Developer: .NET
Summary: Demonstrates how to create a mesh from a surface or a polysurface.
NOTICE: The Rhino.NET SDK is deprecated in Rhino 5. This example adapted for the new RhinoCommon SDK is here.

How can I pick a surface or polysurface and then generate a mesh from it?

See the following example.

public override IRhinoCommand.result RunCommand(IRhinoCommandContext context)
{
  // Pick a surface or polysurface to mesh
  MRhinoGetObject go = new MRhinoGetObject();
  go.SetCommandPrompt("Select surface or polysurface to mesh");
  go.SetGeometryFilter(IRhinoGetObject.GEOMETRY_TYPE_FILTER.surface_object | IRhinoGetObject.GEOMETRY_TYPE_FILTER.polysrf_object);
  go.GetObjects(1, 1);
  if (go.CommandResult() != IRhinoCommand.result.success)
    return go.CommandResult();
 
  // Validate the geometry
  IOnBrep brep = go.Object(0).Brep();
  if (null == brep)
    return IRhinoCommand.result.failure;
 
  // Get your favorite meshing parameters. If you want to modify one of these, then
  // just create a copy of one of these that you can modify.
  IOnMeshParameters fast_mp = RhUtil.RhinoApp().AppSettings().RenderMeshSettings().FastMeshParameters();
  IOnMeshParameters quality_mp = RhUtil.RhinoApp().AppSettings().RenderMeshSettings().QualityMeshParameters();
  IOnMeshParameters current_mp = context.m_doc.Properties().RenderMeshSettings();
 
  // Create the meshes (1 for every brep face)
  OnMesh[] mesh_list = new OnMesh[0];
  int mesh_count = brep.CreateMesh(current_mp, ref mesh_list);
  if (0 == mesh_count || 0 == mesh_list.Length)
  {
    RhUtil.RhinoApp().Print("Unable to mesh object.\n");
    return IRhinoCommand.result.nothing;
  }
 
  // Create one big mesh from all of the mesh faces
  OnMesh mesh = new OnMesh(mesh_list[0]);
  for (int i = 1; i < mesh_count; i++)
    mesh.Append(mesh_list[i]);
 
  // TODO: do something with the mesh.
  // In is example, we'll just add it to the document.
 
  context.m_doc.AddMeshObject(mesh);
  context.m_doc.Redraw();
 
  return IRhinoCommand.result.success;
}