cadrum

Rust CAD library powered by OpenCASCADE (OCCT 8.0.0-rc5).

Usage

More examples with source code are available at lzpel.github.io/cadrum.

Add this to your Cargo.toml:

[dependencies]
cadrum = "^0.6"

Build

cargo build automatically downloads a prebuilt OCCT 8.0.0-rc5 binary for the targets below.

For other targets, build OCCT from source:

OCCT_ROOT=/path/to/occt cargo build --features source-build

If OCCT_ROOT is not set, built binaries are cached under target/.

Requirements when building OpenCASCADE from source

• C++17 compiler (GCC, Clang, or MSVC)
• CMake

Examples

Primitives

Primitive solids: box, cylinder, sphere, cone, torus — colored and exported as STEP + SVG.

cargo run --example 01_primitives

//! Primitive solids: box, cylinder, sphere, cone, torus — colored and exported as STEP + SVG.

use cadrum::Solid;
use glam::DVec3;

fn main() {
    let example_name = std::path::Path::new(file!()).file_stem().unwrap().to_str().unwrap();

    let solids = [
        Solid::cube(10.0, 20.0, 30.0)
            .color("#4a90d9"),
        Solid::cylinder(8.0, DVec3::Z, 30.0)
            .translate(DVec3::new(30.0, 0.0, 0.0))
            .color("#e67e22"),
        Solid::sphere(8.0)
            .translate(DVec3::new(60.0, 0.0, 15.0))
            .color("#2ecc71"),
        Solid::cone(8.0, 0.0, DVec3::Z, 30.0)
            .translate(DVec3::new(90.0, 0.0, 0.0))
            .color("#e74c3c"),
        Solid::torus(12.0, 4.0, DVec3::Z)
            .translate(DVec3::new(130.0, 0.0, 15.0))
            .color("#9b59b6"),
    ];

    let mut f = std::fs::File::create(format!("{example_name}.step")).expect("failed to create file");
    cadrum::write_step(&solids, &mut f).expect("failed to write STEP");

    let mut svg = std::fs::File::create(format!("{example_name}.svg")).expect("failed to create SVG file");
    cadrum::mesh(&solids, 0.5).and_then(|m| m.write_svg(DVec3::new(1.0, 1.0, 1.0), true, false, &mut svg)).expect("failed to write SVG");
}

• 01_primitives.step

Write read

Read and write: chain STEP, BRep text, and BRep binary round-trips with progressive rotation.

cargo run --example 02_write_read

//! Read and write: chain STEP, BRep text, and BRep binary round-trips with progressive rotation.

use cadrum::{Solid, Transform};
use glam::DVec3;
use std::f64::consts::FRAC_PI_8;

fn main() -> Result<(), cadrum::Error> {
    let example_name = std::path::Path::new(file!()).file_stem().unwrap().to_str().unwrap();
    let step_path = format!("{example_name}.step");
    let text_path = format!("{example_name}_text.brep");
    let brep_path = format!("{example_name}.brep");

    // 0. Original: read colored_box.step
    let manifest_dir = env!("CARGO_MANIFEST_DIR");
    let original = cadrum::read_step(
        &mut std::fs::File::open(format!("{manifest_dir}/steps/colored_box.step")).expect("open file"),
    )?;

    // 1. STEP round-trip: rotate 30° → write → read
    let a_written = original.clone().rotate_x(FRAC_PI_8);
    cadrum::write_step(&a_written, &mut std::fs::File::create(&step_path).expect("create file"))?;
    let a = cadrum::read_step(&mut std::fs::File::open(&step_path).expect("open file"))?;

    // 2. BRep text round-trip: rotate another 30° → write → read
    let b_written = a.clone().rotate_x(FRAC_PI_8);
    cadrum::write_brep_text(&b_written, &mut std::fs::File::create(&text_path).expect("create file"))?;
    let b = cadrum::read_brep_text(&mut std::fs::File::open(&text_path).expect("open file"))?;

