ZOZO's Contact Solver 🫶

A contact solver for physics-based simulations involving 👚 shells, 🪵 solids, 🪢 rods, 🧱 rigid bodies and ⏳ sand. Started as an in-house physics engine at ZOZO, Inc., the largest fashion e-commerce company in Japan, and now evolving with the community. All open-source.

🤖 LLM Transparency: We highly respect that readers expect to hear the author's original voice and tone, which we work to retain throughout. Our use of LLMs is clarified in (Markdown).

⚖️ Criticism for Fairness: Criticism of this solver exists, and we share it for fairness. See our summary (Markdown).

📌 TL;DR

To use this through Blender, watch the CGMatter walkthrough. Release download is here and the video tutorials are here. Read public criticism (Markdown) and Disclaimer and Limitations before use.

⚠️ When not in use, disable or uninstall our add-on. Undiscovered bugs may affect performance, auto-save, or other parts of Blender in unexpected ways (e.g., #36 and #145, both fixed).

👀 Quick Look

🎨 Simulate remotely from our Blender add-on (screenshots taken on macOS; you can also run locally on a modern NVIDIA GPU on Windows or Linux, or on an Apple silicon Mac)

https://github.com/user-attachments/assets/f266111e-7380-428b-8a3c-25eac4f039e5

🚀 Or run it locally: ./ppf-contact-solver (macOS/Linux), double click start.bat (Windows), or a Docker command (Linux/Windows)

🌐 Click the URL and explore our examples

🚧 Disclaimer and Limitations

• ⏳ Offline use: Not real time, though some examples reach interactive rates.
• 🐢 Not the fastest: Other recent work reports faster results.
• 📉 Not differentiable: No gradients, so inverse design and learning are out of scope.
• 🧪 Not production ready (yet): Many bugs remain, including undiscovered ones. We are actively working to make it production-proof. Known bugs are tracked in Issues.
• 🔌 Disable when not in use: Disable or uninstall the add-on when you are not using it. Undiscovered bugs may affect performance, auto-save, or other parts of Blender in unexpected ways (e.g., #36 and #145, both fixed).
• 🐌 CPU and Metal backends are slow: Meant for evaluation, learning, and small examples. Larger scenes need a powerful GPU.
• 🟥 AMD GPUs not tested every version: The ROCm backend has run on real AMD hardware (see the discussion), but the author owns no AMD hardware and does not test every version. We rely on community bug reports.
• 🛠️ Add-on setup takes effort: Not one click. The solver backend is deployed separately, locally or remotely.
• 👤 Development pace: Maintained by Ryoichi Ando alone, with limited time.
• ⚖️ Criticism exists: We share critical comments from community videos for fairness (Markdown).

This is the beginning of the README. Read the rest at the original. Read the full README ↗