ConformalLabpp/code/tests/cgal/test_cgal_phase8b_lite.cpp

// test_cgal_phase8b_lite.cpp
//
// Phase 8b-Lite — Smoke tests for the four new CGAL-style entry functions
// added on top of the Phase 8a MVP (`discrete_conformal_map_euclidean`).
//
// All entries are thin wrappers around the legacy Newton solvers; the
// purpose of these tests is to verify:
//   • the wrapper compiles + dispatches correctly
//   • named parameters pass through (gradient_tolerance, max_iterations)
//   • the returned Result struct contains the expected DOF vector
//   • Newton convergence happens end-to-end via the public API

#include <CGAL/Discrete_conformal_map.h>
#include <CGAL/Discrete_circle_packing.h>
#include <CGAL/Discrete_inversive_distance.h>
#include <CGAL/Conformal_layout.h>

#include "mesh_builder.hpp"
#include "conformal_mesh.hpp"

#include <gtest/gtest.h>
#include <cmath>

using namespace conformallab;

namespace {

// Mesh helper — closed regular tetrahedron, used for spherical / hyper-ideal /
// circle-packing tests.
inline ConformalMesh make_closed_tet() { return make_tetrahedron(); }

// Open 3-face tetrahedron-minus-face, for layout testing.
inline ConformalMesh make_open_3face()
{
    ConformalMesh mesh;
    auto v0 = mesh.add_vertex(Point3( 1,  1,  1));
    auto v1 = mesh.add_vertex(Point3( 1, -1, -1));
    auto v2 = mesh.add_vertex(Point3(-1,  1, -1));
    auto v3 = mesh.add_vertex(Point3(-1, -1,  1));
    mesh.add_face(v0, v2, v1);
    mesh.add_face(v0, v1, v3);
    mesh.add_face(v0, v3, v2);
    return mesh;
}

} // anonymous

// ════════════════════════════════════════════════════════════════════════════
// 1.  Spherical entry — closed genus-0 tetrahedron, natural-theta default
// ════════════════════════════════════════════════════════════════════════════

TEST(CGALPhase8bLite, Spherical_ClosedTetrahedron_NaturalThetaConverges)
{
    auto mesh = make_closed_tet();
    auto res  = CGAL::discrete_conformal_map_spherical(mesh);

    EXPECT_TRUE(res.converged);
    EXPECT_LT(res.gradient_norm, 1e-8);
    EXPECT_EQ(res.u_per_vertex.size(), num_vertices(mesh));
    // Natural-theta ⇒ u = 0 is the equilibrium ⇒ all values ≈ 0.
    for (double u : res.u_per_vertex) EXPECT_NEAR(u, 0.0, 1e-8);
}

TEST(CGALPhase8bLite, Spherical_NamedParametersTakeEffect)
{
    auto mesh = make_closed_tet();
    auto res  = CGAL::discrete_conformal_map_spherical(
        mesh,
        CGAL::parameters::max_iterations(0));
    EXPECT_EQ(res.iterations, 0);
}

// ════════════════════════════════════════════════════════════════════════════
// 2.  Hyper-ideal entry — wrapper compiles + runs, returns both b_v and a_e
// ════════════════════════════════════════════════════════════════════════════

TEST(CGALPhase8bLite, HyperIdeal_Tetrahedron_ReturnsBothVertexAndEdgeDOFs)
{
    auto mesh = make_closed_tet();
    auto res  = CGAL::discrete_conformal_map_hyper_ideal(
        mesh,
        CGAL::parameters::max_iterations(20));

    // Newton on default targets (Θ=2π, θ=π) from the "natural" b=1, a=0.5
    // start may or may not converge in 20 iterations — but the wrapper must
    // populate the result struct in any case.
    EXPECT_EQ(res.b_per_vertex.size(), num_vertices(mesh));
    EXPECT_EQ(res.a_per_edge.size(),    num_edges   (mesh));
    EXPECT_GE(res.iterations, 0);
    EXPECT_TRUE(std::isfinite(res.gradient_norm));
}

// ════════════════════════════════════════════════════════════════════════════
// 3.  Circle-packing (face-based) entry — natural-phi convergence
// ════════════════════════════════════════════════════════════════════════════