    // 3. BRep binary round-trip: rotate another 30° → write → read
    let c_written = b.clone().rotate_x(FRAC_PI_8);
    cadrum::write_brep_binary(&c_written, &mut std::fs::File::create(&brep_path).expect("create file"))?;
    let c = cadrum::read_brep_binary(&mut std::fs::File::open(&brep_path).expect("open file"))?;

    // 4. Arrange side by side and export SVG + STL
    let [min, max] = original[0].bounding_box();
    let spacing = (max - min).length() * 1.5;
    let all: Vec<Solid> = [original, a, b, c].into_iter()
        .enumerate()
        .flat_map(|(i, solids)| solids.translate(DVec3::X * spacing * i as f64))
        .collect();

    let mut svg = std::fs::File::create(format!("{example_name}.svg")).expect("create file");
    cadrum::mesh(&all, 0.5).and_then(|m| m.write_svg(DVec3::new(1.0, 1.0, 2.0), true, false, &mut svg))?;

    let mut stl = std::fs::File::create(format!("{example_name}.stl")).expect("create file");
    cadrum::mesh(&all, 0.1).and_then(|m| m.write_stl(&mut stl))?;

    // 5. Print summary
    let stl_path = format!("{example_name}.stl");
    for (label, path) in [("STEP", &step_path), ("BRep text", &text_path), ("BRep binary", &brep_path), ("STL", &stl_path)] {
        let size = std::fs::metadata(path).map(|m| m.len()).unwrap_or(0);
        println!("{label:12} {path:30} {size:>8} bytes");
    }

    Ok(())
}

• 02_write_read.brep
• 02_write_read.step
• 02_write_read.stl

Transform

Transform operations: translate, rotate, scale, and mirror applied to a cone.

cargo run --example 03_transform

//! Transform operations: translate, rotate, scale, and mirror applied to a cone.

use cadrum::Solid;
use glam::DVec3;
use std::f64::consts::PI;

fn main() {
    let example_name = std::path::Path::new(file!()).file_stem().unwrap().to_str().unwrap();

    let base = Solid::cone(8.0, 0.0, DVec3::Z, 20.0)
        .color("#888888");

    let solids = [
        // original — reference, no transform
        base.clone(),
        // translate — shift +20 along Z
        base.clone()
            .color("#4a90d9")
            .translate(DVec3::new(40.0, 0.0, 20.0)),
        // rotate — 90° around X axis so the cone tips toward Y
        base.clone()
            .color("#e67e22")
            .rotate_x(PI / 2.0)
            .translate(DVec3::new(80.0, 0.0, 0.0)),
        // scaled — 1.5x from its local origin
        base.clone()
            .color("#2ecc71")
            .scale(DVec3::ZERO, 1.5)
            .translate(DVec3::new(120.0, 0.0, 0.0)),
        // mirror — flip across Z=0 plane so the tip points down
        base.clone()
            .color("#e74c3c")
            .mirror(DVec3::ZERO, DVec3::Z)
            .translate(DVec3::new(160.0, 0.0, 0.0)),
    ];

    let mut f = std::fs::File::create(format!("{example_name}.step")).expect("failed to create file");
    cadrum::write_step(&solids, &mut f).expect("failed to write STEP");

    let mut svg = std::fs::File::create(format!("{example_name}.svg")).expect("failed to create SVG file");
    cadrum::mesh(&solids, 0.5).and_then(|m| m.write_svg(DVec3::new(1.0, 1.0, 1.0), true, false, &mut svg)).expect("failed to write SVG");
}

• 03_transform.step

Boolean

Boolean operations: union, subtract, and intersect between a box and a cylinder.

cargo run --example 04_boolean

//! Boolean operations: union, subtract, and intersect between a box and a cylinder.

