Introduce uniteComponents function (#6365)

Author: Grantim

source/MRMesh/MRUniteManyMeshes.cpp

@@ -9,6 +9,8 @@
 #include "MRMeshCollidePrecise.h"
 #include "MRBox.h"
 #include "MRParallelFor.h"
+#include "MRMeshComponents.h"
+#include "MRBitSetParallelFor.h"
 #include <random>
 
 namespace MR
@@ -347,4 +349,56 @@ Expected<Mesh> uniteManyMeshes(
     return reducer.resultMesh;
 }
 
+Expected<Mesh> uniteComponents( const Mesh& mesh, const UniteComponentsParams& params )
+{
+    MR_TIMER;    
+    if ( !mesh.topology.isClosed() )
+    {
+        assert( !"uniteComponents: require closed mesh" );
+        return unexpected( "Mesh is not closed." );
+    }
+    auto mapAndNum = MeshComponents::getAllComponentsMap( mesh );
+    if ( !reportProgress( params.baseParams.progressCb, 0.1f ) )
+        return unexpectedOperationCanceled();
+    std::vector<Mesh> components( mapAndNum.second );
+    std::vector<const Mesh*> meshPtrs( mapAndNum.second );
+    auto keepGoing = ParallelFor( components, [&] ( size_t i )
+    {
+        FaceBitSet compBs( mesh.topology.faceSize() );
+        BitSetParallelFor( mesh.topology.getValidFaces(), [&] ( FaceId f )
+        {
+            if ( RegionId( i ) == mapAndNum.first[f] )
+                compBs.set( f );
+        } );
+        components[i].addMeshPart( MeshPart( mesh, &compBs ) );
+
+        if ( params.trySelfBoolean )
+        {
+            auto sbRes = selfBoolean( components[i] );
+            if ( sbRes.has_value() )
+            {
+                sbRes->deleteFaces( sbRes->topology.getValidFaces() - MeshComponents::getLargestComponent( *sbRes ) );
+                components[i] = std::move( *sbRes );
+            }
+        }
+        if ( params.flipInverted && components[i].volume() < 0.0f )
+            components[i].topology.flipOrientation();
+
+        meshPtrs[i] = &components[i];
+
+        compBs = {}; // reduce peek memory
+
+        if ( params.expansionRatio != 0.0f )
+        {
+            auto center = components[i].findCenterFromFaces();
+            components[i].transform( AffineXf3f::xfAround( Matrix3f::scale( 1.0f + params.expansionRatio ), center ) );
+        }
+    }, subprogress( params.baseParams.progressCb, 0.1f, 0.4f ) );
+    if ( !keepGoing )
+        return unexpectedOperationCanceled();
+    UniteManyMeshesParams ump = params.baseParams;
+    ump.progressCb = subprogress( params.baseParams.progressCb, 0.4f, 1.0f );
+    return uniteManyMeshes( meshPtrs, ump );
+}
+
 }

source/MRMesh/MRUniteManyMeshes.h

@@ -51,10 +51,32 @@ struct UniteManyMeshesParams
     ProgressCallback progressCb;
 };
 
-// Computes the surface of objects' union each of which is defined by its own surface mesh
-// - merge non intersecting meshes first
-// - unite merged groups
+/// Computes the surface of objects' union each of which is defined by its own surface mesh
+/// - merge non intersecting meshes first
+/// - unite merged groups
 MRMESH_API Expected<Mesh> uniteManyMeshes( const std::vector<const Mesh*>& meshes, 
     const UniteManyMeshesParams& params = {} );
 
+/// Parameters structure for uniteComponents function
+struct UniteComponentsParams
+{
+    /// Basic parameters of multi unite
+    UniteManyMeshesParams baseParams;
+
+    /// Per component expansion ratio, if !=0 each component is expanded on 1+expRatio around its own centroid
+    float expansionRatio = 0.0f;
+
+    /// If enabled flips orientation for componentns with negative volume
+    bool flipInverted = true;
+
+    /// Try experimental self-boolean for each component
+    /// not recommended yet
+    /// TODO: update when self-boolean is finalized
+    bool trySelfBoolean = false;
+};
+
+/// Unites components of single mesh together
+/// note: this function require closed mesh
+MRMESH_API Expected<Mesh> uniteComponents( const Mesh& mesh, const UniteComponentsParams& params = {} );
+
 }