary-Scripting-Macros

Demonstrates how to invoke the macro and the resulting assembly code generated.

```assembly
	moncryscript SPECIES_MEOWTH, Text_SomeText
	@ separated for clarity
	release
	end
```

```assembly
	lock
	faceplayer
	waitse
	playmoncry SPECIES_MEOWTH, CRY_MODE_NORMAL
	bufferspeciesname 1, SPECIES_MEOWTH
	bufferstring 2, Text_SomeText
	msgbox Text_MonCryScript
	waitmoncry
	@ separated for clarity: below is not part of the command
	release
	end
```

--------------------------------

### Create and Implement a Task

Source: https://github.com/pret/pokeemerald/wiki/Overview∶-The-Game-Loop

Example of creating a task and a callback function that performs an action based on player input.

```c
// 5 is the priority, and is not important.
u8 taskId = CreateTask(ButtonPressSound_Task, 5);
...
void ButtonPressSound_Task(u8 taskId)
{
    if (gMain.newKeys & A_BUTTON)
    {
        PlaySE(SE_PC_LOGIN);
        if (++gTasks[taskId].data[0] == 10)
            DestroyTask(taskId);
    }
}
```

--------------------------------

### Install devkitARM on macOS

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Use dkp-pacman to install the GBA development toolchain and rules.

```bash
sudo dkp-pacman -Sy
sudo dkp-pacman -S gba-dev
sudo dkp-pacman -S devkitarm-rules
```

--------------------------------

### CONTROLLER_INTROSLIDE

Source: https://github.com/pret/pokeemerald/wiki/Battle-Controllers

The battle is starting, and the background art for this battle (depicting the terrain) should slide into view.

```APIDOC
## CONTROLLER_INTROSLIDE

### Description
The battle is starting, and the background art for this battle (depicting the terrain) should slide into view.

### Method
Inbound

### Endpoint
N/A

### Parameters
N/A

### Request Example
N/A

### Response
N/A
```

--------------------------------

### Usage Example of getobjectfacingdirection

Source: https://github.com/pret/pokeemerald/wiki/Useful-Scripting-Specials

Example script demonstrating how to use the macro to check the player's direction and trigger specific messages.

```asm
Route101_EventScript_RouteSign::
    getobjectfacingdirection OBJ_EVENT_ID_PLAYER, VAR_TEMP_1
    goto_if_eq VAR_TEMP_1, DIR_NORTH, Route101_EventScript_RouteSign_North
    goto_if_eq VAR_TEMP_1, DIR_SOUTH, Route101_EventScript_RouteSign_South
    goto_if_eq VAR_TEMP_1, DIR_WEST, Route101_EventScript_RouteSign_West
    goto_if_eq VAR_TEMP_1, DIR_EAST, Route101_EventScript_RouteSign_East
    end

Route101_EventScript_RouteSign_North:
    msgbox Route101_Text_RouteSign_North, MSGBOX_DEFAULT
    release
    end

Route101_EventScript_RouteSign_South:
    msgbox Route101_Text_RouteSign_South, MSGBOX_DEFAULT
    release
    end

Route101_EventScript_RouteSign_West:
    msgbox Route101_Text_RouteSign_West, MSGBOX_DEFAULT
    release
    end

Route101_EventScript_RouteSign_East:
    msgbox Route101_Text_RouteSign_East, MSGBOX_DEFAULT
    release
    end

Route101_Text_RouteSign_North:
    .string "The Player is facing North!$"

Route101_Text_RouteSign_South:
    .string "The Player is facing South!$"

Route101_Text_RouteSign_West:
    .string "The Player is facing West!$"

Route101_Text_RouteSign_East:
    .string "The Player is facing East!$"
```

--------------------------------

### Usage Example for List Menu Coloring

Source: https://github.com/pret/pokeemerald/wiki/List-Menu-Text-Coloring

Demonstrates how to assign specific colors to list menu items during initialization.

```c
for (i = 0; i < task->tNumItems; i++)
{
    sScrollableMultichoice_ListMenuItem[i].name = sScrollingMultichoiceLists[task->tScrollMultiId].list[i].name;
    sScrollableMultichoice_ListMenuItem[i].id = i;
    sScrollableMultichoice_ListMenuItem[i].colors[0] = TEXT_COLOR_RED; // all entries will have red text
}
```

