FixedMathSharp

Deterministic fixed-point math for .NET games, simulations, procedural generation, tooling, and replays.

FixedMathSharp gives you a practical Q32.32 numeric stack—from scalar math and random streams to vectors, transforms, and geometry—without tying your runtime to a game engine. The same inputs follow the same integer-backed math path, which makes the library a strong fit for lockstep simulation, reproducible world generation, and replayable systems.

Why use it?

• Deterministic by design. Fixed64 uses an explicit Q32.32 representation with documented rounding and overflow behavior.
• A complete math toolbox. Vectors, matrices, quaternions, transforms, curves, bounds, rays, segments, triangles, and deterministic random streams share one numeric model.
• Built for difficult inputs. Full-domain intermediate arithmetic prevents premature saturation in fused math, transforms, and geometry queries.
• Engine-agnostic. The core stays portable; engine conventions and interop live at adapter boundaries.
• Serialization choices. Use the standard MemoryPack-enabled package or the Lean variant with no direct MemoryPack dependency.

Install

dotnet add package FixedMathSharp

Targeting Unity? Use the dedicated FixedMathSharp-Unity packages, including a Lean package for Burst-oriented projects.

Quick start

using FixedMathSharp;
using FixedMathSharp.Geometry;

Fixed64 tick = Fixed64.One / 60;
Vector3d velocity = new(6, 0, 2);
Vector3d nextPosition = velocity * tick;

FixedQuaternion turn = FixedQuaternion.FromAxisAngle(
    Vector3d.Up,
    Fixed64.PiOver4);

Vector3d heading = turn.Rotate(Vector3d.Forward);
FixedBoundSphere playArea = new(Vector3d.Zero, new Fixed64(100));

bool inside = playArea.Contains(nextPosition);

All values in the simulation-facing calculation remain fixed point. Convert to float or double only at rendering, editor, or external API boundaries.

Pick a package

Package	Use it for
FixedMathSharp	Core math with MemoryPack support
FixedMathSharp.Lean	The same math surface without a direct MemoryPack dependency
FixedMathSharp.Chronicler	Deterministic record hashes for replay and conformance tooling
FixedMathSharp.Chronicler.Lean	Chronicler extensions on the Lean dependency graph
FixedMathSharp.FluentAssertions	Fluent assertions for fixed-point tests
FixedMathSharp.FluentAssertions.Lean	Fluent assertions paired with the Lean package

Published packages target .NET Standard 2.1 and .NET 8.

Explore the library

• Getting started — package choice, setup, examples, serialization, and source builds
• Wiki — numeric behavior, transforms, conventions, geometry, and formatting
• API reference — public types and members generated from the source XML documentation
• Migration guide — intentional breaking changes and upgrade guidance
• Benchmarks — reproducible BenchmarkDotNet workflows and evidence rules

Community and contributions

Bug reports, feature requests, performance evidence, and real-world determinism stories are welcome. Read CONTRIBUTING.md before opening a pull request, or join the Discord community.

FixedMathSharp is available under the MIT License. See NOTICE for the project branding and redistribution terms.