Part of the feature edge

[xiaodongdong101]

I found that there is a global search for feature edges in the software.But if I want to find a local segment of a line.What should I do better?
For example, the cyan edge has two tangent lines at both ends.

How should I find out the local characteristic edge out

[Grantim]

Hello, we have manual edge selector tool. Finding this edge automaticaly may be challenging and require some geometry specific code, I don't think it can be done in common case.
I suggest you can do something like this:

UndirectedEdgeBitSet creaseEdges = mesh.findCreaseEdges( 15.0f/180.0f * PI_F ); // 15 deg like on your screen
UndirectedEdgeBitSet resEdges = creaseEdges;
for ( auto ue : creaseEdges )
{
    if ( !doesMeetCriteria( mesh, creaseEdges, ue ) )
        resEdges.set( ue, false );
}

In your case it can be

bool doesMeetCriteria( const Mesh& m, const UndirectedEdgeBitSet& creases , UndirectedEdgeId ue )
{
    auto lengthSq = mesh.lengthSq( ue );
    for ( auto e : orgRing( mesh.topology, EdgeId( ue ) ) ) // check length of nearby creases (around one of the edge vertices)
    {
        if ( !creases.test( e.undirected() ) )
            continue;
        if ( mesh.lengthSq( e.undirected() ) >= lengthSq )
            return false;
    }
    for ( auto e : orgRing( mesh.topology, EdgeId( ue ).sym() ) ) // check length of nearby creases (around another one of the edge vertices)
    {
        if ( !creases.test( e.undirected() ) )
            continue;
        if ( mesh.lengthSq( e.undirected() ) >= lengthSq )
            return false;
    }
    return true;
}

This code sample select first all creases edges like on your screen, than it removes all creases with neighbour creases that are longer then them. ( it have not tested this code, it may require fixes, but the idea is to make good criteria based on your specific data )

[xiaodongdong101]

Thanks a lot.That's a good way to mention it, I'll try it again