1aa3493e7d673b945472daa64632804acf64bfa4
2 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Tarik Moussa
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039cc26e36 |
Phase 8b-Lite: pipe-operator chaining for named parameters
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Adds `operator|` in `namespace CGAL` so package-local named parameters
can be combined left-to-right without modifying CGAL upstream:
auto p = CGAL::parameters::gradient_tolerance(1e-12)
| CGAL::parameters::max_iterations(500)
| CGAL::parameters::output_uv_map(uv);
CGAL::discrete_conformal_map_euclidean(mesh, p);
Why not the canonical `.a().b().c()` syntax
───────────────────────────────────────────
CGAL's standard chaining mechanism requires registering each named
parameter as a member function on `Named_function_parameters` via the
`CGAL_add_named_parameter` macro in
`CGAL/STL_Extension/internal/parameters_interface.h` — a vendored
upstream file that conformallab++ deliberately treats as read-only.
Adding member-function chainers for our package-local tags would
require either forking CGAL or modifying the vendored copy. Neither
is acceptable for a library that wants to remain portable across
future CGAL releases.
The pipe-operator achieves the same compositional semantics via a
free function in `namespace CGAL` (so ADL finds it for
`Named_function_parameters` operands). Implementation: rebuild the
right-hand-side `Named_function_parameters` with the left-hand-side
as its `Base`, producing an indistinguishable chain that every entry
function accepts unchanged.
Implementation: `code/include/CGAL/Conformal_map/internal/parameters.h`
lines 158-187. The operator is constrained to right-hand-sides with
`No_property` base (i.e. fresh single-parameter packs from the helper
functions), so it never collides with any future CGAL operator on the
same type.
Tests (2 new, total Phase-8b-Lite suite 15 → 17)
────────────────────────────────────────────────
* CGALPhase8bLite.NamedParamPipe_MultipleParamsTakeEffect
Chain three parameters; verify all three take effect (tight
tolerance respected + UV pmap populated + iteration cap honoured).
* CGALPhase8bLite.NamedParamPipe_TwoParams
Chain two parameters; verify max_iterations(0) blocks the loop
even when combined with another param.
Full CGAL suite: 234/234 PASSED, 0 SKIPPED (was 232).
Total: 257/257 PASSED, 0 SKIPPED (was 255).
scripts/check-test-counts.sh: OK.
Documentation updates
─────────────────────
* doc/tutorials/add-output-uv-map.md §3.4: "Current limitation: no
chaining" → "Chaining: use the pipe operator `|`". Explains why
CGAL's `.member()` syntax isn't available and shows the `|`
workaround with a working code example.
* doc/architecture/locked-vs-flexible.md §8: chaining now flagged as
shipped via pipe; recommended posture says `.member()` chaining
only if a user pushes for the CGAL-canonical syntax.
* doc/roadmap/porting-status.md §5: API limitations table updated.
* doc/api/tests.md: CGALPhase8bLite row 15 → 17, total 232 → 234.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Tarik Moussa
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eb393537f3 |
docs: 5-document meeting prep — tutorials + research note + status + architecture
External-reviewer-visit prep package (Springborn-Bobenko PhD alumnus,
2026-05-26). All five documents target the same audience: a
mathematician who wants to evaluate, extend, or contribute to
conformallab++. Goal: make the project maximally hackable BEFORE the
meeting. Code unchanged in this commit — pure documentation.
Files added
───────────
1. **doc/tutorials/block-fd-hessian.md** (460 lines)
Step-by-step tutorial on the per-face block-FD Hessian pattern
shipped in Phase 9b (96× speed-up). Matches the style of
add-inversive-distance.md. Covers:
* The per-face locality lemma (mathematical justification).
* Cost analysis (full-FD vs block-FD vs analytic).
* Implementation walkthrough through face_angles_from_local_dofs +
hyper_ideal_hessian_block_fd.
* Porting checklist for applying the same pattern to a new
functional.
* The four cross-validation criteria.
* When NOT to use block-FD + upgrade path to Phase 9b-analytic.
2. **doc/tutorials/add-output-uv-map.md** (477 lines)
Tutorial for the `output_uv_map` named-parameter pattern shipped in
PR #14. Covers:
* The UX problem (two-step pipeline → one-call wrapper).
* The CGAL named-parameter mechanism + how the entry functions
wire it (get_parameter + constexpr if).
* Step-by-step recipe for adding a new named parameter (worked
example: hypothetical `output_holonomy_map`).
* The five test patterns for verification.
* Why CP-Euclidean (face-DOF) and Inversive-Distance (Luo-edge-length)
do not yet support output_uv_map — what is needed to add them.
3. **doc/math/hyperideal-hessian-derivation.md** (805 lines)
Research-quality LaTeX-formatted derivation of the analytic
HyperIdeal Hessian via the Schläfli identity (Phase 9b-analytic
preparation). Covers:
* Schläfli identity (1858/60) — gradient and second-order form.
* Derivatives of ζ, ζ₁₃, ζ₁₄, ζ₁₅ (all hyper-ideal-to-fully-ideal cases).
* Chain rule for ∂β_i/∂(b,a) and ∂α_ij/∂(b,a) — case-split on the
four α_ij branches.
* Per-face 6×6 block formulas.
* Acceptance criteria for the future implementation.
* Implementation outline (Conformal_map header sketch).
* Appendix A: sign / argument-order pitfalls reading the code.
* References: Schläfli 1858, Milnor 1982, Vinberg 1993, Cho-Kim 1999,
Rivin, Glickenstein 2011, Springborn 2020, BPS 2015.
4. **doc/roadmap/porting-status.md** (~250 lines)
Operational snapshot of "where is each piece of Java math today"
at v0.9.0. Sections:
* 25 000 lines of Java in one table (ported / worth porting /
intentionally skipped breakdown).
* Five DCE models — full status matrix with Java port status,
Hessian type, Newton support, CGAL entry, UV-output capability.
* Topology + solver infrastructure status.
* CGAL public API map + known limitations (no chaining, Surface_mesh
only, submission-readiness gaps).
* Reverse cross-reference: Java class → C++ port location (or
"skipped: replaced by …" / "in roadmap: phase X").
* Things in C++ that the Java original does NOT have (research
extensions track).
* "How to use the library today" quickstart.
5. **doc/architecture/locked-vs-flexible.md** (~270 lines)
12-item architecture-decision review with tier classification
(🔴 load-bearing / 🟡 semi-fixed / 🟢 opportunistic). Each item
includes: locked-since date, cost to change, when to revisit,
recommended posture for new contributors. Key insight stated up
front: "the load-bearing decisions are all good in 2026". Closes
with five open questions for the external reviewer — items where
a second opinion would genuinely help (Phase 9c algorithm choice,
Phase 10a priorities, analytic-Hessian payoff justification,
CGAL upstream vs independent distribution, geometry-central
cross-validation).
Total: ~2 250 lines across five new docs.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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