--------------------------------

### Install gba-dev on Arch Linux

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Use pacman to install the required development packages for GBA projects.

```console
pacman -S gba-dev
```

--------------------------------

### Define Starting PC Items in pokeemerald

Source: https://github.com/pret/pokeemerald/wiki/Change-initial-PC-items

The sNewGamePCItems array in src/player_pc.c controls the items present in the PC at the start of a new game. Ensure the array ends with { ITEM_NONE, 0 } to terminate the list.

```c
static const u16 sNewGamePCItems[][2] =
{
    { ITEM_POTION, 1 },
    { ITEM_NONE, 0 }
};
```

```c
static const u16 sNewGamePCItems[][2] =
{
    { ITEM_POTION, 5 },
    { ITEM_LUCKY_EGG, 6},
    { ITEM_NONE, 0 }
};
```

--------------------------------

### Define Day and Night Start Times

Source: https://github.com/pret/pokeemerald/wiki/Change-Time-Based-Evolution-Times

Define these constants in `include/pokemon.h` to set the 24-hour start times for day and night. Customize these values as needed.

```c
#define DAY_START 4
#define NIGHT_START 18
```

--------------------------------

### Example Script for Item Giving

Source: https://github.com/pret/pokeemerald/wiki/Plural-Giveitem

This script demonstrates the usage of the 'giveitem' command with different quantities to test the pluralization functionality.

```asm
VerdanturfTown_EventScript_TownSign::
    giveitem ITEM_POTION, 2
    giveitem ITEM_ORAN_BERRY, 3
    giveitem ITEM_POKE_BALL, 1
    end
```

--------------------------------

### Usage Examples for emote

Source: https://github.com/pret/pokeemerald/wiki/Supplementary-Scripting-Macros

Demonstrates various emote calls and the resulting assembly output.

```assembly
	emote 3
	@ separated for clarity
	emote 1, EMOTE_HEART
	@ separated for clarity
	emote 2, EMOTE_QUESTION
```

```assembly
	playse SE_PIN
	applymovement 3, Common_Movement_ExclamationMark
	waitmovement 0
	applymovement 3, Common_Movement_Delay48
	waitmovement 0
	@ separated for clarity
	playse SE_PIN
	applymovement 1, Common_Movement_Heart
	waitmovement 0
	applymovement 1, Common_Movement_Delay48
	waitmovement 0
	@ separated for clarity
	playse SE_PIN
	applymovement 2, Common_Movement_QuestionMark
	waitmovement 0
	applymovement 2, Common_Movement_Delay48
	waitmovement 0
```

--------------------------------

### Install createpartymon branch

Source: https://github.com/pret/pokeemerald/wiki/Temporarily-Replace-Player-or-Enemy-Party-Pokemon

Commands to add the remote repository and pull the createpartymon branch into your local pokeemerald project.

```bash
git remote add petuh https://github.com/Petuuuhhh/pokeemerald
```

```bash
git pull petuh createpartymon
```

--------------------------------

### Include Headers for Item Use

Source: https://github.com/pret/pokeemerald/wiki/Add-Nuzlocke-Challenge

Adds necessary headers for battle setup and region map functionality in item_use.c.

```C
+#include "battle_setup.h"
+#include "region_map.h"
```

--------------------------------

### Install Debug System

Source: https://github.com/pret/pokeemerald/wiki/Add-a-debug-menu

Commands to add the remote repository, pull the debug branch, and rebuild the project with debugging enabled.

```c
git remote add xaman https://github.com/TheXaman/pokeemerald/
git pull xaman tx_debug_system
make clean
make debugging
```

--------------------------------

### Modify Battle Setup and Trainer Logic

Source: https://github.com/pret/pokeemerald/wiki/Allow-Running-From-Trainer-Battles

