Join Groups Into Meshes

Mesher.cs

using System;
using Rhino;
using Rhino.DocObjects;
using Rhino.Geometry;
using System.Collections.Generic;


Dictionary<int, List<RhinoObject>> map = new Dictionary<int, List<RhinoObject>>();
MeshingParameters meshingParameters = MeshingParameters.Minimal;
meshingParameters.SimplePlanes = true;
meshingParameters.MinimumEdgeLength = 5 * RhinoMath.UnitScale(UnitSystem.Millimeters, RhinoDoc.ActiveDoc.ModelUnitSystem);
meshingParameters.GridAspectRatio = 1000;
meshingParameters.GridMinCount = 1;

foreach (RhinoObject obj in Rhino.RhinoDoc.ActiveDoc.Objects.GetObjectList(new ObjectEnumeratorSettings()
{
    DeletedObjects = false,
    HiddenObjects = false,
    LockedObjects = false,
    SelectedObjectsFilter = true
}))
{
    if (obj is MeshObject || obj.IsMeshable(Rhino.Geometry.MeshType.Preview))
    {
        int[] groups = obj.GetGroupList();
        if (groups == null || groups.Length == 0) continue;
        //int ind = groups[0];
        foreach (var ind in groups)
        {
            if (!map.TryGetValue(ind, out List<RhinoObject> list)) {
                list = new List<RhinoObject>();
                map.Add(ind, list);
            }
            list.Add(obj);
        }

    }
}

Rhino.RhinoDoc.ActiveDoc.Views.RedrawEnabled = false;

try {
    foreach (var kvp in map) {
        if (kvp.Value.Count <= 1) continue;

        var mesh = new Mesh();

        var layerIndex = kvp.Value[0].Attributes.LayerIndex;

        foreach (var obj in kvp.Value)
        {
            if (obj.IsDeleted) continue;
            if (obj is MeshObject meshObj) 
            {
                mesh.Append(meshObj.MeshGeometry);
                if (!meshObj.MeshGeometry.IsValidWithLog(out string slog))
                {
                    
                }
            }
            else {
                obj.CreateMeshes(MeshType.Preview, meshingParameters, false);
                foreach (var m in obj.GetMeshes(MeshType.Preview)) {
                    mesh.Append(m);
                }
            }
            Rhino.RhinoDoc.ActiveDoc.Objects.Delete(obj, true);
        }

        mesh.Faces.CullDegenerateFaces();
        mesh.Vertices.CullUnused();

         Rhino.RhinoDoc.ActiveDoc.Objects.Add(mesh, new ObjectAttributes() {
           LayerIndex = layerIndex,
        });
    }
}
finally {
    Rhino.RhinoDoc.ActiveDoc.Views.RedrawEnabled = true;
}



Console.WriteLine("OK");