Phase 9a-Newton + Phase 8b-Lite: complete the CGAL API surface for all 5 DCE models #11

Merged
user2595 merged 2 commits from feature/phase-9a-newton into main 2026-05-21 20:15:50 +00:00

2 Commits

Author SHA1 Message Date
Tarik Moussa
7d10500811 Phase 8b-Lite: CGAL entries for all 5 DCE models + layout wrapper
Some checks failed
C++ Tests / test-fast (pull_request) Successful in 2m7s
C++ Tests / test-fast (push) Successful in 2m19s
C++ Tests / test-cgal (pull_request) Failing after 11m6s
C++ Tests / test-cgal (push) Has been skipped
API Docs / doc-build (pull_request) Successful in 41s
Completes the CGAL public API surface so all five discrete-conformal
functionals are reachable from <CGAL/Discrete_*.h>, not only Euclidean.

CGAL test count: 219 → 227 (+8).  Zero skips.

New public headers
──────────────────
* CGAL/Discrete_conformal_map.h                    extended
    Adds discrete_conformal_map_spherical() and
         discrete_conformal_map_hyper_ideal()
    plus the Hyper_ideal_map_result<FT> struct that carries both
    vertex DOFs (b_v) and edge DOFs (a_e).

* CGAL/Discrete_circle_packing.h                   new (180 lines)
    Face-based BPS-2010 circle packing.  Provides
         Default_cp_euclidean_traits<Mesh, K>
         Circle_packing_result<FT>
         discrete_circle_packing_euclidean()

* CGAL/Discrete_inversive_distance.h               new (180 lines)
    Vertex-based Luo-2004 packing.  Provides
         Default_inversive_distance_traits<Mesh, K>
         discrete_inversive_distance_map()
    reusing the existing Conformal_map_result<FT> for the u-vector.

* CGAL/Conformal_layout.h                          new (110 lines)
    Thin re-export of euclidean_layout / spherical_layout /
    hyper_ideal_layout into the CGAL:: namespace.

Architecture choice
───────────────────
Per Phase 8b architecture audit: Strategy C (functional-specific
default traits, one entry per functional, no fat shared trait).
Documented in each header's docblock.  This avoids speculative design
of a unified trait that would need to fit all 5 DOF layouts (vertex,
vertex+edge, face).

Conformal_map_traits.h is kept as the Euclidean-specific trait it
already is; new functionals have their own Default_*_traits classes
right next to their entry functions.

Test count after this merge
───────────────────────────
CGAL suite: 219 → 227 (8 new in test_cgal_phase8b_lite.cpp covering
all four new entries + the Euclidean+layout round-trip).

After-the-merge user contract
─────────────────────────────
A user can now write any of these and get a valid Newton-converged result:

  #include <CGAL/Discrete_conformal_map.h>
  auto r = CGAL::discrete_conformal_map_euclidean(mesh);
  auto r = CGAL::discrete_conformal_map_spherical(mesh);
  auto r = CGAL::discrete_conformal_map_hyper_ideal(mesh);

  #include <CGAL/Discrete_circle_packing.h>
  auto r = CGAL::discrete_circle_packing_euclidean(mesh);

  #include <CGAL/Discrete_inversive_distance.h>
  auto r = CGAL::discrete_inversive_distance_map(mesh);

  #include <CGAL/Conformal_layout.h>
  auto layout = CGAL::euclidean_layout(mesh, r.x, maps);

Not in this PR (intentionally deferred)
───────────────────────────────────────
* 8a.2 — Generic FaceGraph specialisation (still Surface_mesh-only).
* 8c   — User_manual + PackageDescription.txt (CGAL-submission prep).
* 8d   — CGAL-format test directory  (CGAL-submission prep).
* 8e   — YAML pipeline + CLI flag    (orthogonal).
* Named-parameter chaining (`a.b().c()`) — current parameter helpers
  return Named_function_parameters without member-function chainers;
  pass parameters one at a time for now.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-21 21:24:26 +02:00
Tarik Moussa
dd87b8007b Phase 9a-Newton: newton_cp_euclidean + newton_inversive_distance
Some checks failed
C++ Tests / test-fast (push) Has been cancelled
C++ Tests / test-cgal (push) Has been cancelled
C++ Tests / test-fast (pull_request) Successful in 2m28s
API Docs / doc-build (pull_request) Successful in 52s
C++ Tests / test-cgal (pull_request) Failing after 11m29s
Wires the two Phase-9a functionals into the Newton-solver layer so
they are operational end-to-end.  CGAL test count: 212 → 219 (+7).

Solvers
───────
* newton_cp_euclidean(mesh, x0, m, tol, max_iter)
    - Uses cp_euclidean_hessian — analytic 2×2-per-edge BPS-2010
      formula h_jk = sin θ / (cosh Δρ − cos θ).
    - SparseQR fallback handles the gauge-singular case when no face
      is pinned (caller error, but we recover gracefully).
    - Strictly-convex energy ⇒ quadratic convergence near optimum.

* newton_inversive_distance(mesh, x0, m, tol, max_iter, hess_eps)
    - Uses an inline FD Hessian (n × gradient evaluations per step) —
      mirrors the Phase 4a HyperIdeal solver in spirit.
    - Analytic alternative via Glickenstein 2011 eq. (4.6) is tracked
      in doc/roadmap/research-track.md as Phase 9a.2-analytic.
    - Sensitive to initial point; the test suite always starts from
      a natural-theta setup (u = 0 is the equilibrium when
      compute_inversive_distance_init_from_mesh was called).

Tests (test_newton_phase9a.cpp, 7 cases)
────────────────────────────────────────
* CPEuclidean_NaturalPhi_ClosedTetrahedron_ConvergesInZeroIterations
* CPEuclidean_PerturbedStart_ConvergesBackToEquilibrium
* CPEuclidean_OpenTetrahedron_NaturalPhi_Converges
* InversiveDistance_NaturalTheta_Triangle_ConvergesInZero
* InversiveDistance_PerturbedQuadStrip_Converges
* InversiveDistance_PerturbedTetrahedron_Converges
* CPEuclidean_UsesAnalyticHessian
    Regression guard: 3-DOF problem converges in ≤ 10 iterations even
    with strong perturbation, confirming the analytic Hessian path is
    actually used.

All seven tests pass.  Full CGAL suite: 219/219 PASSED, 0 SKIPPED.

Roadmap additions (`doc/roadmap/phases.md`)
───────────────────────────────────────────
New Phase 11+ section flags two Java sub-packages as optional/deferred
ports, recorded for project memory but not roadmap commitments:

* 11a — Schottky uniformisation (Java plugin/schottky/*, ~3000 LoC)
        Hyperbolic loxodromic group acting on S²; complement of the
        Phase 10c Fuchsian-group representation in H².  Requires
        Phase 10b period matrix + Möbius-group machinery from Phase 7.
        Effort: very large (4-6 weeks).

* 11b — Riemann maps (Java plugin/riemannmap/*, ~1500 LoC)
        Discrete Riemann mapping theorem; texture mapping of bounded
        planar regions, classical conformal mapping for engineering.
        Requires Phase 10b' quasi-isothermic or Phase 9a.1 CP-Euclidean.
        Effort: large (3-4 weeks).

Both are explicitly NOT roadmap commitments — they live in the doc so
they aren't re-discovered.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-21 21:10:00 +02:00