Window Selecting

This brief guide demonstrates how to drag a window to select objects.


The CRhinoGetObject class is used for selecting Rhino objects. When active, CRhinoGetObject object will allow the user to select objects either by picking them or by dragging a crossing window. But, using C/C++, it is possible to write your own object picking class or function. The heart of such a tool is the CRhinoPickContext which defines the rules for the picking. Once the rules have been defined, you can use CRhinoDoc::PickObjects to do the work.


The following sample code demonstrates how to drag a window to select objects.

CRhinoCommand::result CCommandTest::RunCommand( const CRhinoCommandContext& context )
  CRhinoGetPoint gp;
  gp.SetCommandPrompt( L"Drag a window to select objects" );
  gp.SetGetPointCursor( RhinoApp().m_default_cursor );
  CRhinoGet::result res = gp.Get2dRectangle( 0, 0, FALSE, PS_DOT );
  if( res != CRhinoGet::rect2d )
    return failure;

  CRect pick_rect = gp.Rectangle2d();
  CRhinoView* view = gp.View();

  CRhinoPickContext pick_context;
  pick_context.m_go = 0;
  pick_context.m_view = view;
  pick_context.m_pick_style = CRhinoPickContext::window_pick;
  pick_context.m_bPickGroups = true;
  switch( view->Viewport().DisplayMode() )
    case ON::shaded_display:
    case ON::renderpreview_display:
      pick_context.m_pick_mode = CRhinoPickContext::shaded_pick;

  CRhinoObjRefArray pick_list;
  int pick_count = 0;
  if( view->Viewport().GetPickXform(pick_rect, pick_context.m_pick_region.m_xform) )
    POINT screen_point = pick_rect.BottomRight();
    view->ActiveViewport().VP().GetFrustumLine( screen_point.x, screen_point.y, pick_context.m_pick_line );
    int i, pick_count = context.m_doc.PickObjects( pick_context, pick_list );
    for( i = 0; i < pick_count; i++ )
      const CRhinoObject* obj = pick_list[i].Object();
      if( obj && obj->IsSelectable() )
        obj->Select( true );
    if( pick_count )

  return success;