Updates to src/battle_setup.c to track the previous trainer and handle the run outcome flag.

```diff
------------------------------ src/battle_setup.c ------------------------------
index 03bc0a08e7..e17db26d14 100644
@@ -113,8 +113,9 @@ EWRAM_DATA static u8 *sTrainerBattleEndScript = NULL;
 EWRAM_DATA static u8 *sTrainerABattleScriptRetAddr = NULL;
 EWRAM_DATA static u8 *sTrainerBBattleScriptRetAddr = NULL;
 EWRAM_DATA static bool8 sShouldCheckTrainerBScript = FALSE;
 EWRAM_DATA static u8 sNoOfPossibleTrainerRetScripts = 0;
+EWRAM_DATA static u32 sPrevTrainerSeeing = 0;
 
 // The first transition is used if the enemy pokemon are lower level than our pokemon.
 // Otherwise, the second transition is used.
 static const u8 sBattleTransitionTable_Wild[][2] =
@@ -1271,9 +1272,13 @@ void SetUpTwoTrainersBattle(void)
 
 bool32 GetTrainerFlagFromScriptPointer(const u8 *data)
 {
     u32 flag = TrainerBattleLoadArg16(data + 2);
-    return FlagGet(TRAINER_FLAGS_START + flag);
+    bool8 trainerFlagValue = FlagGet(TRAINER_FLAGS_START + flag);
+    if (flag != sPrevTrainerSeeing && !trainerFlagValue){
+        sPrevTrainerSeeing = flag;
+        FlagClear(FLAG_RAN_FROM_TRAINER);
+    }
+    return (trainerFlagValue || FlagGet(FLAG_RAN_FROM_TRAINER));
 }
 
 // Set trainer's movement type so they stop and remain facing that direction
 // Note: Only for trainers who are spoken to directly
@@ -1412,10 +1422,16 @@ static void CB2_EndTrainerBattle(void)
     {
         SetMainCallback2(CB2_ReturnToFieldContinueScriptPlayMapMusic);
         if (!InBattlePyramid() && !InTrainerHillChallenge())
         {
-            RegisterTrainerInMatchCall();
-            SetBattledTrainersFlags();
+            if (gBattleOutcome == B_OUTCOME_RAN){
+                FlagSet(FLAG_RAN_FROM_TRAINER);
+            }
+            else
+            {
+                FlagClear(FLAG_RAN_FROM_TRAINER);
+                RegisterTrainerInMatchCall();
+                SetBattledTrainersFlags();
+            }
         }
     }
 }
```

--------------------------------

### Implement warp script with flag

Source: https://github.com/pret/pokeemerald/wiki/Remove-Warp-Fadescreen

Example script usage showing how to set the flag before a warp command to suppress the fade.

```asm
VerdanturfTown_EventScript_Camper::
	lock
	faceplayer
	msgbox sText_1, MSGBOX_AUTOCLOSE
	fadescreen FADE_TO_BLACK
	setflag FLAG_REMOVE_WARP_FADE
	msgbox sText_2, MSGBOX_AUTOCLOSE
	warp MAP_RUSTBORO_CITY, 0, 0, 0
	end
```

--------------------------------

### Install devkitARM on WSL1

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Commands to install devkitARM on WSL1 after installing 'gdebi-core'. This includes installing the devkitPro pacman package and the gba-dev package.

```bash
cd /mnt/c/Users/<user>/Downloads
```

```bash
sudo gdebi devkitpro-pacman.amd64.deb
```

```bash
sudo dkp-pacman -Sy
```

```bash
sudo dkp-pacman -S gba-dev
```

--------------------------------

### Install devkitARM on Debian/Ubuntu

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Commands to install devkitARM on Debian/Ubuntu systems. This involves installing the devkitPro pacman package and the gba-dev package.

```bash
sudo gdebi devkitpro-pacman.amd64.deb
```

```bash
sudo dkp-pacman -Sy
```

```bash
sudo dkp-pacman -S gba-dev
```

--------------------------------

### Build ROM on OpenBSD

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Navigate to the project directory and initiate the build process.

```bash
cd ../pokeemerald
gmake
```

--------------------------------

### Install libpng using Homebrew on macOS

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Installs the libpng library on macOS using the Homebrew package manager. Ensure Homebrew is installed first.

```bash
brew install libpng
```

--------------------------------

### Initialize Debug Main Menu

Source: https://github.com/pret/pokeemerald/wiki/Add-a-debug-menu

Sets up and displays the main debug menu by creating a window, initializing a list menu, and starting a task to handle user input.

```c
void Debug_ShowMainMenu(void) {
    struct ListMenuTemplate menuTemplate;
    u8 windowId;
    u8 menuTaskId;
    u8 inputTaskId;

    // create window
    HideMapNamePopUpWindow();
    LoadMessageBoxAndBorderGfx();
    windowId = AddWindow(&sDebugMenuWindowTemplate);
    DrawStdWindowFrame(windowId, FALSE);

    // create list menu
    menuTemplate = sDebugMenuListTemplate;
    menuTemplate.windowId = windowId;
    menuTaskId = ListMenuInit(&menuTemplate, 0, 0);

    // draw everything
    CopyWindowToVram(windowId, 3);

    // create input handler task
    inputTaskId = CreateTask(DebugTask_HandleMainMenuInput, 3);
    gTasks[inputTaskId].data[0] = menuTaskId;
    gTasks[inputTaskId].data[1] = windowId;
}
```

