Function xyPlaneMeshIntersect

source/MRMesh/MRMeshIntersect.cpp:485–554

}

void xyPlaneMeshIntersect( const MeshPart& meshPart, float zLevel,
    FaceBitSet * fs, UndirectedEdgeBitSet * ues, VertBitSet * vs, std::vector<FaceId> * fsVec )
{
    MR_TIMER;
    assert( fs || ues || vs || fsVec );

    const auto& m = meshPart.mesh;
    const auto& tree = m.getAABBTree();
    if( tree.nodes().empty() )
        return;

    assert( !fs  || fs->size()  >= m.topology.faceSize() );
    assert( !ues || ues->size() >= m.topology.undirectedEdgeSize() );
    assert( !vs  || vs->size()  >= m.topology.vertSize() );

    constexpr int maxTreeDepth = 32;
    NodeId nodesStack[maxTreeDepth];
    int currentNode = -1;

    auto addNode = [&]( NodeId nid )
    {
        const auto & box = tree[nid].box;
        if ( box.min.z <= zLevel && box.max.z >= zLevel )
            nodesStack[++currentNode] = nid;
    };
    addNode( tree.rootNodeId() );

    while( currentNode >= 0 )
    {
        if( currentNode >= maxTreeDepth ) // max depth exceeded
        {
            spdlog::critical( "Maximal AABBTree depth reached!" );
            assert( false );
            break;
        }

        const auto& node = tree[nodesStack[currentNode--]];
        if( node.leaf() )
        {
            auto face = node.leafId();
            if( !meshPart.region || meshPart.region->test( face ) )
            {
                if ( fs )
                    fs->set( face );
                if ( fsVec )
                    fsVec->push_back( face );
                if ( ues || vs )
                {
                    EdgeId e0, e1, e2;
                    m.topology.getTriEdges( face, e0, e1, e2 );
                    if ( ues )
                    {
                        ues->set( e0 );
                        ues->set( e1 );
                        ues->set( e2 );
                    }
                    if ( vs )
                    {