OrcaSlicer/docs/CAD/design_tab_pr_description.md

Design (CAD) tab — upstream pull request

What this adds

A sketch-first parametric CAD tab inside the slicer. The workflow is direct: sketch → constrain → solid features → commit to plate. The whole feature recipe is persisted inside the 3MF, so reopening restores an editable model rather than a frozen mesh.

• Kernel: OCCT, which upstream already links for STEP import — see cad_dependency_weight.md
• Constraint solver: vendored SolveSpace libslvs subset
• Interaction model: object-driven — point at geometry, the geometry offers the verbs that apply to it; see cad_ux_guidelines.md
• Full user-facing documentation: design_tab.md

Why it belongs in the slicer

Every round trip through an external CAD tool costs a file export, a re-import, and the design intent that both steps discard. A part modified after slicing should return to its feature history, not to a mesh. Keeping the CAD model inside the slicer preserves that loop — the nozzle diameter, the build volume and the material are known at design time.

For the integration case in full: design_tab_upstream_portability.md.

How it is built

The SLIC3R_CAD CMake flag (default ON) gates the entire tab. With it OFF the tab is not compiled and the deps prefix matches upstream exactly — the dependency diff is one line in OCCT's CMake: BUILD_MODULE_ModelingAlgorithms=OFF → ON.

Measured cost table: cad_dependency_weight.md.

Diff shape

Against merge-base d6cb667b894f:

306 files changed, 83032 insertions(+), 777 deletions(-)

350 commits, of which 284 are new files and 37 modify upstream files. 99.3 % of the diff is new code. The negotiable surface is the 37 modified files.

Tests

205 TEST_CASE blocks across 6 new test source files. This counts assertions written, not assertions passed — a run needs a build.

scripts/CAD/run-kernel-tests.sh is the headless verification contract: it builds only libslic3r_tests (not the GUI app), needs no display, and exit 0 means the CAD suite passed. It now runs with no exclusions — both cases that used to be quarantined (the circle-line tangency solver abort and the internal-thread reference) are fixed.

Licensing

The vendored solver in src/libslic3r/slvs/ is GPL-3.0 (see src/libslic3r/slvs/LICENSE), not LGPL. The combined work is distributable under AGPL-3.0. See the Licensing section of design_tab_upstream_portability.md for the AGPLv3/GPLv3 compatibility argument; this point should be confirmed with upstream explicitly.

Not verified

• Card wiring for 9 of the 16 late-wired tools was never click-tested.
• There is no automated GUI test in CI. A green kernel run says nothing about the GUI — synthetic clicks never drift, so the test suite and the viewport are two separate realities.
• The click-test defect rate has not converged: a second pass found no new defects, but four further days of work found five more. The earlier pass is not evidence of stability.

Reviewer's map

See the Where the code lives table in the user doc for the file-to-role mapping, and docs/ux/tool_atlas.json as the generated-from source of src/slic3r/GUI/CAD/DesignOffer.hpp.