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.
npx skills add curiositech/some_claude_skills --skill physics-rendering-expertgit clone --depth 1 https://github.com/curiositech/some_claude_skillsWrote 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.
[](https://agentmods.dev/skills/curiositech/some_claude_skills/physics-rendering-expert)<a href="https://agentmods.dev/skills/curiositech/some_claude_skills/physics-rendering-expert"><img src="https://agentmods.dev/badge/skills/curiositech/some_claude_skills/physics-rendering-expert/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.
<a href="https://agentmods.dev/skills/curiositech/some_claude_skills/physics-rendering-expert"><img src="https://agentmods.dev/badge/skills/curiositech/some_claude_skills/physics-rendering-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00127 | $0.01387 |
| Opus 5 | $0.00063 | $0.00694 |
| Sonnet 5 | $0.00025 | $0.00277 |
| Haiku 4.5 | $0.00013 | $0.00139 |
Grade A, and why
physics-rendering-expert 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 5d 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.
How it starts
The opening of the file, as written. The whole thing — 146 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Physics & Rendering Expert: Rope Dynamics & Constraint Solving
Expert in computational physics for real-time rope/cable dynamics, constraint solving, and physically-based simulations.
When to Use This Skill
Use for:
- Real-time rope/cable/chain simulation (leashes, climbing ropes)
- Position-Based Dynamics (PBD) implementation
- Constraint solvers (Gauss-Seidel, Jacobi)
- Quaternion/dual-quaternion rotation math
- Verlet integration for particle systems
- Tangle detection (multi-rope collisions)
Do NOT use for:
- Fluid dynamics → specialized SPH/MPM solvers
- Fracture simulation → requires FEM or MPM
- Offline cinematic physics → different constraints
- Unity/Unreal physics → use built-in systems
Expert vs Novice Shibboleths
| Topic | Novice | Expert |
|---|---|---|
| Constraint approach | Uses spring forces (F=ma) | Uses PBD (directly manipulates positions) |
| Why PBD | "Springs work fine" | Springs require tiny timesteps; PBD is unconditionally stable |
| Solver choice | "Just iterate until done" | Gauss-Seidel for chains, Jacobi for GPU |
| Iterations | 20+ iterations | 5-10 is optimal; diminishing returns after |
| Rotation | Uses Euler angles | Uses quaternions (no gimbal lock) |
| Integration | Forward Euler | Verlet (symplectic, energy-conserving) |
Common Anti-Patterns
Force-Based Springs for Stiff Constraints
| What it looks like | Why it's wrong |
|---|---|
force = k * (distance - rest_length) with high k |
High k requires tiny dt for stability; low k gives squishy ropes |
| Instead: Use PBD - directly move particles to satisfy constraints |
Euler Angles for Rotation
| What it looks like | Why it's wrong |
|---|---|
rotation = vec3(pitch, yaw, roll) |
Gimbal lock at 90° pitch; unstable composition |
| Instead: Use quaternions - 4 numbers, no gimbal lock, stable SLERP |
Over-Iteration
| What it looks like | Why it's wrong |
|---|---|
solver_iterations = 50 |
Diminishing returns after 5-10; wastes cycles |
| Instead: Use 5-10 iterations; if more needed, use XPBD compliance |
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 5d ago First seen · 146 lines · 127 tokens per session scan A 6d922e793f16
physics-rendering-expert is a skill published in the GitHub repository curiositech/some_claude_skills (216 stars, last pushed 2d ago), licensed MIT. It adds 127 tokens to every session and 1,387 once invoked, about $0.0006 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 2026-09-03.
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