--------------------------------

### Initialize Windows

Source: https://github.com/pret/pokeemerald/wiki/How-Menus-Work-‐-Part-2

Initializes a set of windows from a template list. Ensure the list is terminated with DUMMY_WIN_TEMPLATE.

```c
bool16 InitWindows(const struct WindowTemplate *templates)
```

--------------------------------

### Install Dependencies on Arch Linux

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Install required packages using pacman.

```bash
pacman -S base-devel arm-none-eabi-binutils arm-none-eabi-newlib git libpng
```

--------------------------------

### InitBgsFromTemplates

Source: https://github.com/pret/pokeemerald/wiki/How-Menus-Work-‐-Part-2

Initializes background layers using a template list.

```APIDOC
## void InitBgsFromTemplates(u8 bgMode, const struct BgTemplate *templates, u8 numTemplates)

### Description
Uses a list of BgTemplate structures to set up the GBA's background layers.

### Parameters
- **bgMode** (u8) - Required - The background mode (use 0 for text mode).
- **templates** (const struct BgTemplate *) - Required - Pointer to the list of background templates.
- **numTemplates** (u8) - Required - The number of templates in the list.
```

--------------------------------

### Install build dependencies in msys2

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Install the necessary toolchain packages required to compile the project.

```bash
pacman -Sy msys2-keyring
pacman -S make gcc zlib-devel git
```

--------------------------------

### Navigate to base directory

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Change directory to the parent folder containing the project components.

```bash
cd ..
```

--------------------------------

### Compare ROM to Original

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Run this command to verify if your built ROM matches the original game's ROM. It will output 'OK' on success or 'FAILED' with a warning if there are differences.

```bash
make compare
```

--------------------------------

### Configure Animation Start Delay

Source: https://github.com/pret/pokeemerald/wiki/How-to-add-a-new-Pokémon-species

Sets the delay in frames between the Pokémon's appearance and the start of its animation.

```diff
+    [SPECIES_MEWTHREE - 1]   = 15,
```

--------------------------------

### Install Xcode Command Line Tools

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Installs the Xcode Command Line Tools on macOS, which are necessary for development. This command should be run in the Terminal.

```bash
xcode-select --install
```

--------------------------------

### Get macOS CPU Core Count

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

On macOS, use this command to get the number of CPU cores for parallel builds, as 'nproc' is not available.

```bash
sysctl -n hw.ncpu
```

--------------------------------

### Configure Trainer Data for Mugshot Transition

Source: https://github.com/pret/pokeemerald/wiki/Custom-Battle-Mugshots

To enable a mugshot transition for a trainer, add the `.hasCustomTransition = TRUE` and `.transition = B_TRANSITION_MUGSHOT` fields to their data structure in `src/data/trainers.h`.

```c
        .hasCustomTransition = TRUE,
        .transition = B_TRANSITION_MUGSHOT,
```

--------------------------------

### Install Build Dependencies (Bash)

Source: https://github.com/pret/pokeemerald/blob/master/docs/legacy_WSL1_INSTALL.md

Installs essential packages required for building Pokeemerald on a Debian-based Linux system like WSL1. Ensure you have internet connectivity.

```bash
sudo apt install build-essential git libpng-dev gdebi-core
```

--------------------------------

### Initialize Background Layers

Source: https://github.com/pret/pokeemerald/wiki/How-Menus-Work-‐-Part-2

Configures background layers using a list of BgTemplate structures. Pass 0 for bgMode and use ARRAY_COUNT for the numTemplates argument.

```c
void InitBgsFromTemplates(u8 bgMode, const struct BgTemplate *templates, u8 numTemplates)
```

--------------------------------

### Initialize Save Version in NewGameInitData

Source: https://github.com/pret/pokeemerald/wiki/How-to-Support-Savefile-Backwards-Compatibility

