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Add mollification step to avoid degenerate faces #5037

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merged 10 commits into from
Apr 6, 2021
Merged

Add mollification step to avoid degenerate faces #5037

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005f237
Add mollification step to avoid degenerate faces
oboes Sep 29, 2020
6aa3d6d
Update Heat_method_3/include/CGAL/Heat_method_3/internal/Intrinsic_De…
oboes Oct 5, 2020
7346b93
Merge branch 'Demo-Fix_ssh-maxGimeno' into Heat_method_3-mollify-oboes
janetournois Nov 13, 2020
2df9424
Merge remote-tracking branch 'cgal/master' into Heat_method_3-mollify…
janetournois Nov 13, 2020
a8a1b2d
degenerate faces are allowed with Intrinsic_Delaunay Mode
janetournois Nov 13, 2020
14cc871
with mollification degenerate faces are allowed with Mode=Intrinsic_D…
janetournois Nov 20, 2020
bc18b7d
add a test for Intrinsic_Delaunay Mode with an input with degenerate …
janetournois Nov 20, 2020
f2f10e7
add missing namespace
janetournois Nov 20, 2020
40197ad
add missing forward declaration
janetournois Dec 8, 2020
1448c65
Merge remote-tracking branch 'cgal/master' into Heat_method_3-mollify…
janetournois Mar 22, 2021
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26 changes: 26 additions & 0 deletions Heat_method_3/include/CGAL/Heat_method_3/internal/Intrinsic_Delaunay_triangulation_3.h
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Original file line number Diff line number Diff line change
Expand Up @@ -285,6 +285,29 @@ class Intrinsic_Delaunay_triangulation_3
return CGAL::sqrt(S*(S-a)*(S-b)*(S-c));
}

// Mollification strategy to avoid degeneracies
void
mollify(double delta)
{
// compute smallest length epsilon we can add to
// all edges to ensure that the strict triangle
// inequality holds with a tolerance of delta
double epsilon = 0;
for(halfedge_descriptor hd : halfedges(m_intrinsic_tm)) {
halfedge_descriptor hd2 = next(hd, m_intrinsic_tm);
halfedge_descriptor hd3 = next(hd2,m_intrinsic_tm);
Index i = get(edge_id_map, edge(hd,m_intrinsic_tm));
Index j = get(edge_id_map, edge(hd2,m_intrinsic_tm));
Index k = get(edge_id_map, edge(hd3,m_intrinsic_tm));
double ineq = edge_lengths[j] + edge_lengths[k] - edge_lengths[i];
epsilon = std::max(epsilon, std::max(0., delta-ineq));
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}
// update edge lengths
for(edge_descriptor ed : edges(m_intrinsic_tm)) {
Index i = get(edge_id_map, ed);
edge_lengths[i] += epsilon;
}
}

void
loop_over_edges(edge_stack stack, std::vector<int>& marked_edges)
Expand Down Expand Up @@ -365,13 +388,16 @@ class Intrinsic_Delaunay_triangulation_3
Index edge_i = 0;
VertexPointMap vpm_intrinsic_tm = get(boost::vertex_point,m_intrinsic_tm);

double min_length = (std::numeric_limits<double>::max)();
for(edge_descriptor ed : edges(m_intrinsic_tm)) {
edge_lengths[edge_i] = CGAL::sqrt(to_double(squared_distance(get(vpm_intrinsic_tm, source(ed,m_intrinsic_tm)),
get(vpm_intrinsic_tm, target(ed,m_intrinsic_tm)))));
// Polygon_mesh_processing::edge_length(halfedge(ed,m_intrinsic_tm),m_intrinsic_tm);
if (edge_lengths[edge_i] != 0 && edge_lengths[edge_i] < min_length) min_length = edge_lengths[edge_i];
put(edge_id_map, ed, edge_i++);
stack.push(ed);
}
mollify(min_length*1e-4);
loop_over_edges(stack, mark_edges);
//now that edges are calculated, go through and for each face, calculate the vertex positions around it

Expand Down