openscad_cpp_evaluator

A C++20 port of openscad_evaluator (Python): an AST-walking geometry engine that takes a parsed OpenSCAD AST and produces Manifold CSG geometry, ready to export to STL/OBJ/OFF/3MF or hand off to a renderer.

Built on:

• openscad_cpp_parser (git submodule) for lexing/parsing/AST/scope resolution.
• Manifold v3.5.2 for the actual CSG boolean/mesh engine.
• Boost.Polygon for roof()'s Voronoi-diagram construction.
• nothings/stb (header-only) for surface()'s image loader and the built-in font provider's TrueType parsing/rasterization.

All fetched automatically via CMake FetchContent — no manual dependency installation beyond the toolchain below.

Status

All planned phases (0–9) are complete: the full primitive/transform/boolean/modifier/control-flow language surface, every builtin function, STL/OBJ/OFF/3MF import and export, hull()/minkowski()/ linear_extrude()/rotate_extrude()/roof()/offset()/surface()/DXF & SVG import/text(), an opt-in content-hash geometry cache, per-call-site profiling, and a gdb-style --debug REPL. See CLAUDE.md for the full phase-by-phase history and architecture notes.

Build

Requires:

• CMake ≥ 3.24
• A C++20 compiler (Clang, GCC, or MSVC — all three are covered by CI)
• Bison ≥ 3.8 and Flex
  • macOS: brew install bison flex (the system bison is too old; CMake auto-detects Homebrew's)
  • Linux: sudo apt-get install bison flex
  • Windows: MSYS2's bison/flex (pacman -S bison flex) — GitHub's windows-latest runner ships MSYS2 pre-installed at C:\msys64; CMake auto-detects it there too

GoogleTest and every other C++ dependency are fetched automatically.

git clone --recurse-submodules <this-repo>
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j

(Omitting -DCMAKE_BUILD_TYPE=Release builds unoptimized — pass it explicitly for anything performance-sensitive.)

On Windows, CMake defaults to the multi-config Visual Studio generator, which ignores CMAKE_BUILD_TYPE; pass --config Release to cmake --build (and -C Release to ctest) instead.

Test

ctest --test-dir build --output-on-failure

Run a single binary or filter:

build/tests/oscad_eval_tests
build/tests/oscad_eval_tests --gtest_filter='FormatNumber.*'

The suite runs twice in CI — once with the bytecode VM on (the default) and once with it off (OSCAD_BYTECODE_VM=0) — so a regression in either the compiled or interpreted expression-eval path is caught.

CLI

build/tools/cli/openscad-cpp-evaluator <input.scad> -o <output.{stl,obj,off,3mf}> [--format stl|obj|off|3mf] [--debug]

The output format is inferred from -o's extension, or set explicitly with --format. --debug drops into a gdb-style REPL (break/run/continue/step/next/finish/print/ backtrace/set/list/quit/help) before and during evaluation.

build/tools/cli/openscad-cpp-evaluator model.scad -o model.stl

Architecture

See CLAUDE.md for the full per-file architecture map, the Python-reference cross-check history, and the rationale behind every non-obvious design choice (the two-pass resolve/generate CSG pipeline, the FontProvider injection seam, the closure-detection rule, etc.).

CI

GitHub Actions builds and tests on Linux, macOS, and Windows on every push/PR (.github/workflows/ci.yml).