Modifying Advanced Display Settings
Windows only

by Dale Fugier (Last updated:  Wednesday, December 5, 2018)

Overview

The advanced display features in Rhino give the user almost unlimited control over how objects appear on the screen. All of these features are also exposed to the C/C++ developer.

Rhino maintains advanced display settings using the CDisplayPipelineAttributes class. Rhino will maintain a number of these objects, one for each advanced display setting created by the user (i.e. Wireframe, Shaded, Rendered, Ghosted, X-Ray, etc.) or by 3rd party plugins.

The C/C++ developer can gain access to these objects using the Display Attributes Manager, which is implemented as a number of static functions found on the CRhinoDisplayAttrsMgr class.

The process for updating advanced display settings is similar to updating or modifying other objects in Rhino.

  1. Make a copy of the original.
  2. Modify one or more setting or parameters.
  3. Replace the original object with the modified copy.

Sample

// The following example code demonstrates how to modify advanced display settings using
// the Rhino SDK. In this example, a display mode's mesh wireframe thickness (in pixels)
// will be modified.
CRhinoCommand::result CCommandTest::RunCommand( const CRhinoCommandContext& context )
{
  // Use the display attributes manager to build a list of display modes.
  // Note, these are copies of the originals...
  DisplayAttrsMgrList attrs_list;
  int attrs_count = CRhinoDisplayAttrsMgr::GetDisplayAttrsList( attrs_list );
  if( attrs_count == 0 )
    return failure;

  // Construct an options picker so the user can pick which
  // display mode they want modified
  CRhinoGetOption go;
  go.SetCommandPrompt( L"Display mode to modify mesh thickness" );

  ON_SimpleArray<int> opt_list( attrs_count );
  opt_list.SetCount( attrs_count );

  for( int i = 0; i < attrs_count; i++ )
  {
    // Verify the display mode had a valid
    // CDisplayPipelineAttributes pointer
    if( 0 == attrs_list[i].m_pAttrs )
    {
      opt_list[i] = 0;
      continue;
    }

    // Get the display attributes English name
    ON_wString english_name = attrs_list[i].m_pAttrs->EnglishName();
    english_name.Remove( L'_' );
    english_name.Remove( L' ' );
    english_name.Remove( L'-' );
    english_name.Remove( L',' );
    english_name.Remove( L'.' );

    // Get the display attributes localized name
    ON_wString local_name = attrs_list[i].m_pAttrs->LocalName();
    local_name.Remove( L'_' );
    local_name.Remove( L' ' );
    local_name.Remove( L'-' );
    local_name.Remove( L',' );
    local_name.Remove( L'.' );

    // Add the command option
    opt_list[i] = go.AddCommandOption( CRhinoCommandOptionName(english_name, local_name) );
  }

  // Get the command option
  go.GetOption();
  if( go.CommandResult() != success )
    return go.CommandResult();

  const CRhinoCommandOption* opt = go.Option();
  if( 0 == opt )
    return failure;

  // Figure out which command option was picked
  int attrs_index = -1;
  for( int i = 0; i < opt_list.Count(); i++ )
  {
    if( opt_list[i] == opt->m_option_index )
    {
      attrs_index = i;
      break;
    }
  }

  // Validate...
  if( attrs_index < 0 | attrs_index >= attrs_count )
    return failure;

  // Get the display mode requested by the user
  DisplayAttrsMgrListDesc desc = attrs_list[attrs_index];
  if( 0 == desc.m_pAttrs )
    return failure;

  // Modify the desired display mode. In this case, we
  // will just set the mesh wireframe thickness to zero.
  desc.m_pAttrs->m_nMeshWireThickness = 0;

  // Use the display attributes manager to update the display mode.
  CRhinoDisplayAttrsMgr::UpdateAttributes( desc );

  // Force the document to regenerate.
  context.m_doc.Regen();

  return success;
}