The kernel boundary and truck

crates/kernel is SolidCraft’s B-rep kernel. It wraps truck (Apache-2.0) for topology, NURBS geometry, booleans, tessellation and STEP parsing, and it is the only crate allowed to use truck. Callers get SolidCraft types (Body, face and edge indices, meshes, measures) and a KernelError instead of truck types and panics.

guard

truck can panic on geometry it doesn’t handle. Every call into it goes through solidcraft_kernel::guard, which catches the panic and turns it into KernelError::Internal, leaving the model unchanged:

#![allow(unused)]
fn main() {
pub fn guard<T>(what: &str, f: impl FnOnce() -> Result<T>) -> Result<T>
}

A failing feature shows an error on the timeline; it never takes the app down.

What is our own

truck has no fillets, chamfers, shells or face edits, so these are SolidCraft code in the kernel: constant, chord and variable-radius fillets with corner blends, chamfers, shell and offset, Delete Face, Split Face, Replace Face, sewing, STEP and IGES reading and writing beyond truck’s parser, and face provenance (which input face each output face came from, for persistent naming).

Vendored truck crates

Patched copies of truck-shapeops, truck-stepio and truck-meshalgo live in vendor/, wired in with [patch.crates-io]. The patches fix robustness bugs found by our tests and the STEP corpus. vendor/ is excluded from our fmt and clippy rules, and each patch should go upstream when it can.

Equal cylinders crossing each other (tangent_cylinders.rs) touch at two points, which truck’s mesh-based intersection cannot trace through. When a boolean of such a pair fails, the kernel splits both cylinder faces along the line through the touching points and takes the boolean of the split bodies; the shapeops patch that picks the corner of a face at a vertex several curves end on makes the arms of the crossing connect.

Some truck assertions only run in debug builds and can fail on valid geometry, so tests and CI run with --release.