Local Triangulations: compute oppositely oriented; fix orientLocalTri…

…angulations (MeshInspector#2217)
emil-peters · Feb 12, 2024 · aa1c621 · aa1c621
1 parent 16399f1
commit aa1c621
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Showing 2 changed files with 36 additions and 20 deletions.
diff --git a/source/MRMesh/MRLocalTriangulations.cpp b/source/MRMesh/MRLocalTriangulations.cpp
@@ -113,7 +113,7 @@ void orientLocalTriangulations( AllLocalTriangulations & triangs, const VertCoor
             const auto next = triangs.neighbors[n + 1 < nend ? n + 1 : nbeg];
             if ( curr == bd )
             {
-                otherBd = bd;
+                otherBd = next;
                 continue;
             }
             const auto d = dot( normals[c], cross( coords[next] - cp, coords[curr] - cp ) );
@@ -130,11 +130,19 @@ void orientLocalTriangulations( AllLocalTriangulations & triangs, const VertCoor
     } );
 }
 
-static ParallelHashMap<UnorientedTriangle, int, UnorientedTriangleHasher> makeTriangleHashMap( const AllLocalTriangulations & triangs )
+struct Repetitions
+{
+    unsigned char sameOriented : 4 = 0;
+    unsigned char oppositeOriented : 4 = 0;
+};
+
+static_assert( sizeof( Repetitions ) == 1 );
+
+static ParallelHashMap<UnorientedTriangle, Repetitions, UnorientedTriangleHasher> makeTriangleHashMap( const AllLocalTriangulations & triangs )
 {
     MR_TIMER
 
-    ParallelHashMap<UnorientedTriangle, int, UnorientedTriangleHasher> map;
+    ParallelHashMap<UnorientedTriangle, Repetitions, UnorientedTriangleHasher> map;
     ParallelFor( size_t(0), map.subcnt(), [&]( size_t myPartId )
     {
         for ( VertId v = 0_v; v + 1 < triangs.fanRecords.size(); ++v )
@@ -147,47 +155,54 @@ static ParallelHashMap<UnorientedTriangle, int, UnorientedTriangleHasher> makeTr
                 if ( triangs.neighbors[n] == border )
                     continue;
                 const auto next = triangs.neighbors[n + 1 < nend ? n + 1 : nbeg];
-                const UnorientedTriangle triplet({ v, next, triangs.neighbors[n] });
+                bool flippped = false;
+                const UnorientedTriangle triplet( { v, next, triangs.neighbors[n] }, &flippped );
                 const auto hashval = map.hash( triplet );
                 const auto idx = map.subidx( hashval );
                 if ( idx != myPartId )
                     continue;
-                auto [it, inserted] = map.insert( { triplet, 0 } );
-                if ( !inserted )
-                    ++it->second;
+                Repetitions & r = map[triplet];
+                if ( flippped )
+                    ++r.oppositeOriented;
+                else
+                    ++r.sameOriented;
             }
         }
     } );
     return map;
 }
 
-VotesForTriangles computeTrianglesRepetitions( const AllLocalTriangulations & triangs )
+TrianglesRepetitions computeTrianglesRepetitions( const AllLocalTriangulations & triangs )
 {
     MR_TIMER
 
     const auto map = makeTriangleHashMap( triangs );
 
-    VotesForTriangles res{};
+    TrianglesRepetitions res{};
     for ( auto & [key, val] : map )
     {
-        assert( val >= 0 && val <= 2 );
-        ++res[val];
+        int c = val.sameOriented + val.oppositeOriented;
+        assert( c >= 1 && c <= 3 );
+        ++res[c];
+        if ( val.sameOriented >= 1 && val.oppositeOriented >= 1 )
+            ++res[0];
     }
     return res;
 }
 
 std::vector<UnorientedTriangle> findRepeatedTriangles( const AllLocalTriangulations & triangs, int repetitions )
 {
     MR_TIMER
-    assert( repetitions >= 0 && repetitions <= 2 );
+    assert( repetitions >= 1 && repetitions <= 3 );
 
     const auto map = makeTriangleHashMap( triangs );
 
     std::vector<UnorientedTriangle> res;
     for ( auto & [key, val] : map )
     {
-        assert( val >= 0 && val <= 2 );
-        if ( val == repetitions )
+        int c = val.sameOriented + val.oppositeOriented;
+        assert( c >= 1 && c <= 3 );
+        if ( c == repetitions )
             res.push_back( key );
     }
     return res;

diff --git a/source/MRMesh/MRLocalTriangulations.h b/source/MRMesh/MRLocalTriangulations.h
@@ -59,15 +59,16 @@ struct AllLocalTriangulations
 /// orient neighbors around each point so they will be in clockwise order if look from the top of target normal
 MRMESH_API void orientLocalTriangulations( AllLocalTriangulations & triangs, const VertCoords & coords, const VertNormals & normals );
 
-/// TrianglesRepetitions[0] contains the number of unoriented triangles that appear in one local triangulation only
-/// TrianglesRepetitions[1] contains the number of unoriented triangles that appear in exactly two local triangulations
-/// TrianglesRepetitions[2] contains the number of unoriented triangles that appear in three local triangulations
-using VotesForTriangles = std::array<int, 3>;
+/// TrianglesRepetitions[0] contains the number of triangles that appear in different local triangulations with opposite orientations
+/// TrianglesRepetitions[1] contains the number of unoriented triangles that appear in one local triangulation only
+/// TrianglesRepetitions[2] contains the number of unoriented triangles that appear in exactly two local triangulations
+/// TrianglesRepetitions[3] contains the number of unoriented triangles that appear in three local triangulations
+using TrianglesRepetitions = std::array<int, 4>;
 
 /// computes statistics about the number of triangle repetitions in local triangulations
-[[nodiscard]] MRMESH_API VotesForTriangles computeTrianglesRepetitions( const AllLocalTriangulations & triangs );
+[[nodiscard]] MRMESH_API TrianglesRepetitions computeTrianglesRepetitions( const AllLocalTriangulations & triangs );
 
-/// from local triangulations returns all unoriented with given number of repetitions each in [0,2]
+/// from local triangulations returns all unoriented with given number of repetitions each in [1,3]
 [[nodiscard]] MRMESH_API std::vector<UnorientedTriangle> findRepeatedTriangles( const AllLocalTriangulations & triangs, int repetitions );
 
 } //namespace MR