# conformallab++

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[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)
[![DOI](https://img.shields.io/badge/doi-Sechelmann%202016-blue)](https://depositonce.tu-berlin.de/items/8e2988b2-d991-45b5-aad5-9fb7988f3b2f)

C++17 reimplementation of [ConformalLab](https://github.com/varylab/conformallab) —
Stefan Sechelmann's Java research library for discrete conformal geometry (TU Berlin).
The long-term goal is a **CGAL package** for discrete conformal maps.

Algorithmic foundation:
> Stefan Sechelmann — *Variational Methods for Discrete Surface Parameterization: Applications and Implementation*, TU Berlin 2016.
> DOI: [10.14279/depositonce-5415](https://depositonce.tu-berlin.de/items/8e2988b2-d991-45b5-aad5-9fb7988f3b2f) · CC BY-SA 4.0 ·
> [Java original](https://github.com/varylab/conformallab) · [sechel.de](https://sechel.de/)

**Status:** v0.9.0 — Phases 1–9a complete, Phase 8b-Lite CGAL API surface. Newton solvers for **five** DCE models (Euclidean / Spherical / HyperIdeal / CP-Euclidean / Inversive-Distance), priority-BFS layout in ℝ²/S²/Poincaré disk, Gauss–Bonnet, tree-cotree cut graph, Möbius holonomy, period matrix (genus 1), fundamental domain, halfedge_uv texture atlas, JSON/XML serialisation, CLI app.  Full test suite passing, 0 skipped — see [`doc/api/tests.md`](doc/api/tests.md) for the per-suite breakdown.

---

## Quick start

```bash
git clone https://codeberg.org/TMoussa/ConformalLabpp && cd ConformalLabpp

# Fast tests — no system dependencies
cmake -S code -B build && cmake --build build --target conformallab_tests -j$(nproc)
ctest --test-dir build --output-on-failure

# CGAL tests headless (apt install libboost-dev / brew install boost)
cmake -S code -B build -DWITH_CGAL_TESTS=ON
cmake --build build --target conformallab_cgal_tests -j$(nproc)
ctest --test-dir build -R "^cgal\." --output-on-failure

# Full build with CLI + viewer (requires Wayland/X11 dev headers)
cmake -S code -B build -DWITH_CGAL=ON && cmake --build build -j$(nproc)
./bin/conformallab_core -i input.off -g euclidean -o layout.off -j result.json

# API documentation (requires doxygen: brew/apt install doxygen)
cmake --build build --target doc
open doc/doxygen/html/index.html
```

---

## Minimal usage

```cpp
#include "conformal_mesh.hpp"
#include "mesh_io.hpp"
#include "euclidean_functional.hpp"
#include "gauss_bonnet.hpp"
#include "newton_solver.hpp"
#include "layout.hpp"

using namespace conformallab;

ConformalMesh mesh = load_mesh("input.off");
EuclideanMaps maps = setup_euclidean_maps(mesh);
compute_euclidean_lambda0_from_mesh(mesh, maps);

// Assign DOFs — pin first vertex (gauge fix)
auto vit = mesh.vertices().begin();
maps.v_idx[*vit++] = -1;
int idx = 0;
for (; vit != mesh.vertices().end(); ++vit) maps.v_idx[*vit] = idx++;

// Natural equilibrium target: x* = 0 by construction
std::vector<double> x0(idx, 0.0);
auto G0 = euclidean_gradient(mesh, x0, maps);
for (auto v : mesh.vertices())
    if (maps.v_idx[v] >= 0) maps.theta_v[v] -= G0[maps.v_idx[v]];

check_gauss_bonnet(mesh, maps);
NewtonResult res = newton_euclidean(mesh, x0, maps);
Layout2D layout = euclidean_layout(mesh, res.x, maps);
```

