Developer: C++
Summary: Demonstrates how to create sublayers using the Rhino SDK.

I understand how to create new layers in Rhino, using the Rhino SDK. But, it is unclear to me how to create sublayers. Can you explain?

Layers can be organized into a hierarchical structure, like file folders. If a layer has a parent layer, then the ON_Layer::m_parent_layer_id member will be set to the id, or ON_Layer::m_layer_id, of the parent layer. If the layer does not have a parent layer, then the ON_Layer::m_parent_layer_id member will be set to ON_nil_uuud;

For example:

CRhinoCommand::result CCommandTest::RunCommand( const CRhinoCommandContext& context )
{
  CRhinoCommand::result rc = CRhinoCommand::failure;
  CRhinoLayerTable& layer_table = context.m_doc.m_layer_table;
 
  ON_Layer layer;
  layer.m_name = L"MyTestLayer";
 
  int layer_index = layer_table.AddLayer( layer );
  if( layer_index >= 0 | layer_index < layer_table.LayerCount() )
  {
    const CRhinoLayer& rhino_layer = layer_table[layer_index];
 
    ON_Layer sublayer;
    sublayer.m_name = L"MyTestSubLayer";
    sublayer.m_parent_layer_id = rhino_layer.m_layer_id;
 
    layer_index = layer_table.AddLayer( sublayer );
    if( layer_index >= 0 | layer_index < layer_table.LayerCount() )
      rc = CRhinoCommand::success;
  }
 
  return rc;
}