Command CAD

Command CAD is a data-driven CAD program born from frustration with the current state of CAD software and curiosity about what happens when OpenSCAD is given heavy type safety, functional programming paradigms, and a fully declarative approach.

Note: Command CAD is highly experimental. Do not expect stability in the short term.

A Very Brief Example

let
    nominal_angle_to_sun = 60deg;

    # 30watts per square meter multiplied by square meters results in watts.
    nominal_power_output = (main_body: std.scalar.Length) -> std.scalar.Power:
      let
        # A length * by a length gives an area.
        solar_panel_size = main_body * 1m;
      in
        solar_panel_size * nominal_angle_to_sun::sin() * (30W/1 'm^2');

    # We need 3cm of cooling surface for each watt this produces
    cooling_fin_size = nominal_power_output(main_body = 15cm) / 1W * 3cm;
in
    std.mesh3d.cylinder(
        diameter = cooling_fin_size,
        height = 1cm,
        sectors = 360u,
        stacks = 1u
    )::to_stl(name = "cooling_plate")

Features

Language

• Dimensional analysis — Physical dimensions are tracked at the type level. Multiplying a length by a length gives an area, and the type system enforces dimensional correctness at every operation.
• Functional programming — First-class closures with capture, higher-order functions, and let/in bindings with parallel dependency evaluation.
• First-class types — Types are runtime values accessible via std.types.*, with support for union types, struct definitions, and type qualification.
• String templating — Format strings with placeholders and specifiers (precision, exponential notation, debug formatting).
• Import system — Import and evaluate other .ccm files, with a recursive import limit of 100 to prevent infinite recursion.

Modeling

• 3D mesh generation — Primitives including cube, cylinder, cone, torus, and spheres (icosphere, UV sphere).
• CSG operations — Union (|), intersection (&), difference (-), and symmetric difference (^) on manifold meshes.
• 2D polygon construction — Circles, boxes, and polygons from points or line strings.
• Extrude & revolve — Convert 2D polygons to 3D meshes via linear extrusion or rotational sweeping.
• Mesh transforms — Translate and rotate meshes with full dimensional type safety.

Standard Library

• Math functions — Trigonometric (sin, cos, tan, and inverses), hyperbolic, rounding (floor, ceil, round), absolute value, square root, power, and more.
• Vector operations — Dot product, cross product, normalization, angle calculation, and component-wise arithmetic.
• Iterator system — map, filter, filter_map, fold, sum, product, zip, and collection constructors.
• Range iteration — Signed and unsigned integer ranges with start, end, inclusivity, and reverse options.
• Export — Export meshes to STL and 2D geometry to SVG.

Tooling

• CLI REPL — Interactive read-eval-print loop powered by reedline (the same library behind nushell).
• File evaluation — Evaluate a .ccad file and all its dependencies from the command line.
• Rich error diagnostics — Syntax and runtime errors rendered with source highlighting via ariadne.
• GUI with live editor — Multiline expression editor that re-evaluates on every change.
• 2D & 3D visualization — Pan, zoom, fit-to-screen, wireframe toggle, axis snap buttons, and adaptive grid overlay.
• Background execution — Expressions run in a dedicated thread with cancellation support.
• Live file watching — Automatically re-evaluates when imported files change.

Constraint Solving (experimental)

Define equation systems with the <<<variables: lhs == rhs>>> syntax. Supports multiple variables and relations (==, <, <=, >=, >, !=). This feature is experimental and under active development.

Planned Features

• Constraint solving stabilization — Bringing the constraint/equation solver to a stable, production-ready state.
• Implicit surface modeling — Using fidget for SDF-based implicit surface operations.
• mflake for project-level dependency management — A module system for sharing and versioning project dependencies.

Getting Started

Prerequisites

• Nix with flakes support (or nix-userccs)

Development Shell

nix develop        # default shell (includes GUI dependencies)
nix develop .#core # core only, no GUI dependencies

Building

# From within the nix develop shell
cargo build --all-features

Running

# REPL mode
cargo run --bin ccad -- repl

# Evaluate a file
cargo run --bin ccad -- file <path>

Examples

Browse working examples in the examples directory, organized by category: language features, 3D mesh modeling, and other demonstrations.

License

This project is licensed under the GNU Affero General Public License v3.0 (AGPL-3.0-only) or, at your option, any later version. See COPYING for details.