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Merge pull request #8418 from sloriot/PMP-isorem_deg_faces 

[isotropic_remeshing] do no flip if creating a degenerate face
This commit is contained in:
Laurent Rineau 2024-09-27 10:59:52 +02:00
parent 119bd102c9 eabb4dc756
commit 5a06283647
1 changed files with 21 additions and 24 deletions
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45
Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Isotropic_remeshing/remesh_impl.h
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@ -1704,29 +1704,28 @@ private:
return true;
bool done = false;
while(!degenerate_faces.empty())
{
halfedge_descriptor h = *(degenerate_faces.begin());
degenerate_faces.erase(degenerate_faces.begin());
if (!is_degenerate_triangle_face(face(h, mesh_), mesh_,
parameters::vertex_point_map(vpmap_)
.geom_traits(gt_)))
//this can happen when flipping h has consequences further in the mesh
continue;
//check that opposite is not also degenerate
degenerate_faces.erase(opposite(h, mesh_));
if(is_border(h, mesh_))
if(is_border(opposite(h, mesh_), mesh_))
{
CGAL::Euler::remove_face(h, mesh_);
continue;
}
for(halfedge_descriptor hf :
halfedges_around_face(h, mesh_))
{
if(face(opposite(hf, mesh_), mesh_) == boost::graph_traits<PM>::null_face())
continue;
halfedge_descriptor hfo = opposite(hf, mesh_);
if(is_border(hfo, mesh_))
{
CGAL::Euler::remove_face(h, mesh_);
break;
}
vertex_descriptor vc = target(hf, mesh_);
vertex_descriptor va = target(next(hf, mesh_), mesh_);
vertex_descriptor vb = target(next(next(hf, mesh_), mesh_), mesh_);
@ -1734,7 +1733,6 @@ private:
Vector_3 ac(get(vpmap_,va), get(vpmap_,vc));
if (ab * ac < 0)
{
halfedge_descriptor hfo = opposite(hf, mesh_);
halfedge_descriptor h_ab = prev(hf, mesh_);
halfedge_descriptor h_ca = next(hf, mesh_);
@ -1746,6 +1744,16 @@ private:
if (!is_flip_topologically_allowed(edge(hf, mesh_)))
continue;
// geometric condition for flip --> do not create new degenerate face
vertex_descriptor vd = target(next(hfo, mesh_), mesh_);
if ( collinear( get(vpmap_, va), get(vpmap_, vb), get(vpmap_, vd) ) ||
collinear( get(vpmap_, va), get(vpmap_, vc), get(vpmap_, vd) ) ) continue;
// remove opposite face from the queue (if degenerate)
degenerate_faces.erase(hfo);
degenerate_faces.erase(next(hfo, mesh_));
degenerate_faces.erase(prev(hfo, mesh_));
CGAL::Euler::flip_edge(hf, mesh_);
done = true;
@ -1769,17 +1777,6 @@ private:
short_edges.insert(typename Bimap::value_type(hf, sqlen.value()));
}
if(!is_border(hf, mesh_) &&
is_degenerate_triangle_face(face(hf, mesh_), mesh_,
parameters::vertex_point_map(vpmap_)
.geom_traits(gt_)))
degenerate_faces.insert(hf);
if(!is_border(hfo, mesh_) &&
is_degenerate_triangle_face(face(hfo, mesh_), mesh_,
parameters::vertex_point_map(vpmap_)
.geom_traits(gt_)))
degenerate_faces.insert(hfo);
break;
}
}