Update the new game initialization logic in new_game.c to set the sentinel and version.

```diff
 void NewGameInitData(void)
 {
     if (gSaveFileStatus == SAVE_STATUS_EMPTY || gSaveFileStatus == SAVE_STATUS_CORRUPT)
         RtcReset();
 
     gDifferentSaveFile = TRUE;
+    gSaveBlock2Ptr->_saveSentinel = 0xFF;
+    gSaveBlock2Ptr->saveVersion = SAVE_VERSION;
     gSaveBlock2Ptr->encryptionKey = 0;
     ZeroPlayerPartyMons();
     ZeroEnemyPartyMons();
```

--------------------------------

### Change Battle Message for Snow/Hail

Source: https://github.com/pret/pokeemerald/wiki/Fix-Snow-Weather

Modify the gWeatherStartsStringIds array in src/battle_message.c to change the string displayed when snow starts, making it display 'Started Hail' instead.

```diff
const u16 gWeatherStartsStringIds[] =
{
    [WEATHER_NONE]               = STRINGID_ITISRAINING,
    [WEATHER_SUNNY_CLOUDS]       = STRINGID_ITISRAINING,
    [WEATHER_SUNNY]              = STRINGID_ITISRAINING,
    [WEATHER_RAIN]               = STRINGID_ITISRAINING,
-   [WEATHER_SNOW]               = STRINGID_ITISRAINING,
+   [WEATHER_SNOW]               = STRINGID_STARTEDHAIL,
    [WEATHER_RAIN_THUNDERSTORM]  = STRINGID_ITISRAINING,
    [WEATHER_FOG_HORIZONTAL]     = STRINGID_ITISRAINING,
    [WEATHER_VOLCANIC_ASH]       = STRINGID_ITISRAINING,
    [WEATHER_SANDSTORM]          = STRINGID_SANDSTORMISRAGING,
    [WEATHER_FOG_DIAGONAL]       = STRINGID_ITISRAINING,
    [WEATHER_UNDERWATER]         = STRINGID_ITISRAINING,
    [WEATHER_SHADE]              = STRINGID_ITISRAINING,
    [WEATHER_DROUGHT]            = STRINGID_SUNLIGHTSTRONG,
    [WEATHER_SNOW]               = STRINGID_STARTEDHAIL,
    [WEATHER_DOWNPOUR]           = STRINGID_ITISRAINING,
    [WEATHER_UNDERWATER_BUBBLES] = STRINGID_ITISRAINING,
    [WEATHER_ABNORMAL]           = STRINGID_ITISRAINING
};
```

--------------------------------

### Apply Movement Commands

Source: https://github.com/pret/pokeemerald/wiki/The-Basics-of-Scripting

Use applymovement to initiate a path for an object and waitmovement to ensure completion before proceeding.

```gas
applymovement [Local ID], [Movements Label]
waitmovement [Local ID=0]
```

```gas
Script_MovementsDemonstration::
	lock
	faceplayer
	msgbox Text_MovementsDemonstration, MSGBOX_DEFAULT
	applymovement 1, Movement_Example
	applymovement OBJ_EVENT_ID_PLAYER, Movement_Example
	waitmovement
	release
	end

Text_MovementsDemonstration:
	.string "Hey!\n"
	.string "Let's walk three steps up.$"

Movement_Example:
	walk_up
	walk_up
	walk_up
	step_end
```

--------------------------------

### Include Necessary Headers

Source: https://github.com/pret/pokeemerald/wiki/Trainer-Scripts

Ensure `src/script.c` includes `trainer_see.h` for access to `gApproachingTrainers` and `src/trainer_see.c` includes `event_scripts.h` for related definitions.

```c
#include "trainer_see.h"
```

```c
#include "event_scripts.h"
```

--------------------------------

### Example of Shared Data Space Structure

Source: https://github.com/pret/pokeemerald/wiki/Reuse-filler-save-space-for-Variables-and-Flags

This is an illustrative example showing how flags and variables share the same data space in gAdditionalSaveData. It highlights potential conflicts if IDs are not managed carefully.

```c
struct {
  u8 FLAG_FOR_SOMETHING_SUPER_SPECIAL : 1;  // flag with ID 0xF000 at bit 0 of byte 0
  u8 FLAG_FOR_SOMETHING_TOTALLY_BORING : 1; // flag with ID 0xF001 at bit 1 of byte 0
  u8 filler;
  u16 VAR_FOR_SOMETHING_SUPER_SPECIAL;      // var with ID 0xF001 at bytes 2 and 3
  u16 VAR_FOR_SOMETHING_TOTALLY_BORING;     // var with ID 0xF002 at bytes 4 and 5
};
```

