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Merge pull request #8129 from sloriot/PMP-deterministic_triangulate_f…
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Make triangulate_faces deterministic
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@lrineau
lrineau committed Apr 22, 2024
2 parents a391e06 + cfec3bb commit 3e3eed7
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Showing 3 changed files with 88 additions and 35 deletions.
93 changes: 73 additions & 20 deletions Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/triangulate_faces.h
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Original file line number Diff line number Diff line change
Expand Up @@ -196,15 +196,15 @@ class Triangulate_polygon_mesh_modifier

if(original_size == 4)
{
halfedge_descriptor v0, v1, v2, v3;
v0 = halfedge(f, pmesh);
Point_ref p0 = get(vpm, target(v0, pmesh));
v1 = next(v0, pmesh);
Point_ref p1 = get(vpm, target(v1, pmesh));
v2 = next(v1, pmesh);
Point_ref p2 = get(vpm, target(v2, pmesh));
v3 = next(v2, pmesh);
Point_ref p3 = get(vpm, target(v3, pmesh));
std::array<halfedge_descriptor,4> verts;
verts[0] = halfedge(f, pmesh);
verts[1] = next(verts[0], pmesh);
verts[2] = next(verts[1], pmesh);
verts[3] = next(verts[2], pmesh);
Point_ref p0 = get(vpm, target(verts[0], pmesh));
Point_ref p1 = get(vpm, target(verts[1], pmesh));
Point_ref p2 = get(vpm, target(verts[2], pmesh));
Point_ref p3 = get(vpm, target(verts[3], pmesh));

/* Chooses the diagonal that will split the quad in two triangles that maximize
* the scalar product of the un-normalized normals of the two triangles.
Expand All @@ -217,10 +217,33 @@ class Triangulate_polygon_mesh_modifier
*/
visitor.before_subface_creations(f);

const FT p1p3 = cross_product(p2-p1, p3-p2) * cross_product(p0-p3, p1-p0);
const FT p0p2 = cross_product(p1-p0, p1-p2) * cross_product(p3-p2, p3-p0);
halfedge_descriptor res = (p0p2>p1p3) ? CGAL::Euler::split_face(v0, v2, pmesh)
: CGAL::Euler::split_face(v1, v3, pmesh);
typename Traits::Vector_3 p0p1=p1-p0;
typename Traits::Vector_3 p1p2=p2-p1;
typename Traits::Vector_3 p2p3=p3-p2;
typename Traits::Vector_3 p0p3=p3-p0;

const FT delta1 = cross_product(p1p2, p2p3) * cross_product(-p0p3, p0p1);
const FT delta2 = cross_product(p0p1, -p1p2) * cross_product(p2p3, p0p3);

halfedge_descriptor res = boost::graph_traits<PolygonMesh>::null_halfedge();

if (delta1!=delta2)
res = (delta2>delta1)
? CGAL::Euler::split_face(verts[0], verts[2], pmesh)
: CGAL::Euler::split_face(verts[1], verts[3], pmesh);
else
{
halfedge_descriptor m =
*(std::min_element)(verts.begin(), verts.end(),
[&pmesh,vpm](halfedge_descriptor v0, halfedge_descriptor v1)
{
return lexicographically_xyz_smaller(get(vpm, target(v0, pmesh)),
get(vpm, target(v1, pmesh)));
});
res = (m==verts[0] || m==verts[2])
? CGAL::Euler::split_face(verts[0], verts[2], pmesh)
: CGAL::Euler::split_face(verts[1], verts[3], pmesh);
}

visitor.after_subface_created(face(res, pmesh));
visitor.after_subface_created(face(opposite(res, pmesh), pmesh));
Expand Down Expand Up @@ -526,6 +549,7 @@ class Triangulate_polygon_soup_modifier
NamedParameters,
Def_Kernel>::type;
using FT = typename Traits::FT;
using PID = typename std::iterator_traits<typename Polygon::const_iterator>::value_type;

// Visitor
using Visitor = typename internal_np::Lookup_named_param_def<
Expand Down Expand Up @@ -564,17 +588,46 @@ class Triangulate_polygon_soup_modifier
*/
visitor.before_subface_creations(polygon);

const FT p1p3 = cross_product(p2-p1, p3-p2) * cross_product(p0-p3, p1-p0);
const FT p0p2 = cross_product(p1-p0, p1-p2) * cross_product(p3-p2, p3-p0);
if(p0p2 > p1p3)

typename Traits::Vector_3 p0p1=p1-p0;
typename Traits::Vector_3 p1p2=p2-p1;
typename Traits::Vector_3 p2p3=p3-p2;
typename Traits::Vector_3 p0p3=p3-p0;

const FT delta1 = cross_product(p1p2, p2p3) * cross_product(-p0p3, p0p1);
const FT delta2 = cross_product(p0p1, -p1p2) * cross_product(p2p3, p0p3);
if (delta1!=delta2)
{
triangulated_polygons.push_back({polygon[0], polygon[1], polygon[2]});
triangulated_polygons.push_back({polygon[0], polygon[2], polygon[3]});
if(delta2 > delta1)
{
triangulated_polygons.push_back({polygon[0], polygon[1], polygon[2]});
triangulated_polygons.push_back({polygon[0], polygon[2], polygon[3]});
}
else
{
triangulated_polygons.push_back({polygon[0], polygon[1], polygon[3]});
triangulated_polygons.push_back({polygon[1], polygon[2], polygon[3]});
}
}
else
{
triangulated_polygons.push_back({polygon[0], polygon[1], polygon[3]});
triangulated_polygons.push_back({polygon[1], polygon[2], polygon[3]});
PID mid =
*(std::min_element)(polygon.begin(), polygon.end(),
[&points,pm](PID id1 , PID id2)
{
return lexicographically_xyz_smaller(get(pm, points[id1]),
get(pm, points[id2]));
});
if (mid==0|| mid==2)
{
triangulated_polygons.push_back({polygon[0], polygon[1], polygon[2]});
triangulated_polygons.push_back({polygon[0], polygon[2], polygon[3]});
}
else
{
triangulated_polygons.push_back({polygon[0], polygon[1], polygon[3]});
triangulated_polygons.push_back({polygon[1], polygon[2], polygon[3]});
}
}