use cadrum::{Solid, Transform};
use glam::DVec3;

fn main() -> Result<(), cadrum::Error> {
    let example_name = std::path::Path::new(file!()).file_stem().unwrap().to_str().unwrap();

    let make_box = Solid::cube(20.0, 20.0, 20.0)
        .color("#4a90d9");
    let make_cyl = Solid::cylinder(8.0, DVec3::Z, 30.0)
        .translate(DVec3::new(10.0, 10.0, -5.0))
        .color("#e67e22");

    // union: merge both shapes into one — offset X=0
    let union = make_box
        .union(&[make_cyl.clone()])?;

    // subtract: box minus cylinder — offset X=40
    let subtract = make_box
        .subtract(&[make_cyl.clone()])?
        .translate(DVec3::new(40.0, 0.0, 0.0));

    // intersect: only the overlapping volume — offset X=80
    let intersect = make_box
        .intersect(&[make_cyl])?
        .translate(DVec3::new(80.0, 0.0, 0.0));

    let shapes: Vec<Solid> = [union, subtract, intersect].concat();

    let mut f = std::fs::File::create(format!("{example_name}.step")).expect("failed to create file");
    cadrum::write_step(&shapes, &mut f).expect("failed to write STEP");

    let mut svg = std::fs::File::create(format!("{example_name}.svg")).expect("failed to create SVG file");
    cadrum::mesh(&shapes, 0.5).and_then(|m| m.write_svg(DVec3::new(1.0, 1.0, 2.0), true, false, &mut svg)).expect("failed to write SVG");

    Ok(())
}

• 04_boolean.step

Extrude

Demo of Solid::extrude: push a closed 2D profile along a direction vector.

cargo run --example 05_extrude

//! Demo of `Solid::extrude`: push a closed 2D profile along a direction vector.
//!
//! - **Box**: square polygon extruded along Z
//! - **Oblique cylinder**: circle extruded at a steep angle
//! - **L-beam**: L-shaped polygon extruded along Z
//! - **Heart**: BSpline heart-shaped profile extruded along Z

use cadrum::{BSplineEnd, Edge, Error, Solid};
use glam::DVec3;

/// Square polygon → box (simplest extrude).
fn build_box() -> Result<Solid, Error> {
	let profile = Edge::polygon(&[
		DVec3::new(0.0, 0.0, 0.0),
		DVec3::new(5.0, 0.0, 0.0),
		DVec3::new(5.0, 5.0, 0.0),
		DVec3::new(0.0, 5.0, 0.0),
	])?;
	Solid::extrude(&profile, DVec3::new(0.0, 0.0, 8.0))
}

/// Circle extruded at a steep angle → oblique cylinder.
fn build_oblique_cylinder() -> Result<Solid, Error> {
	let profile = [Edge::circle(3.0, DVec3::Z)?];
	Solid::extrude(&profile, DVec3::new(-4.0, 6.0, 8.0))
}

/// L-shaped polygon → L-beam.
fn build_l_beam() -> Result<Solid, Error> {
	let profile = Edge::polygon(&[
		DVec3::new(0.0, 0.0, 0.0),
		DVec3::new(4.0, 0.0, 0.0),
		DVec3::new(4.0, 1.0, 0.0),
		DVec3::new(1.0, 1.0, 0.0),
		DVec3::new(1.0, 3.0, 0.0),
		DVec3::new(0.0, 3.0, 0.0),
	])?;
	Solid::extrude(&profile, DVec3::new(0.0, 0.0, 12.0))
}

