/tmp/B.oxclwyi3/BUILD/SFCGAL-2.3.0-build/SFCGAL-v2.3.0/src/algorithm/surfaceSimplification.h

Simplify a surface mesh using CGAL edge collapse algorithmSimplifies a 3D surface mesh by iteratively collapsing edges while minimizing geometric error. Supports TriangulatedSurface, PolyhedralSurface, Solid, and MultiSolid geometries.

The algorithm uses CGAL's Surface_mesh_simplification package to perform edge collapse operations. The cost and placement of edge collapses are determined by the specified strategy.

Parameters

geometry	The input geometry to simplify (must be a surface or solid)
stopPredicate	When to stop the simplification process
strategy	The cost and placement strategy to use (default: EDGE_LENGTH)

Returns

A simplified copy of the input geometry

Precondition

The input geometry must be valid and non-empty

For EDGE_COUNT_RATIO, the ratio must be in the range (0.0, 1.0)

The geometry must be 3-dimensional

Warning

Surface geometries (polygon soups) will be converted to CGAL::Surface_mesh, which may modify the topology if the input is not manifold

See also

https://doc.cgal.org/latest/Surface_mesh_simplification/index.html#Chapter_Triangulated_Surface_Mesh_Simplification

auto simplified = surfaceSimplification(
    polyhedralSurface,
    SimplificationStopPredicate::edgeCountRatio(0.5),
    SimplificationStrategy::EDGE_LENGTH
);

// Copyright (c) 2025-2026, SFCGAL Team.
// SPDX-License-Identifier: LGPL-2.0-or-later

#ifndef SFCGAL_ALGORITHM_SURFACE_SIMPLIFICATION_H
#define SFCGAL_ALGORITHM_SURFACE_SIMPLIFICATION_H

#include "SFCGAL/Geometry.h"
#include "SFCGAL/config.h"

#include <memory>

namespace SFCGAL::algorithm {
struct NoValidityCheck;

enum class SimplificationStrategy : unsigned char {
  EDGE_LENGTH,

#ifdef SFCGAL_WITH_EIGEN

  GARLAND_HECKBERT,

  LINDSTROM_TURK
#endif // SFCGAL_WITH_EIGEN
};

struct SimplificationStopPredicate {
  enum class PredicateType : unsigned char {
    EDGE_COUNT,

    EDGE_COUNT_RATIO
  };

  PredicateType type;  
  double        value; 

  static auto
  edgeCount(size_t count) -> SimplificationStopPredicate
  {
    return {PredicateType::EDGE_COUNT, static_cast<double>(count)};
  }

  static auto
  edgeCountRatio(double ratio) -> SimplificationStopPredicate
  {
    return {PredicateType::EDGE_COUNT_RATIO, ratio};
  }
};

[[nodiscard]] SFCGAL_API auto
surfaceSimplification(
    const Geometry &geometry, const SimplificationStopPredicate &stopPredicate,
    SimplificationStrategy strategy = SimplificationStrategy::EDGE_LENGTH)
    -> std::unique_ptr<Geometry>;

[[nodiscard]] SFCGAL_API auto
surfaceSimplification(const Geometry                    &geometry,
                      const SimplificationStopPredicate &stopPredicate,
                      SimplificationStrategy strategy, NoValidityCheck noCheck)
    -> std::unique_ptr<Geometry>;

} // namespace SFCGAL::algorithm

#endif // SFCGAL_ALGORITHM_SURFACE_SIMPLIFICATION_H