Gravitas 2.0.1

Gravitas

Deterministic fixed-point physics for lockstep games and simulations.

Gravitas gives .NET simulations a physics runtime that can replay the same inputs into the same results. It combines fixed-point 2D, 3D, and explicit mixed-dimension physics with context-owned worlds, stable collision ordering, continuous collision detection, queries, constraints, replay hashes, and renderer-neutral diagnostics.

Why Gravitas?

• Lockstep by design. Authoritative physics uses deterministic fixed-point math and explicit fixed-frame phases.
• One runtime, three paths. Run pure 2D, pure 3D, both side by side, or deliberate 2D/3D contacts through mixed mode.
• A complete collision stack. Build with primitives, convex and concave meshes, compounds, materials, manifolds, response islands, CCD, joints, and ragdolls.
• Continuous static environments. Declare exact continuity between bounded mesh or planar pieces while retaining collider identities, materials and spatial partitions. See static surfaces.
• No engine lock-in. Hosts provide transforms and lifecycle calls through a small adapter boundary; Gravitas owns no renderer, scene graph, or ECS.
• Tools without hidden state. Context-local queries, replay hashes, diagnostic events, and debug-draw commands make simulation behavior visible without changing it.

Runtime geometry follows an explicit supported size contract: an inclusive 4,096-unit conservative reach per collider or context query source, independent of world position and travel distance.

Install

dotnet add package Gravitas

Prefer the dependency-light serialization profile?

dotnet add package Gravitas.Lean

Both packages target netstandard2.1 and net10.0.

The Core Loop

Gravitas makes simulation ownership visible. A host owns commands and timing; one GravitasWorldContext owns the physics world and all of its runtime services.

using Gravitas;

using GravitasWorldContext context = GravitasWorldContext.CreateOwned();
context.SetFrameRate(60);

// Configure GridForge coverage, then bind host agents, bodies, and colliders.
// Apply the frame's deterministic commands before advancing physics.
context.Simulate();
context.LateSimulate();

var replayHash = context.ComputeReplayHash();

// Presentation is separate from authoritative simulation state.
context.Visualize();
context.LateVisualize();

The full Getting Started guide creates the grid, host adapter, collider, and dynamic body behind that loop.

What You Can Build

Shared logging and exception guards come from the independent Chronicler.Diagnostics package. See the migration guide for the updated imports and guard names.

Documentation

• Getting Started — build and step your first world.
• Guides — understand host integration, dimensions, collisions, queries, replay, and diagnostics.
• Workload and Tuning — set a host tick budget and compare first-use and warmed workload costs.
• API Reference — browse public namespaces, types, and members.
• Coverage Report — inspect the current test-suite coverage.
• Migration Guide — update body mass access, Chronicler imports, clock consumers, and persisted timing data across intentional contract changes.
• Contributing — build, test, and prepare a focused change.

Built On The LSF Stack

Gravitas is the physics layer in a modular deterministic simulation stack:

Contributing

Contributions are welcome. Start with CONTRIBUTING.md; the deeper deterministic, physics, testing, and performance rules live in AGENTS.md.

For questions and discussion, join the community on Discord.

License

Gravitas is available under the MIT License. See NOTICE and COPYRIGHT for attribution details.