---

## Documentation

| | |
|---|---|
| **Getting started** — build modes, single-test invocation, CLI, Docker | [doc/getting-started.md](doc/getting-started.md) |
| **Pipeline API** — all three geometries, holonomy, serialisation | [doc/api/pipeline.md](doc/api/pipeline.md) |
| **Public headers** — all 24 headers with descriptions | [doc/api/headers.md](doc/api/headers.md) |
| **Test suites** — per-suite breakdown and counts (single source of truth) | [doc/api/tests.md](doc/api/tests.md) |
| **Extending** — new functionals, geometry modes, porting from Java | [doc/api/extending.md](doc/api/extending.md) |
| **Processing unit contracts** — preconditions / provides table | [doc/api/contracts.md](doc/api/contracts.md) |
| **CGAL package design** — Phase 8 target, YAML pipeline | [doc/api/cgal-package.md](doc/api/cgal-package.md) |
| **Architecture & pipeline diagram** | [doc/architecture/overall_pipeline.md](doc/architecture/overall_pipeline.md) |
| **geometry-central comparison** — shared core, demarcation, adoption candidates, scientific added value | [doc/architecture/geometry-central-comparison.md](doc/architecture/geometry-central-comparison.md) |
| **Design decisions** — key architectural choices + rationale | [doc/architecture/design-decisions.md](doc/architecture/design-decisions.md) |
| **Project structure** — directory tree + build targets | [doc/architecture/project-structure.md](doc/architecture/project-structure.md) |
| **Discrete conformal theory** — mathematical background for collaborators | [doc/math/discrete-conformal-theory.md](doc/math/discrete-conformal-theory.md) |
| **Validation** — known analytic results + how to verify them | [doc/math/validation.md](doc/math/validation.md) |
| **Validation protocol** — concrete commands with expected outputs | [doc/math/validation-protocol.md](doc/math/validation-protocol.md) |
| **Tutorial: add a new functional** — step-by-step Inversive-Distance port | [doc/tutorials/add-inversive-distance.md](doc/tutorials/add-inversive-distance.md) |
| **Declarative YAML pipeline** — concept, token vocabulary, 5 examples | [doc/concepts/declarative-pipeline.md](doc/concepts/declarative-pipeline.md) |
| **Geometry modes** — Euclidean / Spherical / HyperIdeal comparison | [doc/math/geometry-modes.md](doc/math/geometry-modes.md) |
| **References** — all papers by module | [doc/math/references.md](doc/math/references.md) |
| **Software landscape** — how conformallab++ relates to libigl, CGAL, geometry-central | [doc/math/software-landscape.md](doc/math/software-landscape.md) |
| **Novelty statement** — unique features, target audience, what this is not | [doc/math/novelty-statement.md](doc/math/novelty-statement.md) |
| **Complexity & scalability** — O() analysis, measured timings on real meshes, HyperIdeal bottleneck | [doc/math/complexity.md](doc/math/complexity.md) |
| **Roadmap** — Phases 1–10 | [doc/roadmap/phases.md](doc/roadmap/phases.md) |
| **Java parity table** — what is ported, what is planned | [doc/roadmap/java-parity.md](doc/roadmap/java-parity.md) |
| **Contributing** — language policy, test standards, release flow | [doc/contributing.md](doc/contributing.md) |
| **Claude Code context** | [CLAUDE.md](CLAUDE.md) |

---

## Citing

If you use conformallab++ in your research, please cite it using the metadata
in [`CITATION.cff`](CITATION.cff).  GitHub and Codeberg show a "Cite this repository"
button that generates BibTeX and APA automatically.

The primary algorithmic source is:

> Stefan Sechelmann — *Variational Methods for Discrete Surface Parameterization:
> Applications and Implementation*, TU Berlin 2016.
> DOI: [10.14279/depositonce-5415](https://depositonce.tu-berlin.de/items/8e2988b2-d991-45b5-aad5-9fb7988f3b2f)

---

## Bugs & questions

- **Bug reports / feature requests:** [Gitea Issues](https://git.eulernest.eu/conformallab/ConformalLabpp/issues)
- **Code mirror (read-only):** [Codeberg](https://codeberg.org/TMoussa/ConformalLabpp)
- **Contact:** Tarik Moussa · Tarik.moussa95@gmail.com

---

## License

conformallab++ is released under the MIT License (see [LICENSE](LICENSE)).  
Copyright © 2024–2026 Tarik Moussa.  
The dissertation (Sechelmann 2016) is CC BY-SA 4.0.