Sample code using GLSceneViewer1.Buffer.CreateSnapShot

procedure TForm1.TakeSnapShot;var   bm : TBitmap;

   bmp32 : TGLBitmap32;

begin   bmp32:=GLSceneViewer1.Buffer.CreateSnapShot;

   try

     bm:=bmp32.Create32BitsBitmap;

     try

       SavePictureDialog1.DefaultExt := GraphicExtension(TBitmap);

       SavePictureDialog1.Filter := GraphicFilter(TBitmap);

       if SavePictureDialog1.Execute then

         bm.SaveToFile(SavePictureDialog1.FileName);

       finally

         bm.Free;

       end;

   finally

     bmp32.Free;

   end;

end;

Theres also a demo in CVS at:

CVS/Demos/rendering/tobitmap