CGAL users discussion list

[Kim <>]

Hi everyone,

I am using make_mesh_3 to mesh an implicit domain and subsequently
extracting the surface triangulation, clipping it and doing some other
post-processing. 

typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef CGAL::Parallel_tag Concurrency_tag;
typedef CGAL::Polyhedron_3<Kernel, CGAL::Polyhedron_items_with_id_3>
PolygonMesh;
typedef CGAL::Labeled_mesh_domain_3<Kernel> Implicit_domain;
typedef CGAL::Mesh_triangulation_3<Implicit_domain, CGAL::Default,
Concurrency_tag>::type VTr;
typedef CGAL::Mesh_complex_3_in_triangulation_3<VTr> C3t3;
typedef CGAL::Mesh_criteria_3<VTr> Mesh_criteria;

Implicit_domain domain = Implicit_domain::create_implicit_mesh_domain(
    myImplicitFunction, boundBox);

Mesh_criteria criteria(CGAL::parameters::facet_angle = facetAngle,
    CGAL::parameters::facet_size = facetSize,
    CGAL::parameters::facet_distance = facetDistance);

C3t3 c3t3 = CGAL::make_mesh_3<C3t3>(domain, criteria,
CGAL::parameters::manifold())

PolygonMesh scaffold;
CGAL::facets_in_complex_3_to_triangle_mesh(c3t3, scaffold);

// Clip mesh
PolygonMesh outer_shell;
CGAL::Polygon_mesh_processing::polygon_soup_to_polygon_mesh(points,
polygons, outer_shell);

CGAL::Polygon_mesh_processing::remove_isolated_vertices(scaffold); //
Temporary fix to bug!!!
if( CGAL::Polygon_mesh_processing::clip(scaffold, outer_shell,
CGAL::parameters::clip_volume(true).use_compact_clipper(true)) == false)
    std::cout << "\n WARNING: Scaffold and clipper have only been
corefined!" << std::endl;

// Remove all but the largest component
CGAL::Polygon_mesh_processing::keep_largest_connected_components(scaffold,
1);

// Reorient all faces coherently
if (CGAL::is_closed(scaffold) == true) {
    CGAL::Polygon_mesh_processing::orient(scaffold,
CGAL::parameters::outward_orientation(true));
} else {
    std::cout << "\n WARNING: Polygon has border edges!" << std::endl;
}

The problem I am experiencing is that although I have specified I want a
manifold mesh make_mesh_3 does not seem to always output one. Some inputs
seem to always result in a non-manifold mesh while others may result in a
non-manifold mesh occasionally without any change in inputs. I get the same
behavior regardless of whether I use mesh optimizations or disable them. Am
I doing something incorrectly?

Kind regards,
Kim



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