/// Heart-shaped BSpline profile extruded along Z.
fn build_heart() -> Result<Solid, Error> {
	let profile = [Edge::bspline(
		&[
			DVec3::new(0.0, -4.0, 0.0),   // bottom tip
			DVec3::new(2.0, -1.5, 0.0),
			DVec3::new(4.0, 1.5, 0.0),
			DVec3::new(2.5, 3.5, 0.0),    // right lobe top
			DVec3::new(0.0, 2.0, 0.0),    // center dip
			DVec3::new(-2.5, 3.5, 0.0),   // left lobe top
			DVec3::new(-4.0, 1.5, 0.0),
			DVec3::new(-2.0, -1.5, 0.0),
		],
		BSplineEnd::Periodic,
	)?];
	Solid::extrude(&profile, DVec3::new(0.0, 0.0, 7.0))
}

fn main() -> Result<(), Error> {
	let example_name = std::path::Path::new(file!()).file_stem().unwrap().to_str().unwrap();

	let box_solid = build_box()?.color("#b0d4f1");
	let oblique = build_oblique_cylinder()?.color("#f1c8b0").translate(DVec3::new(12.0, 0.0, 0.0));
	let l_beam = build_l_beam()?.color("#b0f1c8").translate(DVec3::new(28.0, 0.0, 0.0));
	let heart = build_heart()?.color("#f1b0b0").translate(DVec3::new(38.0, 0.0, 0.0));

	let result = [box_solid, oblique, l_beam, heart];

	let step_path = format!("{example_name}.step");
	let mut f = std::fs::File::create(&step_path).expect("failed to create STEP file");
	cadrum::write_step(&result, &mut f).expect("failed to write STEP");
	println!("wrote {step_path}");

	let svg_path = format!("{example_name}.svg");
	let mut f = std::fs::File::create(&svg_path).expect("failed to create SVG file");
	cadrum::mesh(&result, 0.5).and_then(|m| m.write_svg(DVec3::new(1.0, 1.0, 1.0), true, false, &mut f)).expect("failed to write SVG");
	println!("wrote {svg_path}");

	Ok(())
}

• 05_extrude.step

Loft

Demo of Solid::loft: skin a smooth solid through cross-section wires.

cargo run --example 06_loft

//! Demo of `Solid::loft`: skin a smooth solid through cross-section wires.
//!
//! - **Frustum**: two circles of different radii → truncated cone (minimal loft)
//! - **Morph**: square polygon → circle (cross-section shape transition)
//! - **Tilted**: three non-parallel circular sections → twisted loft

use cadrum::{Edge, Error, Solid};
use glam::DVec3;

/// Two circles → frustum (minimal loft example).
fn build_frustum() -> Result<Solid, Error> {
	let lower = [Edge::circle(3.0, DVec3::Z)?];
	let upper = [Edge::circle(1.5, DVec3::Z)?.translate(DVec3::Z * 8.0)];
	Ok(Solid::loft(&[lower, upper])?.color("#cd853f"))
}

/// Square polygon → circle (2-section morph loft).
fn build_morph() -> Result<Solid, Error> {
	let r = 2.5;
	let square = Edge::polygon(&[
		DVec3::new(-r, -r, 0.0),
		DVec3::new(r, -r, 0.0),
		DVec3::new(r, r, 0.0),
		DVec3::new(-r, r, 0.0),
	])?;
	let circle = Edge::circle(r, DVec3::Z)?.translate(DVec3::Z * 10.0);

	Ok(Solid::loft([square.as_slice(), std::slice::from_ref(&circle)])?.color("#808000"))
}

/// Three non-parallel circular sections → twisted loft.
fn build_tilted() -> Result<Solid, Error> {
	let bottom = [Edge::circle(2.5, DVec3::Z)?];
	let mid = [Edge::circle(2.0, DVec3::new(0.3, 0.0, 1.0).normalize())?
		.translate(DVec3::new(1.0, 0.0, 5.0))];
	let top = [Edge::circle(1.5, DVec3::new(-0.2, 0.3, 1.0).normalize())?
		.translate(DVec3::new(-0.5, 1.0, 10.0))];

