CultMath

Clean-room math shaped for people who think in HLSL.

CultMath provides lowercase vector types, shader-style intrinsics, and native hot-path kernels so math-heavy renderer code can move between C#, Rust, and HLSL without turning every line into a translation exercise. It is not a Unity.Mathematics clone. It is a small, Aquarium-born library built from public shader semantics.

Current Surface

float2, float3, float4
component-wise arithmetic
scalar-to-vector splats
swizzles for common lanes
conversions to and from System.Numerics
math intrinsics: radians, degrees, abs, floor, ceil, frac, min, max, clamp, saturate, lerp, step, smoothstep, dot, cross, length, distance, normalize, and reflect
Voronoi.SampleTones, a C# batch surface that calls the Rust cultmath-core native kernel when cultmath_core is available and falls back to the managed parity path otherwise.

Native Core

The canonical hot-path body lives in native/cultmath-core. It exports a C ABI for batch kernels such as cultmath_apollonian_voronoi_tones.

Runtime wrappers own syntax and integration. Rust owns optimized primitive kernel behavior and parity fixtures.

Example

using CultMath;

float3 normal = math.normalize(new float3(0.25f, 1.0f, -0.1f));
float rim = math.saturate(1.0f - math.dot(normal, new float3(0.0f, 0.0f, -1.0f)));
float glow = math.smoothstep(0.2f, 1.0f, rim);

Build

dotnet build CultMath.slnx
dotnet test CultMath.slnx
cargo test --manifest-path native/cultmath-core/Cargo.toml
cargo build --release --manifest-path native/cultmath-core/Cargo.toml

Doctrine

The goal is mechanical sympathy between CPU-side authoring, native kernels, and GPU-side shader math. If an intrinsic exists here, it should behave like the shader concept unless a runtime's numeric rules make that impossible. Weird deviations get tests and documentation, not folklore.

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