CollisionFix

Fixes Bedrock players getting stuck ("lagback") on bamboo and pointed dripstone when connecting through Geyser/Floodgate, by removing collision from those blocks — but only for the players who actually need it.

What It Does

Bedrock Edition uses a different collision model than Java Edition. On cross-play servers, this causes Bedrock players to rubber-band near certain blocks, most notably bamboo and pointed dripstone. CollisionFix strips the collision box from these blocks, but only for players detected as connecting through Floodgate. Java players and other clients are unaffected.

How It Works

• FloodgateTracker — listens for joins/quits and tags which online players are Bedrock via the Floodgate API
• CollisionGate — a thread-safe registry of currently-online Floodgate player UUIDs
• CollisionAgent — self-attaches a ByteBuddy Java agent at runtime and patches the server's collision-shape method so tracked players get an empty shape
• PlacementGuard — re-validates block placement (bamboo stacking, dripstone thickness/orientation) so builds stay correct once collision is removed
• NMSReflection / ReflectionAPI — version-agnostic, Mojang-mapped reflection helpers for compatibility across Minecraft/Paper versions

Features

• Fixes bamboo collision lag for Bedrock players
• Fixes pointed dripstone collision lag (requires 1.17+)
• Each fix can be toggled independently via collisionfix.conf
• Folia supported
• No effect on Java Edition players
• Soft-depends on Geyser-Spigot / floodgate — safe to install without them, it just won't do anything until Floodgate is present

Caveats

"Fixes" Bedrock players running into lagback issues on certain blocks by removing any collision detection from the given block. Caveats: a custom client — Java or Bedrock — could take advantage of no collision and walk right through. Additionally, placement of these blocks on both platforms may be buggier than usual.

Plugin Info