Method buildGridMesh

source/MRMesh/MRMeshTopology.cpp:1618–1752

}

bool MeshTopology::buildGridMesh( const GridSettings & settings, ProgressCallback cb )
{
    MR_TIMER;

    stopUpdatingValids();

    // we use resizeNoInit because expect vertices/faces/edges to be tightly packed (no deleted elements within valid range)
    // note: some vertices might be valid but have no edge
    edgePerVertex_.resizeNoInit( settings.vertIds.tsize );
    edgePerFace_.resizeNoInit( settings.faceIds.tsize );
    edges_.resizeNoInit( 2 * settings.uedgeIds.tsize );

    auto getVertId = [&]( Vector2i v ) -> VertId
    {
        if ( v.x < 0 || v.x > settings.dim.x || v.y < 0 || v.y > settings.dim.y )
            return VertId();
        return settings.vertIds.b[ v.x + v.y * ( settings.dim.x + 1 ) ];
    };
    auto getFaceId = [&]( Vector2i v, GridSettings::TriType triType ) -> FaceId
    {
        if ( v.x < 0 || v.x >= settings.dim.x || v.y < 0 || v.y >= settings.dim.y )
            return FaceId();
        return settings.faceIds.b[ 2 * ( v.x + v.y * settings.dim.x ) + (int)triType ];
    };
    auto getEdgeId = [&]( Vector2i v, GridSettings::EdgeType edgeType ) -> EdgeId
    {
        if ( v.x < 0 || v.x > settings.dim.x || v.y < 0 || v.y > settings.dim.y )
            return EdgeId();
        auto ue = settings.uedgeIds.b[ 4 * ( v.x + v.y * ( settings.dim.x + 1 ) ) + (int)edgeType ];
        return ue ? EdgeId( ue ) : EdgeId();
    };

    struct EdgeFace
    {
        EdgeId e;
        FaceId f; //to the left of e
    };
    tbb::enumerable_thread_specific<std::vector<EdgeFace>> edgeRingPerThread;
    auto result = ParallelFor( 0, settings.dim.y + 1, edgeRingPerThread, [&]( int y, std::vector<EdgeFace> & edgeRing )
    {
        Vector2i pos;
        pos.y = y;
        for ( pos.x = 0; pos.x <= settings.dim.x; ++pos.x )
        {
            if ( auto da = getEdgeId( pos, GridSettings::EdgeType::DiagonalA ) )
            {
                if ( const auto fl = getFaceId( pos, GridSettings::TriType::Lower ) )
                    edgePerFace_[fl] = da.sym();
                if ( const auto fu = getFaceId( pos, GridSettings::TriType::Upper ) )
                    edgePerFace_[fu] = da;
            }
            else if ( auto db = getEdgeId( pos, GridSettings::EdgeType::DiagonalB ) )
            {
                if ( const auto fl = getFaceId( pos, GridSettings::TriType::Lower ) )
                    edgePerFace_[fl] = db;
                if ( const auto fu = getFaceId( pos, GridSettings::TriType::Upper ) )
                    edgePerFace_[fu] = db.sym();
            }