unity-chem-sim

Rust FFI particle-chemistry simulation core (chemistry_core) plus a standalone Unity package (com.midmanstudio.alembic) built on top of it. Spatial-hashed Lennard-Jones dynamics, velocity Verlet integration, and pairwise bonding, driven by real per-element physics data hand-synced from DixScript-Rust's elements_database.mdix — not a lookup-table magic system. Built for Grand Theft Grimoire, but the package itself doesn't know that; it simulates atoms, nothing game-specific.

Status

chemistry_core (the Rust simulation core) is the mature half: spatial hash, LJ forces, velocity Verlet, and pairwise bonding (unbounded per atom now — real multi-atom molecules, not just diatomic pairs) are all in and tested, currently covering 20 elements. The Unity side (packages/com.midmanstudio.alembic) is still scaffold — Runtime/Core and Runtime/Adapters are placeholders pending C# FFI bindings against the surface documented in docs/getting-started.md.

Build

# Linux / macOS
./scripts/build_rust.sh

# Windows (PowerShell)
.\scripts\build_rust.ps1

This compiles chemistry_core and copies the platform DLL to Assets/Plugins/.

Requirements

• Unity 2022.3 LTS or later
• Rust, stable toolchain, 1.83 or newer (vendored mid-math needs a stable-const f32::from_bits — see docs/getting-started.md for why the older "1.80+" note was wrong)
• Unity packages: com.unity.burst, com.unity.mathematics, com.unity.collections

Architecture

See docs/architecture.md.

License

MIT