libgdx-bullet-physics

libgdx-bullet-physics is a skill for Claude Code from kyu-n/gdx-claude-skills. It costs 80 tokens per session (4,515 once invoked), scanned A, original, MIT.

A libGDX extension for adding 3D physics to Java or Kotlin games through a wrapper around the Bullet physics library.

In plain words
What is it for?
Working with rigid bodies, collision shapes, physics worlds, contact listeners, raycasts, motion states, debug drawing, native-memory cleanup, and related crashes or collision failures.
Why use it?
It documents setup and common collision or movement problems, including the need to manually release native objects because Java garbage collection does not manage their memory.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the gdx-claude-skills plugin — 28 skills shipped together

Good fit Working with rigid bodies, collision shapes, physics worlds, contact listeners, raycasts, motion states, debug drawing, native-memory cleanup, and related crashes or collision failures.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/kyu-n/gdx-claude-skills/libgdx-bullet-physics
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add kyu-n/gdx-claude-skills --skill libgdx-bullet-physics
Clone the repo
git clone --depth 1 https://github.com/kyu-n/gdx-claude-skills

Made for: Claude Code.

Or install gdx-claude-skills, the plugin that ships this one along with the rest of its 28 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for libgdx-bullet-physics

README.md
[![agentmods](https://agentmods.dev/badge/skills/kyu-n/gdx-claude-skills/libgdx-bullet-physics/github.svg)](https://agentmods.dev/skills/kyu-n/gdx-claude-skills/libgdx-bullet-physics)
Your own site
<a href="https://agentmods.dev/skills/kyu-n/gdx-claude-skills/libgdx-bullet-physics"><img src="https://agentmods.dev/badge/skills/kyu-n/gdx-claude-skills/libgdx-bullet-physics/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for libgdx-bullet-physics

Your own site · 80×15
<a href="https://agentmods.dev/skills/kyu-n/gdx-claude-skills/libgdx-bullet-physics"><img src="https://agentmods.dev/badge/skills/kyu-n/gdx-claude-skills/libgdx-bullet-physics.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 80 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,515 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00080 $0.04515
Opus 5 $0.00040 $0.02257
Sonnet 5 $0.00016 $0.00903
Haiku 4.5 $0.00008 $0.00451

Measured 12d ago against content hash cb9398589aba, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

libgdx-bullet-physics scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/libgdx-bullet-physics/SKILL.md · 429 lines

How it starts

The opening of the file, as written. The whole thing — 429 lines — stays where its author put it; the contents beside it link to each section on GitHub.

libGDX Bullet Physics Wrapper

Quick reference for the libGDX Bullet extension (com.badlogic.gdx.physics.bullet.*). This is a JNI wrapper around the C++ Bullet Physics library. All bt* objects are backed by native memory — the Java GC does NOT free them. Manual dispose() is mandatory.

Not supported on HTML5/GWT.

Gradle Dependencies

// core
api "com.badlogicgames.gdx:gdx-bullet:$gdxVersion"
// desktop
implementation "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-desktop"
// android (all four)
natives "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-armeabi-v7a"
natives "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-arm64-v8a"
natives "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-x86"
natives "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-x86_64"
// ios
implementation "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-ios"

Initialization

Bullet.init();  // MUST call before any bt* class. Loads native library. Segfault otherwise.

Three overloads:

Bullet.init()                                   // useRefCounting=false, logging=true
Bullet.init(boolean useRefCounting)              // logging=true
Bullet.init(boolean useRefCounting, boolean logging)

Call once in create(), guard against double-init. Reference counting enables automatic obtain()/release() on shared objects (e.g., btCompoundShape child shapes).

Dynamics World Setup

Five objects, created in this order:

btDefaultCollisionConfiguration collisionConfig = new btDefaultCollisionConfiguration();
btCollisionDispatcher dispatcher = new btCollisionDispatcher(collisionConfig);
btDbvtBroadphase broadphase = new btDbvtBroadphase();
btSequentialImpulseConstraintSolver solver = new btSequentialImpulseConstraintSolver();
btDiscreteDynamicsWorld world = new btDiscreteDynamicsWorld(
    dispatcher, broadphase, solver, collisionConfig);
world.setGravity(new Vector3(0, -10f, 0));  // takes libGDX Vector3, NOT btVector3

Read the full file on GitHub · 429 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 429 lines · 80 tokens per session scan A cb9398589aba

Subscribe to this mod's changes

libgdx-bullet-physics is a skill published in the GitHub repository kyu-n/gdx-claude-skills (4 stars, last pushed 7mo ago), licensed MIT. It adds 80 tokens to every session and 4,515 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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