ClassGL 3.6 Library Reference

COpenGL::SetSelectProcedure

void SetSelectProcedure( void (*SelectProcedure)( void* ), void* hData );

Parameters

SelectProcedure	Specifies callback procedure which COpenGL object is using for object selection. This is usually the same procedure used for scene rendering or wrapper around such procedure.
hData	Specifies the content of selection procedure callback. ClassGL will call the selection callback procedure with hData pointer as it’s parameter. The hData parameter usually specifies pointer to the class wrapping the COpenGL object.

Remarks

Provided callback procedure is usually the same method which application uses for scene rendering. The COpenGL object first switch OpenGL render mode to GL_SELECT and then calls the callback SelectProcedure with provided hData. Within the selection procedure the application should call glLoadName for each object available for selection and then draw these objects. Therefore the selection mechanism is exactly the same which OpenGL provides.

This method is available from ClassGL version 3.0

Example

int COpenGLView::OnCreate(LPCREATESTRUCT lpCreateStruct) 
{
  …
  // initialize OpenGL context
  m_OpenGL.OnCreate( ( LPARAM )m_hWnd );
  …
  // set selection methods callbacks
  m_OpenGL.SetSelectProcedure( CLASSGL_SELECTPROC SelectProc, this );
  m_OpenGL.SetSelectObjectCallback( CLASSGL_SELECTOBJECTPROC SelectObjectProc, this );
  m_OpenGL.SetOnChangeCallback( CLASSGL_ONCHANGEPROC OnChangeProc, this );
  …
  
  // indicate success
  return 0;
}

/* static */ void COpenGLView::SelectProc( COpenGLView* Me )
{
  Me->DrawScene( true );
}

/* static */ void COpenGLView::SelectObjectProc( COpenGLView* Me, int ObjectId )
{
  Me->SelectObject( ObjectId );
}

/* static */ void COpenGLView::OnChangeProc( COpenGLView* Me, SObjectInfo* Object )
{
  Me->OnChange( Object );
}

void COpenGLView::DrawScene( bool SelectObject )
{
  COglSampleDoc* pDoc = GetDocument();
  ASSERT_VALID(pDoc);
  
  // go through array of objects and draw them one by one
  for ( int i = 0; i < pDoc->m_Objects.GetSize(); i++ )
  {
    // get the object
    CMyObject*	Object =   

  
     
      
  
      
      
      (
  CMyObject* )pDoc->m_Objects.GetAt( i ); //
  save
  
  current "world view"
  matrix glPushMatrix();
//

apply object info to display object on proper
position/rotation
  m_OpenGL.ApplyObjectInfo(& Object->m_ObjectInfo );
//

if this is a "select object" call, load the object
identifier
  if( SelectObject )
glLoadName(

Object->m_ObjectInfo.ObjectId ); // draw the object Object->Draw(); // restore the
"world
  view"matrix glPopMatrix(); }
}

void COglSampleView::SelectObject( int ObjectId )
{
  COglSampleDoc* pDoc = 
  
  
             
  GetDocument(); ASSERT_VALID(pDoc); // go  through the  listof objects and
  compare
    one object id after
    another	for  ( int i=  
         
    
        0; i < pDoc->m_MyObjects.GetSize(); i++ )
    { CMyObject* MyObject= 
               
       
      ( CMyObject*) pDoc->m_MyObjects.GetAt(
    i ); if (
    ObjectId=
         
    
  


    

    = 
  
  
               
    MyObject->m_ObjectInfo.ObjectId )  { //  setreference to object
  position
    info	m_OpenGL. <    STRONG>  
      SetManipulatedObject < /STRONG> 
    
            
       ( &My->m_ObjectInfo );
      return;
    }
  }
  // call base class to unselect previously selected object
  m_OpenGL.SetManipulatedObject( NULL );
  m_OpenGL.UnsetFitSelectedInfo();
}

void CoglSampleView::OnChange( SObjectInfo* Object )
{
  COglSampleDoc* pDoc = 
  GetDocument();
  
  ASSERT_VALID(pDoc);PDoc->SetModifiedFlag( TRUE );
}