How to Remove Duplicate Vertices When Merging Two Meshes

[Irovel]

Hi!
I am trying to merge two meshes. Initially, I used AddPart(), but I encountered difficulties when attempting to remove duplicate points. After looking into it further, I came across discussion #3906, where it was suggested to use MeshBuilder::addTriangles. However, despite following the advice, it seems that mesh B was not added to mesh A, as the number of vertices and faces remained unchanged.
I would really appreciate any guidance or suggestions on how to resolve this issue.
Here are my code and the mesh preview, and thank you in advance for your help!

    auto loadRes1 = MeshLoad::fromAnySupportedFormat("A.stl");
    auto loadRes2 = MeshLoad::fromAnySupportedFormat("B.stl");
    Mesh SplintMesh = loadRes1.has_value() ? loadRes1.value() : Mesh();
    Mesh PartMesh = loadRes2.has_value() ? loadRes2.value() : Mesh();

    int VertNum = int(SplintMesh.topology.numValidVerts());
    int faceNum = int(SplintMesh.topology.numValidFaces());
    std::cout << "ori: " << VertNum << " " << faceNum << std::endl;

    Triangulation PartTris = PartMesh.topology.getTriangulation();
    MeshBuilder::BuildSettings buildSettings;
    buildSettings.shiftFaceId = SplintMesh.topology.numValidFaces();
    MeshBuilder::addTriangles(SplintMesh.topology, PartTris, buildSettings);

    VertNum = int(SplintMesh.topology.numValidVerts());
    faceNum = int(SplintMesh.topology.numValidFaces());
    std::cout << "new: " << VertNum << " " << faceNum << std::endl;

[Grantim]

Hello!

MeshBuilder::addTriangles should work when vertices of two meshes are already indexed correctly: meaning that "duplicated" vertices have same indices in "SplintMesh" and in "PartMesh" topologies, but it actually cannot be guaranteed within stl format.

Something like this should work if boundary vertices of two meshes are the same

    auto loadRes1 = MeshLoad::fromAnySupportedFormat("A.stl");
    auto loadRes2 = MeshLoad::fromAnySupportedFormat("B.stl");
    Mesh SplintMesh = loadRes1.has_value() ? loadRes1.value() : Mesh();
    Mesh PartMesh = loadRes2.has_value() ? loadRes2.value() : Mesh();
    SplintMesh.addMesh( PartMesh );
    MeshBuilder::uniteCloseVertices( SplintMesh, 0.0f, true ); // this function should merge boundary vertices with same coordinates

[Irovel]

Thank you for your help, the issue has been perfectly resolved!