--------------------------------

### Handle Intro Slide Animation

Source: https://github.com/pret/pokeemerald/wiki/Battle-Controllers

Initiates the background art slide-in animation at the start of a battle. The controller should start animations and then finish handling the command without waiting for completion. Pass the terrain ID as an argument to HandleIntroSlide.

```c
HandleIntroSlide(terrainId);
gIntroSlideFlags |= 1;
```

--------------------------------

### Build pokeemerald

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Commands to enter the project directory and initiate the compilation process.

```bash
cd pokeemerald
make
```

--------------------------------

### Clone and Build agbcc on OpenBSD

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Download the repository and build the agbcc compiler.

```bash
git clone https://github.com/pret/pokeemerald
git clone https://github.com/pret/agbcc
cd agbcc && ./build.sh
./install.sh ../pokeemerald
```

--------------------------------

### Create a simple text script

Source: https://github.com/pret/pokeemerald/wiki/The-Basics-of-Scripting

A basic assembly script using lock, faceplayer, and msgbox to display text to the player.

```gas
Script_SimpleMsgScript::
	lock
	faceplayer
	msgbox Text_SimpleMsgScript, MSGBOX_DEFAULT
	release
	end

Text_SimpleMsgScript:
	.string "Hi!\n"
	.string "My name is Adam.\l"
	.string "What's your name?\p"
	.string "Nice to meet you, {PLAYER}!$"
```

--------------------------------

### Implement Custom Trainer Battle Transition Logic

Source: https://github.com/pret/pokeemerald/wiki/Custom-Battle-Mugshots

In src/battle_setup.c, modify the GetTrainerBattleTransition function to check for and return the custom transition if the trainer has one set. This ensures the custom mugshot is used.

```diff
     if (gTrainerBattleOpponent_A == TRAINER_SECRET_BASE)
         return B_TRANSITION_CHAMPION;

+    if (gTrainers[gTrainerBattleOpponent_A].hasCustomTransition)
+        return gTrainers[gTrainerBattleOpponent_A].transition;
+
     if (gTrainers[gTrainerBattleOpponent_A].trainerClass == TRAINER_CLASS_ELITE_FOUR)
     {

```

--------------------------------

### Update WSL packages

Source: https://github.com/pret/pokeemerald/blob/master/INSTALL.md

Updates the local package index and upgrades installed packages to their latest versions.

```bash
sudo apt update && sudo apt upgrade
```

--------------------------------

### Automating VRAM Tile Allocation with Preprocessor Macros

Source: https://github.com/pret/pokeemerald/wiki/How-Menus-Work-‐-Part-2

Use preprocessor definitions to calculate window tile usage and validate that the total tile count remains within the VRAM budget.

```c
#define WIN_HEADER_WIDTH   26
#define WIN_HEADER_HEIGHT   2
#define WIN_OPTIONS_WIDTH  26
#define WIN_OPTIONS_HEIGHT 14

#define WIN_HEADER_TILE_IDS_USED  (WIN_HEADER_WIDTH  * WIN_HEADER_HEIGHT)
#define WIN_OPTIONS_TILE_IDS_USED (WIN_OPTIONS_WIDTH * WIN_OPTIONS_HEIGHT)

#define WIN_HEADER_BASE_BLOCK  2
#define WIN_OPTIONS_BASE_BLOCK (WIN_HEADER_BASE_BLOCK  + WIN_HEADER_TILE_IDS_USED)
#define END_OF_WINDOW_BLOCKS   (WIN_OPTIONS_BASE_BLOCK + WIN_OPTIONS_TILE_IDS_USED) // ID of first tileset graphic after window tileset graphics

#if END_OF_WINDOW_BLOCKS > 2047
   #error Too many tiles used for windows; total tile count exceeds VRAM budget.
#endif

// divide by 64 and round up
#define FIRST_SAFE_TILEMAP_BASE_INDEX  (END_OF_WINDOW_BLOCKS / 64) + ((END_OF_WINDOW_BLOCKS % 64) ? 1 : 0)

#if FIRST_SAFE_TILEMAP_BASE_INDEX > 31
   #error Too many tiles used; the tilesets themselves may fit in VRAM but there's no safe place to put the tilemap.
#endif
```