TEST(CGALPhase8bLite, CirclePacking_ClosedTetrahedron_NaturalPhiConverges)
{
    auto mesh = make_closed_tet();
    auto res  = CGAL::discrete_circle_packing_euclidean(mesh);

    EXPECT_TRUE(res.converged);
    EXPECT_LT(res.gradient_norm, 1e-8);
    EXPECT_EQ(res.rho_per_face.size(), num_faces(mesh));
    // Pinned face is at index 0 (first iterated face); its ρ is 0 by gauge.
    // After natural-phi the equilibrium is ρ_f = 0 for every face.
    for (double r : res.rho_per_face) EXPECT_NEAR(r, 0.0, 1e-8);
}

TEST(CGALPhase8bLite, CirclePacking_GradientToleranceTakesEffect)
{
    auto mesh = make_closed_tet();
    auto res_loose = CGAL::discrete_circle_packing_euclidean(
        mesh,
        CGAL::parameters::gradient_tolerance(1e-4));
    EXPECT_TRUE(res_loose.converged);

    auto mesh2 = make_closed_tet();
    auto res_strict = CGAL::discrete_circle_packing_euclidean(
        mesh2,
        CGAL::parameters::gradient_tolerance(1e-12));
    EXPECT_TRUE(res_strict.converged);
    EXPECT_LT(res_strict.gradient_norm, 1e-10);
}

// ════════════════════════════════════════════════════════════════════════════
// 4.  Inversive-distance (vertex-based) entry — natural-theta convergence
// ════════════════════════════════════════════════════════════════════════════

TEST(CGALPhase8bLite, InversiveDistance_Triangle_NaturalThetaConverges)
{
    auto mesh = make_triangle();
    auto res  = CGAL::discrete_inversive_distance_map(mesh);

    EXPECT_TRUE(res.converged);
    EXPECT_LT(res.gradient_norm, 1e-8);
    EXPECT_EQ(res.u_per_vertex.size(), num_vertices(mesh));
    for (double u : res.u_per_vertex) EXPECT_NEAR(u, 0.0, 1e-8);
}

TEST(CGALPhase8bLite, InversiveDistance_QuadStrip_NamedParametersWork)
{
    auto mesh = make_quad_strip();
    // Named-parameter chaining (`a.b().c()`) is not currently supported on
    // the package-local tags; pass one parameter per call instead.
    auto res  = CGAL::discrete_inversive_distance_map(
        mesh,
        CGAL::parameters::max_iterations(50));
    EXPECT_TRUE(res.converged);
    EXPECT_LE(res.iterations, 50);
}

// ════════════════════════════════════════════════════════════════════════════
// 5.  Layout wrapper — end-to-end through CGAL API on an open mesh
//
// Uses the legacy maps explicitly because the wrappers return the
// Newton-converged x vector but not the maps.  This exercises that the
// `CGAL::euclidean_layout` shim works as expected.
// ════════════════════════════════════════════════════════════════════════════

TEST(CGALPhase8bLite, Layout_EuclideanWrapper_RoundTrip)
{
    auto mesh = make_open_3face();

    // Set up the maps + run Newton via the CGAL Euclidean entry.
    auto res  = CGAL::discrete_conformal_map_euclidean(mesh);
    ASSERT_TRUE(res.converged);

    // The wrapper does its own DOF assignment internally; we re-fetch
    // the (now-populated) EuclideanMaps from the mesh's property maps
    // to feed the layout wrapper.
    auto maps = setup_euclidean_maps(mesh);
    compute_euclidean_lambda0_from_mesh(mesh, maps);
    // Pin first vertex (mirrors the wrapper's gauge choice).
    auto vit = mesh.vertices().begin();
    maps.v_idx[*vit++] = -1;
    int idx = 0;
    for (; vit != mesh.vertices().end(); ++vit) maps.v_idx[*vit] = idx++;
    std::vector<double> x(idx, 0.0);   // wrapper's natural-theta equilibrium

    auto layout = CGAL::euclidean_layout(mesh, x, maps);
    EXPECT_EQ(layout.uv.size(), num_vertices(mesh));
    // All UVs finite — basic sanity that the layout ran.
    for (auto& uv : layout.uv) {
        EXPECT_TRUE(std::isfinite(uv.x()));
        EXPECT_TRUE(std::isfinite(uv.y()));
    }
}