visitor.after_subface_created(triangulated_polygons[triangulated_polygons.size()-2]);
Expand Down
2 changes: 1 addition & 1 deletion ...mesh_processing/test/Polygon_mesh_processing/remeshing_with_isolated_constraints_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ int main(int, char**)

std::set<face_descriptor> fs;
auto selected_faces = make_boolean_property_map(fs);
fs.insert(*(faces(sm).begin()));
fs.insert(Polygon_mesh::Face_index(190));
CGAL::expand_face_selection(fs, sm, 1, selected_faces, CGAL::Emptyset_iterator());
std::cout << fs.size() << " faces in the range" << std::endl;
assert(fs.size() == 4);
Expand Down
28 changes: 14 additions & 14 deletions Polygon_mesh_processing/test/Polygon_mesh_processing/test_pmp_clip.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -394,31 +394,31 @@ void test()

// -> closed mesh, true/true
PMP::clip(tm1, K::Plane_3(-1,0,0,0), params::use_compact_clipper(true).clip_volume(true));
assert(faces(tm1).size() == 12);
assert(faces(tm1).size() == 14);
assert(CGAL::is_closed(tm1));

// -> closed mesh, false/true
PMP::clip(tm1, K::Plane_3(-1,0,0,0), params::use_compact_clipper(false).clip_volume(true));
assert(faces(tm1).size() == 12);
assert(faces(tm1).size() == 14);
assert(CGAL::is_closed(tm1));

// -> closed mesh, true/false
PMP::clip(tm1, K::Plane_3(-1,0,0,0), params::use_compact_clipper(true).clip_volume(false));
assert(faces(tm1).size() == 12);
assert(faces(tm1).size() == 14);
assert(CGAL::is_closed(tm1));

// -> closed mesh, false/false
PMP::clip(tm1, K::Plane_3(1,0,0,-1), params::use_compact_clipper(false).clip_volume(false));
assert(faces(tm1).size() == 10);
assert(faces(tm1).size() == 12);
assert(!CGAL::is_closed(tm1));

// -> open mesh true/true
PMP::clip(tm1, K::Plane_3(-1,0,0,0), params::use_compact_clipper(true).clip_volume(true));
assert(faces(tm1).size() == 10);
assert(faces(tm1).size() == 12);

// -> open mesh true/false
PMP::clip(tm1, K::Plane_3(-1,0,0,0), params::use_compact_clipper(true).clip_volume(false));
assert(faces(tm1).size() == 10);
assert(faces(tm1).size() == 12);

// -> open mesh false/false
PMP::clip(tm1, K::Plane_3(-1,0,0,0), params::use_compact_clipper(false).clip_volume(false));
Expand Down Expand Up @@ -540,7 +540,7 @@ void test()
TriangleMesh tm1;
std::ifstream("data-coref/open_large_cube.off") >> tm1;
PMP::clip(tm1, K::Plane_3(0,0,-1,1), CGAL::parameters::use_compact_clipper(true));
assert(vertices(tm1).size()==176);
assert(vertices(tm1).size()==178);
}

{
Expand All @@ -554,7 +554,7 @@ void test()
TriangleMesh tm1;
std::ifstream("data-coref/open_large_cube.off") >> tm1;
PMP::clip(tm1, K::Plane_3(0,0,-1,1), CGAL::parameters::use_compact_clipper(true).allow_self_intersections(true));
assert(vertices(tm1).size()==176);
assert(vertices(tm1).size()==178);
}
}

Expand Down Expand Up @@ -803,11 +803,11 @@ void test_isocuboid()
assert(meshes.size() == 10);
//if the order is not deterministc, put the num_vertices in a list and check
//if the list does contain all those numbers.
assert(num_vertices(meshes[0]) == 2657);
assert(num_vertices(meshes[0]) == 2663);
assert(num_vertices(meshes[1]) == 131 );
assert(num_vertices(meshes[2]) == 32 );
assert(num_vertices(meshes[3]) == 123 );
assert(num_vertices(meshes[4]) == 220 );
assert(num_vertices(meshes[3]) == 125 );
assert(num_vertices(meshes[4]) == 224 );
assert(num_vertices(meshes[5]) == 107 );
assert(num_vertices(meshes[6]) == 121 );
assert(num_vertices(meshes[7]) == 56 );
Expand Down Expand Up @@ -837,8 +837,8 @@ void test_isocuboid()
for (int i=0; i<4; ++i)
sizes.insert(vertices(meshes[i]).size());

assert(sizes.count(22)==1);
assert(sizes.count(23)==1);
assert(sizes.count(20)==1);
assert(sizes.count(21)==1);
assert(sizes.count(7)==1);
assert(sizes.count(4)==1);

Expand All @@ -853,7 +853,7 @@ void test_isocuboid()
assert(meshes.size() == 2);
//if the order is not deterministc, put the num_vertices in a list and check
//if the list does contain all those numbers.
assert(vertices(meshes[0]).size() == 22);
assert(vertices(meshes[0]).size() == 20);
assert(vertices(meshes[1]).size() == 4);
}
int main()
Expand Down

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