mvbg

VM_MUSIC_STOP

VM_MUSIC_STOP is a GBVM instruction used to immediately stop the currently playing music track.

Purpose: Controlling music playback is essential for managing the game’s atmosphere and responding to gameplay events. VM_MUSIC_STOP is crucial for:

Silence during cutscenes: Halting background music to emphasize dialogue or sound effects during a cinematic sequence.
Game over/pause screens: Stopping music when the game ends or is paused to create a distinct audio state.
Transitions: Providing a clean break in audio before a new music track begins or when entering a silent area.
Dynamic audio: Creating moments of silence or tension in the game.

When VM_MUSIC_STOP is called, the Game Boy’s audio hardware will cease playing the current music track. The music will fade out or stop abruptly, depending on the music driver’s implementation.

Syntax:

VM_MUSIC_STOP

VM_MUSIC_STOP takes no arguments. It performs a global operation on the currently playing music.

Usage Example: Stopping Music on Game Over

Imagine your game has background music playing during gameplay. When the player’s health reaches zero and the game over screen appears, you want the music to stop to emphasize the game over state.

; In your game over routine:

GAME_OVER_ROUTINE:
  ; Stop any currently playing music
  VM_MUSIC_STOP

  ; Play a game over sound effect (e.g., a short jingle or a dramatic chord)
  VM_SFX_PLAY SFX_GAME_OVER

  VM_FADE_OUT 1 ; Fade screen to black

  VM_LOAD_TEXT TEXT_GAME_OVER
  VM_DISPLAY_TEXT
  VM_INPUT_WAIT .INPUT_ANY ; Wait for any button press to return to title

  VM_RAISE EXCEPTION_CHANGE_SCENE, SCENE_TITLE_SCREEN
  VM_RET

TEXT_GAME_OVER:
  .TEXT "GAME OVER"
  .TEXT_END

SFX_GAME_OVER:
  ; ... sound effect data for game over ...

SCENE_TITLE_SCREEN:
  .R_INT8 0 ; Example scene ID for title screen

In this example, VM_MUSIC_STOP is called at the very beginning of the GAME_OVER_ROUTINE. This immediately silences the background music, creating a more impactful and somber atmosphere for the game over screen. It is then followed by a game over sound effect and a screen fade.

Analogy to Game Boy Development: This is a direct interface with the Game Boy’s audio hardware and music driver. In modern game development, it’s analogous to calling an audio manager function to stop the current background music track:

Unity: AudioManager.StopBGM();
Godot: $MusicPlayer.stop();

It provides the core functionality for controlling the background music in your Game Boy game, allowing for dynamic audio responses to gameplay events and scene changes.