	Ok(Solid::loft(&[bottom, mid, top])?.color("#4682b4"))
}

fn main() -> Result<(), Error> {
	let example_name = std::path::Path::new(file!()).file_stem().unwrap().to_str().unwrap();

	let frustum = build_frustum()?;
	let morph = build_morph()?.translate(DVec3::new(10.0, 0.0, 0.0));
	let tilted = build_tilted()?.translate(DVec3::new(20.0, 0.0, 0.0));

	let result = [frustum, morph, tilted];

	let step_path = format!("{example_name}.step");
	let mut f = std::fs::File::create(&step_path).expect("failed to create STEP file");
	cadrum::write_step(&result, &mut f).expect("failed to write STEP");
	println!("wrote {step_path}");

	let svg_path = format!("{example_name}.svg");
	let mut f = std::fs::File::create(&svg_path).expect("failed to create SVG file");
	cadrum::mesh(&result, 0.5).and_then(|m| m.write_svg(DVec3::new(1.0, 1.0, 1.0), true, false, &mut f)).expect("failed to write SVG");
	println!("wrote {svg_path}");

	Ok(())
}

• 06_loft.step

Sweep

Sweep showcase: M2 screw (helix spine) + U-shaped pipe (line+arc+line spine)

cargo run --example 07_sweep

//! Sweep showcase: M2 screw (helix spine) + U-shaped pipe (line+arc+line spine)
//! + twisted ribbon (`Auxiliary` aux-spine mode).
//!
//! `ProfileOrient` controls how the profile is oriented as it travels along the spine:
//!
//! - `Fixed`: profile is parallel-transported without rotating. Cross-sections
//!   stay parallel to the starting orientation. Suited for straight extrusions;
//!   on a curved spine the profile drifts off the tangent and the result breaks.
//! - `Torsion`: profile follows the spine's principal normal (raw Frenet–Serret
//!   frame). Suited for constant-curvature/torsion curves like helices and for
//!   3D free curves where the natural twist should carry into the profile.
//!   Fails near inflection points where the principal normal flips.
//! - `Up(axis)`: profile keeps `axis` as its binormal — at every point the
//!   profile is rotated around the tangent so one in-plane axis stays in the
//!   tangent–`axis` plane. Suited for roads/rails/pipes that must preserve a
//!   gravity direction. On a helix, `Up(helix_axis)` is equivalent to `Torsion`.
//!   Fails when the tangent becomes parallel to `axis`.
//! - `Auxiliary(aux_spine)`: profile's tracked axis points from the main spine
//!   toward a parallel auxiliary spine. Arbitrary twist control — e.g. a
//!   helical `aux_spine` on a straight `spine` produces a twisted ribbon.

use cadrum::{Compound, Edge, Error, ProfileOrient, Solid, Transform};
use glam::DVec3;

// ==================== Component 1: M2 ISO screw ====================

fn build_m2_screw() -> Result<Vec<Solid>, Error> {
	let r = 1.0;
	let h_pitch = 0.4;
	let h_thread = 6.0;
	let r_head = 1.75;
	let h_head = 1.3;
	// ISO M thread fundamental triangle height: H = √3/2 · P (sharp 60° triangle).
	let r_delta = 3f64.sqrt() / 2.0 * h_pitch;

	// Helix spine at the root radius. x_ref=+X anchors the start at (r-r_delta, 0, 0).
	let helix = Edge::helix(r - r_delta, h_pitch, h_thread, DVec3::Z, DVec3::X)?;

	// Closed triangular profile in local coords (x: radial, y: along helix tangent).
	let profile = Edge::polygon(&[DVec3::new(0.0, -h_pitch / 2.0, 0.0), DVec3::new(r_delta, 0.0, 0.0), DVec3::new(0.0, h_pitch / 2.0, 0.0)])?;

	// Align profile +Z with the helix start tangent, then translate to the start point.
	let profile = profile.align_z(helix.start_tangent(), helix.start_point()).translate(helix.start_point());

	// Sweep along the helix. Up(+Z) ≡ Torsion for a helix and yields a correct thread.
	let thread = Solid::sweep(&profile, &[helix], ProfileOrient::Up(DVec3::Z))?;

