cgal.h

#ifndef CGAL_H
#define CGAL_H

// This file contains CGAL routines for decimating meshes,
// most of them adapted from CGAL's example
// Surface_Mesh_Simplification/edge_collapse_enriched_polyhedron.cpp
//   - decimate_CGAL

// *Leo*: I wasn't able to move all these headers to
// cgal.cpp, so I kept as it is.

// BEGIN of CGAL includes
#include <fstream>
#include <CGAL/Simple_cartesian.h>
#include <CGAL/Polyhedron_3.h>
#include <CGAL/IO/Polyhedron_iostream.h>
// Adaptor for Polyhedron_3
#include <CGAL/Surface_mesh_simplification/HalfedgeGraph_Polyhedron_3.h>
// Simplification function
#include <CGAL/Surface_mesh_simplification/edge_collapse.h>
// Visitor base
#include <CGAL/Surface_mesh_simplification/Edge_collapse_visitor_base.h>
// Extended polyhedron items which include an id() field
#include <CGAL/Polyhedron_items_with_id_3.h>
// Stop-condition policy
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Count_ratio_stop_predicate.h>
// Non-default cost and placement policies
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Midpoint_and_length.h> 
typedef CGAL::Simple_cartesian<double> Kernel;
typedef Kernel::Point_3 Point_CGAL ;
typedef CGAL::Polyhedron_3<Kernel,CGAL::Polyhedron_items_with_id_3> Surface_mesh; 
typedef Surface_mesh::Halfedge_handle Halfedge_handle ;
typedef Surface_mesh::Vertex_handle   Vertex_handle ;
namespace SMS = CGAL::Surface_mesh_simplification ;
typedef SMS::Edge_profile<Surface_mesh> Profile ;   
// END of CGAL includes

// The following is a Visitor that keeps track of the simplification process.
// In this example the progress is printed real-time and a few statistics are
// recorded (and printed in the end).
//
struct Stats
{
  Stats() 
    : collected(0)
    , processed(0)
    , collapsed(0)
    , non_collapsable(0)
    , cost_uncomputable(0) 
    , placement_uncomputable(0) 
  {} 
  
  std::size_t collected ;
  std::size_t processed ;
  std::size_t collapsed ;
  std::size_t non_collapsable ;
  std::size_t cost_uncomputable  ;
  std::size_t placement_uncomputable ; 
} ;

struct My_visitor : SMS::Edge_collapse_visitor_base<Surface_mesh>
{
  My_visitor( Stats* s) : stats(s){} 

  // Called during the collecting phase for each edge collected.
  void OnCollected( Profile const&, boost::optional<double> const& )
  {
    ++ stats->collected ;
    // std::cerr << "\rEdges collected: " << stats->collected << std::flush ;
  }                
  
  // Called during the processing phase for each edge selected.
  // If cost is absent the edge won't be collapsed.
  void OnSelected(Profile const&          
                 ,boost::optional<double> cost
                 ,std::size_t             initial
                 ,std::size_t             current
                 )
  {
    ++ stats->processed ;
    if ( !cost )
      ++ stats->cost_uncomputable ;
  }                
  
  // Called during the processing phase for each edge being collapsed.
  // If placement is absent the edge is left uncollapsed.
  void OnCollapsing(Profile const&          
                   ,boost::optional<Point_CGAL>  placement
                   )
  {
    if ( !placement )
      ++ stats->placement_uncomputable ;
  }                
  
  // Called for each edge which failed the so called link-condition,
  // that is, which cannot be collapsed because doing so would
  // turn the surface mesh into a non-manifold.
  void OnNonCollapsable( Profile const& )
  {
    ++ stats->non_collapsable;
  }                
  
  // Called AFTER each edge has been collapsed
  void OnCollapsed( Profile const&, Vertex_handle )
  {
    ++ stats->collapsed;
  }                
  
  Stats* stats ;
} ;


// computes (overlapping) decimations using CGAL's routines
//
// Inputs:
//   surface_mesh  Pointer to the input mesh in Surface_mesh CGAL's format
//   ratio  percentage of faces of the decimated mesh compared to original
//   adaptive  true for adaptive decimation, false for regular
// Output:
//   surface_mesh   Decimated mesh (overwrites input)
void decimate_CGAL(
  Surface_mesh* surface_mesh, 
  const float ratio, 
  const bool adpative);

#endif