BGM Fields (Forge 1.20.1)

🎥 **Watch the BGM Fields demo:**  
https://www.youtube.com/shorts/meaJewowPdg

BGM Fields lets you place Realm Blocks that create server-authoritative “BGM zones” (Realms). When a player is inside a Realm, the Realm can:

• Switch BGM (single track or playlist)
• Apply “Vision” visuals (fog / overlay / sky-only tint / particles / colored precipitation)
• Optionally render a glowing boundary ring (visible from inside and outside)

This mod does not send .ogg audio files over the network. Music is referenced by Sound Event IDs; you provide the actual audio via a client resource pack (per-player) or a server-pushed resource pack.

Requirements

• Minecraft 1.20.1
• Forge 47.x
• Java 17

Multiplayer: install the mod on both the server and all clients.

Getting Started

1) Craft and place a Realm Block.

2) Right-click the Realm Block to open the settings screen.

3) Set:

• Radius (max 300)
• Y-range (optional; you can limit the realm vertically)
• Realm color (used by visuals)
• BGM settings (track or playlist)
• Per-realm BGM volume (0–100, default 80)

Only the owner can edit the Realm. OPs (permission level 2) can also edit.

Realm Placement Rules

• If another player’s Realm overlaps the new one, placement is denied.
• Even for the same owner, partial overlap is denied.
• Full nesting is allowed (one Realm completely inside the other).

BGM: How Tracks Work

A track is a Sound Event ID (namespace:path). Examples:

• Vanilla music: minecraft:music.overworld
• User BGM generated by this mod: bgmfieldmod:bgm.my_song

BGM Modes:

• Single: play one Sound Event.
• Playlist: multiple entries; each entry has:
  • track (Sound Event ID)
  • loop (true/false)

Add Your Own Music (Client-side, per player)

BGM Fields auto-creates a folder resource pack called:

• BGMFields_UserBGM

Put your .ogg files under:

resourcepacks/BGMFields_UserBGM/assets/bgmfieldmod/sounds/bgm/

Then reload resources (in-game “Reload” button or F3+T).

You do not need to write sounds.json yourself; BGM Fields generates it automatically.

Sound ID mapping:

• my_song.ogg → bgmfieldmod:bgm.my_song
• dungeon/boss.ogg → bgmfieldmod:bgm.dungeon.boss

Notes:

• Filenames are sanitized to valid resource paths (spaces, uppercase, etc. are converted).
• The resource pack still needs to be enabled in Minecraft’s Resource Packs menu (that is vanilla behavior). There is also an optional client config that can attempt to auto-enable it.

Provide Music to Everyone (Server Resource Pack Push)

BGM Fields can ask clients to apply a server resource pack on join.

Two modes:

• external-url: set serverResourcePack.url to a public URL to a .zip resource pack.
• internal-http: leave serverResourcePack.url empty; the server hosts the .zip via a built-in HTTP server.

Config keys (in the Forge common config):

• serverResourcePack.enabled
• serverResourcePack.required
• serverResourcePack.publicHost
• serverResourcePack.url
• serverResourcePack.port
• serverResourcePack.packFile
• serverResourcePack.sha1
• serverResourcePack.prompt

Zip requirements:

• pack.mcmeta and assets/ must be at the zip root (zipping the parent folder often breaks this).

Vision (Visual Effects)

Each Realm has a “Vision” visual module (server-authoritative settings synced to nearby clients). You can control:

• Master enable
• Strength (0–100)
• Ramp up/down (fade in/out)
• Fog
• Overlay
• Sky Tint (sky-only)
  • Gradient is optional
  • Can follow the realm color or use an independent RGB
• Particles
• Colored precipitation (rain/snow via custom particles)
• Boundary visualization (glowing ring)

Realm Vision Keybind (Owner Utility)

There is a client keybind:

• V = toggle “Realm Vision” ON/OFF

This is used for owners to reveal the real Realm Block when the Realm is disguised:

• Owner + Realm Vision ON + Sneak (Shift) → show the real block

Commands (OP)

• /bgmfields_rp start
• /bgmfields_rp stop
• /bgmfields_rp send
• /bgmfields_rp reload

Notes / Tips

• If your particle setting is “Minimal”, some Vision particles/precipitation may be hard to see.
• The boundary ring is designed to be visible both from inside and outside the Realm (useful for large radii).