CAD as Code

Parametric Modeling and Engineering with Python by David M. Straub

A book about building real engineering geometry in code: boundary representations, the mathematics of curves and surfaces, freeform modeling, models you can test and release, meshing, simulation, and searching a design space. It uses CadQuery and the OpenCascade kernel throughout.

Published by HM Munich University of Applied Sciences. DOI 10.60948/OPUS-1358 · URN urn:nbn:de:bvb:m347-opus-13585

Contents

Part I: Parts from Code

1. The Case for CAD as Code
2. First Parts
3. Profiles into Solids
4. Designing with Parameters

Part II: Under the Hood

5. Anatomy of a Solid
6. The Mathematics of Shape
7. Freeform Modeling

Part III: Engineering as Software

8. Models You Can Trust
9. Assemblies and Release Pipelines
10. From Solids to Meshes
11. Simulation
12. Searching the Design Space

Repository layout

Path	Contents
chapters/	The book text, as MyST Markdown
figures/*.py	Scripts that generate every figure
figures/generated/	Their committed output (so the book builds without running them)
figures/static/	Hand-drawn and hand-edited figures
template/	The Typst book template (jtex)
myst.yml	Project and export configuration

Building the book

The PDF build needs only MyST and Typst, because the generated figures are committed.

npm install -g mystmd     # myst v1.10+
# install typst 0.15+ (https://github.com/typst/typst), then:
make build                # -> main.pdf

Typst 0.15 or newer is required (the template uses variable fonts).

Other targets:

make watch     # live preview
make pdfa      # PDF/A-2b output, for archiving
make clean     # remove _build/

Regenerating the figures

Only needed if you change a figure script. This pulls in the full CAD and simulation stack, which is pinned in pyproject.toml and locked in uv.lock:

uv sync --group figures
uv run make figures

Figures are rendered off-screen with PyVista/VTK. Output depends on the GPU and driver, so the same script on another machine gives a visually identical file with different bytes, even at identical package versions. Review a figure change by opening the image.

License

This repository is dual-licensed:

• The book – all prose in chapters/ and all figures in figures/generated/ and figures/static/ – is licensed under Creative Commons Attribution 4.0 International (see LICENSE).
• The code – all code examples in the text, the figure scripts in figures/, and the Typst template in template/ – is licensed under the MIT License (see LICENSE-CODE), so you can lift anything from the book into your own work without attribution obligations.

Citing

See CITATION.cff, or use the "Cite this repository" button on GitHub.

Corrections

If you find an error, please open an issue. See CONTRIBUTING.md.