Engine-agnostic isosurface extraction. Field in, triangles out.

isomesh has to serve both a real-time voxel game and a CAD tool, and that single constraint decides most of its design: no math library appears in a public signature, output buffers are caller-provided and reusable, and the scalar type is generic over f32 and f64.

Conventions

These hold for every type and every algorithm in this crate. They are stated once here and repeated on the items they constrain, because each one is a convention rather than a fact, and a mismatch across a module boundary produces output that looks plausible and is wrong.

• Sign. Negative is inside. A field is negative strictly inside the solid, positive strictly outside, and the surface is the zero level set.
• Handedness. Right-handed. x × y = +z.
• Winding. Counter-clockwise viewed from outside the solid.
• Normals. Point away from the solid, i.e. along increasing field value.
• Index order. x varies fastest: i = x + y·sx + z·sx·sy.

Float math

Every transcendental goes through [libm], unconditionally — there is no std fast path. Two reasons. One execution path: a #[cfg(feature = "std")] fork would mean two float backends and two sets of results for the same input. And determinism: std's sin/cos are the platform's, are not correctly rounded, and differ between macOS and Linux, which would make committed golden hashes platform-specific. It costs nothing at run time — libm::sqrtf compiles to fsqrt on aarch64+neon and sqrtss on x86-64+sse2.

no_std

This crate is no_std unconditionally, not cfg_attr-conditionally. A conditional attribute would put std's prelude in scope for the default build, so a stray use std::collections::HashMap would compile here and break only in some later no_std build. Unconditional makes that a compile error at the moment it is typed.