Function offsetOneDirection

source/MRVoxels/MROffset.cpp:338–384

}

Expected<Mesh> offsetOneDirection( const MeshPart& mp, float offset, const GeneralOffsetParameters& params /*= {} */ )
{
    MR_TIMER;
    const bool unsignedOffset = params.signDetectionMode == SignDetectionMode::Unsigned;
    auto res = generalOffsetMesh( mp, unsignedOffset ? std::abs( offset ) : offset, params );
    if ( !res )
        return res;

    auto& resMesh = res.value();

    if ( unsignedOffset )
    {
        // delete shell faces from resMesh that project on wrong side of input mesh

        // do not trust degenerate faces with huge aspect ratios
        auto badFaces = findDegenerateFaces( mp, 1000 ).value();
        // do not trust only boundary degenerate faces (excluding touching the boundary only by short edge)
        BitSetParallelFor( badFaces, [&] ( FaceId f )
        {
            float perimeter = 0;
            float bdLen = 0;
            for ( EdgeId e : leftRing( mp.mesh.topology, f ) )
            {
                auto elen = mp.mesh.edgeLength( e );
                perimeter += elen;
                if ( mp.mesh.topology.isBdEdge( e, mp.region ) )
                    bdLen += elen;
            }
            if ( perimeter * 0.1f >= bdLen )
                badFaces.reset( f );
        } );
        const auto goodFaces = mp.mesh.topology.getFaceIds( mp.region ) - badFaces;

        // for open input mesh, let us find only necessary portion on the shell
        auto innerFaces = findInnerShellFacesWithSplits( MeshPart{ mp.mesh, &goodFaces }, resMesh,
            {
                .side = offset > 0 ? Side::Positive : Side::Negative
            } );
        resMesh.topology.deleteFaces( resMesh.topology.getValidFaces() - innerFaces );
        resMesh.pack();

        if ( offset < 0 )
            resMesh.topology.flipOrientation();
    }

    return resMesh;
}

Expected<Mesh> offsetPolyline( const Polyline3& polyline, float offset, const OffsetParameters& params /*= {} */ )
{