**denizen-bulletphys — a real rigid-body physics engine for Denizen.** Falling blocks with inertia and rotation, collisions between bodies and with the terrain, and vehicles on raycast suspension that reacts directly to the blocks under their wheels.

--- > **Status: 1.0.0-alpha.** The falling-blocks command and the vehicle/suspension > command are both implemented and working on a live server. What's still missing > for a real 1.0: Denizen ObjectTags/events for bodies and vehicles (right now > they're addressed by a plain numeric id). ## How it works The actual physics runs on **libbulletjme** (a JNI binding to Bullet) on its own thread, stepped at a fixed 60 Hz — decoupled from server TPS. Once per game tick, the main thread reads an immutable snapshot of every body's transform and reflects it into the world through `block_display` entities with client-side interpolation. MC blocks around active bodies are streamed into a static Bullet collider (loaded/unloaded as bodies move, not a fixed radius around a spawn point) — that's what falling blocks and vehicle wheels actually rest and collide against. ``` main thread (20 TPS) ──commands/terrain──► physics thread (60 Hz, Bullet) ▲ │ └────────── transform snapshot ◄─────────────┘ │ block_display (client-side interpolation) ``` ## Using it from Denizen ``` - physicsbody spawn [] (material:) (size:<#.#>) (mass:<#.#>) (count:<#>) - physicsvehicle spawn [] (mass:<#.#>) (size:<#.#>,<#.#>,<#.#>) (material:) (save:) - physicsvehicle <#(id)> addwheel offset:<#.#>,<#.#>,<#.#> (radius:<#.#>) (resting:<#.#>) (steering:) - physicsvehicle <#(id)> drive (wheel:<#>) (steer:<#.#>) (throttle:<#.#>) (brake:<#.#>) - physicsvehicle <#(id)> remove ``` ## Why libbulletjme, not ode4j/jbullet jBullet has been abandoned since 2008. ode4j is pure Java, but its raycast vehicle suspension would have had to be hand-rolled. libbulletjme is actively maintained, ships `PhysicsVehicle` with working suspension out of the box, and is already used by the DynamX physics mod for Minecraft. ## Requirements | | | |---|---| | Java | 21+ (one jar runs on both 1.21.x / Java 21 and 26.x / Java 25) | | Server | Paper 1.21.x+ (tested on Leaf 26.2) | | Denizen | 1.3.3+ | | Engine | libbulletjme 23.1.0 — natives for Linux x64/ARM64, Windows x64, macOS x64/ARM64 bundled in the jar | ## License All Rights Reserved.

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