	// Reconstruct the ISO 68-1 basic profile (trapezoid) from the sharp triangle:
	//   union(shaft) fills the bottom H/4 → P/4-wide flat at the root
	//   intersect(crest) trims the top H/8 → P/8-wide flat at the crest
	let shaft = Solid::cylinder(r - r_delta * 6.0 / 8.0, DVec3::Z, h_thread);
	let crest = Solid::cylinder(r - r_delta / 8.0, DVec3::Z, h_thread);
	let thread_shaft = thread.union([&shaft])?.intersect([&crest])?;

	// Stack the flat head on top. Screw ends up centered on the origin.
	let head = Solid::cylinder(r_head, DVec3::Z, h_head).translate(DVec3::Z * h_thread);
	Ok(thread_shaft.union([&head])?.color("red"))
}

// ==================== Component 2: U-shaped pipe ====================

fn build_u_pipe() -> Result<Vec<Solid>, Error> {
	let pipe_radius = 0.4;
	let leg_length = 6.0;
	let gap = 3.0;
	let half_gap = gap / 2.0;
	let bend_radius = half_gap;

	// U-shaped path in the XZ plane, centered on origin in X: A↑B ⌒ C↓D.
	let a = DVec3::new(-half_gap, 0.0, 0.0);
	let b = DVec3::new(-half_gap, 0.0, leg_length);
	let arc_mid = DVec3::new(0.0, 0.0, leg_length + bend_radius);
	let c = DVec3::new(half_gap, 0.0, leg_length);
	let d = DVec3::new(half_gap, 0.0, 0.0);

	// Spine wire: line → semicircle → line.
	let up_leg = Edge::line(a, b)?;
	let bend = Edge::arc_3pts(b, arc_mid, c)?;
	let down_leg = Edge::line(c, d)?;

	// Circular profile in XY (normal +Z) translated to the spine start `a`.
	// Spine tangent at `a` is +Z, so the XY-plane circle is already aligned.
	let profile = Edge::circle(pipe_radius, DVec3::Z)?.translate(a);

	// Up(+Y) fixes the binormal to the path-plane normal, avoiding Frenet
	// degeneracy on the straight segments.
	let pipe = Solid::sweep(&[profile], &[up_leg, bend, down_leg], ProfileOrient::Up(DVec3::Y))?;
	Ok(vec![pipe].translate(DVec3::X * 6.0).color("blue"))
}

// ==================== Component 3: Auxiliary-spine twisted ribbon ====================

// 直線 spine を `Auxiliary(&[helix])` で掃引すると、各点で profile の tracked 軸が
// 対応するヘリックス点を向くように回転される。pitch=h のヘリックスは [0, h] の
// あいだにちょうど 360° 一周するので、平たい長方形 profile は 1 回捻れた
// リボンになる — `Fixed` や `Torsion` だと直線 spine では profile は全く
// 回転しないので、ねじれが見えれば Auxiliary が効いている証拠。
fn build_twisted_ribbon() -> Result<Vec<Solid>, Error> {
	let h = 8.0;
	let aux_r = 3.0;

	let spine = Edge::line(DVec3::ZERO, DVec3::Z * h)?;
	let aux = Edge::helix(aux_r, h, h, DVec3::Z, DVec3::X)?;

	// 平たい長方形 (10:1 アスペクト) — 円や正方形ではねじれが見えない。
	let profile = Edge::polygon(&[DVec3::new(-2.0, -0.2, 0.0), DVec3::new(2.0, -0.2, 0.0), DVec3::new(2.0, 0.2, 0.0), DVec3::new(-2.0, 0.2, 0.0)])?;

	let ribbon = Solid::sweep(&profile, &[spine], ProfileOrient::Auxiliary(&[aux]))?;
	Ok(vec![ribbon].translate(DVec3::X * 12.0).color("green"))
}

// ==================== main: side-by-side layout ====================
//
// Each builder places its component at its final world position (screw at
// origin, U-pipe at x=6, ribbon at x=12) and applies its color, so main
// just concatenates them.

fn main() -> Result<(), Box<dyn std::error::Error>> {
	let example_name = std::path::Path::new(file!()).file_stem().unwrap().to_str().unwrap();
	let all: Vec<Solid> = [build_m2_screw()?, build_u_pipe()?, build_twisted_ribbon()?].concat();

	let mut f = std::fs::File::create(format!("{example_name}.step"))?;
	cadrum::write_step(&all, &mut f)?;
	let mut f_svg = std::fs::File::create(format!("{example_name}.svg"))?;
	// Helical threads have dense hidden lines that clutter the SVG; disable them.
	cadrum::mesh(&all, 0.5)?.write_svg(DVec3::new(1.0, 1.0, -1.0), false, false, &mut f_svg)?;
	println!("wrote {example_name}.step / {example_name}.svg ({} solids)", all.len());
	Ok(())
}

• 07_sweep.step

Bspline

cargo run --example 08_bspline

use cadrum::Solid;
use glam::{DQuat, DVec3};
use std::f64::consts::TAU;

// 2 field-period stellarator-like torus.
// `Solid::bspline` is fed a 2D control-point grid to build a periodic B-spline solid.
// Every variation below is invariant under phi → phi+π (or shifts by a multiple
// of 2π), so the resulting shape has 180° rotational symmetry around the Z axis:
//   a(phi)       = 1.8 + 0.6 * sin(2φ)      radial semi-axis
//   b(phi)       = 1.0 + 0.4 * cos(2φ)      Z semi-axis
//   psi(phi)     = 2 * phi                  cross-section twist (2 turns per loop)
//   z_shift(phi) = 1.0 * sin(2φ)            vertical undulation
const M: usize = 48; // toroidal (U) — must be even for 180° symmetry
const N: usize = 24; // poloidal (V) — arbitrary
const RING_R: f64 = 6.0;

fn point(i: usize, j: usize) -> DVec3 {
	let phi = TAU * (i as f64) / (M as f64);
	let theta = TAU * (j as f64) / (N as f64);
	let two_phi = 2.0 * phi;
	let a = 1.8 + 0.6 * two_phi.sin();
	let b = 1.0 + 0.4 * two_phi.cos();
	let psi = two_phi; // twist: 2 full turns per toroidal loop
	let z_shift = 1.0 * two_phi.sin();
	// 1. Local cross-section (pre-twist ellipse in the (X, Z) plane)
	let local_raw = DVec3::X * (a * theta.cos()) + DVec3::Z * (b * theta.sin());
	// 2. Rotate by psi around the local Y axis (major-circle tangent) — the twist
	let local_twisted = DQuat::from_axis_angle(DVec3::Y, psi) * local_raw;
	// 3. Undulate vertically in the local frame
	let local_shifted = local_twisted + DVec3::Z * z_shift;
	// 4. Push outward along the major radius by RING_R
	let translated = local_shifted + DVec3::X * RING_R;
	// 5. Rotate the whole point around the global Z axis by phi
	DQuat::from_axis_angle(DVec3::Z, phi) * translated
}

fn main() {
	let example_name = std::path::Path::new(file!()).file_stem().unwrap().to_str().unwrap();

	let grid: [[DVec3; N]; M] = std::array::from_fn(|i| std::array::from_fn(|j| point(i, j)));
	let plasma = Solid::bspline(grid, true).expect("2-period bspline torus should succeed");
	let objects = [plasma.color("cyan")];
	let mut f = std::fs::File::create(format!("{example_name}.step")).unwrap();
	cadrum::write_step(&objects, &mut f).unwrap();
	let mut f_svg = std::fs::File::create(format!("{example_name}.svg")).unwrap();
	cadrum::mesh(&objects, 0.1).and_then(|m| m.write_svg(DVec3::new(0.05, 0.05, 1.0), false, true, &mut f_svg)).unwrap();
	eprintln!("wrote {0}.step / {0}.svg", example_name);
}

• 08_bspline.step

Features

• color (default): Colored STEP I/O via XDE. Enables write_step_with_colors, read_step_with_colors, and per-face color on Solid.
• source-build: Download and build OCCT from upstream sources via CMake. Enable this on triples without a published prebuilt.

Showcase

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A browser-based configurator that lets you tweak dimensions of a STEP model and get an instant 3D preview and quote. cadrum powers the parametric reshaping and meshing on the backend.

Release Notes

0.6.0

• source-build feature now gates cmake/walkdir as optional build-dependencies. Default cargo build no longer compiles them, significantly reducing build time on prebuilt targets. Users on unsupported targets must enable --features source-build (behavior unchanged — previously these targets also failed, just with a download error instead of a clear message).
• x86_64-pc-windows-gnu prebuilt added via Docker cross-compilation with Debian mingw-w64 (posix thread model). All MinGW runtime DLLs are statically absorbed — the resulting exe depends only on Windows OS DLLs.
• LGPL 2.1 §2 compliance: source builds now retain only the ~9 patched OCCT source files alongside the .a libraries, removing the unmodified bulk (~88 MB of data/dox/tests). The patched files carry timestamped headers per §2(a).
• OCCT_ROOT relative path handling fixed: resolved via env::current_dir() instead of the unreliable CARGO_TARGET_DIR heuristic. --target <triple> flag now works correctly.
• build.rs restructured: resolve_occt uses match chains with #[cfg] for source-build vs prebuilt paths. Source-build code lives in #[cfg(feature = "source-build")] mod source. patch_occt_sources split into walk_occt_sources + patch_or_none (side-effect-free).
• README simplified: Build section moved after Usage with a prebuilt target table + OS icons.

0.5.1

0.4.5 was published briefly but its version number was lower than the already-published 0.5.0 (OCCT 7.9.3, older feature set), so cargo add cadrum would silently pick up 0.5.0 instead of the newer 0.4.5 code. Re-released as 0.5.1 with identical contents. Prefer 0.5.1 over 0.4.5.

• Solid::bspline<const M, const N>(grid, periodic) — new constructor: build a periodic B-spline solid from a 2D control-point grid. V (cross-section) is always periodic; U (longitudinal) is controlled by the periodic flag (torus when true, capped pipe when false). Implemented via GeomAPI_PointsToBSplineSurface::Interpolate over an augmented grid plus SetUPeriodic/SetVPeriodic.
• write_svg / Mesh::to_svg now take shading: bool — opt-in Lambertian shading with head-on light. When true, triangles are tinted by 0.5 + 0.5 * (normal · dir) so curved/organic shapes read clearly; false reproduces the pre-0.5.1 flat rendering. Breaking vs 0.5.0: existing callers must add the flag (pass false to preserve earlier output).
• examples/08_bspline.rs rewritten: 2 field-period stellarator-like torus with twisted + vertically undulating elliptic cross-sections, exercising Solid::bspline and shading=true.
• tests/bspline.rs added: verifies 180° point symmetry of the stellarator shape via XZ/YZ half-space intersection (s1 ≈ s3, s2 ≈ s4).
• Error::BsplineFailed(String) new variant. Breaking for downstream code that does exhaustive match on Error.
• OCCT 8.0.0 deprecation warnings resolved in make_bspline_edge and make_bspline_solid (NCollection_HArray1<gp_Pnt> via local using alias to bypass the Handle() macro comma-splitting issue; NCollection_Array2<gp_Pnt> directly).

License

This project is licensed under the MIT License.

Compiled binaries include OpenCASCADE Technology (OCCT), which is licensed under the LGPL 2.1. Users who distribute applications built with cadrum must comply with the LGPL 2.1 terms. Since cadrum builds OCCT from source, end users can rebuild and relink OCCT to satisfy this requirement.