GLUI places controls within a Panel. Before we create a panel, we must first establish a GLUI window that holds the panel. We accomplish this by creating a GLUI subwindow with the call to the function

          create_glui_subwindow

We pass to the function the handle of a GLUT window and, in particular, our Selection subwindow. (Note that the GLUI library is built on top of GLUT.) The constant GLUI_SUBWINDOW_TOP that we also passed specifies that we want our GLUI window positioned at the top of our Selection window. Create_glui_subwindow returns a pointer to a new GLUI subwindow.

Next, we create a panel with a call to GLUI_PANEL. The constructor returns a pointer to the panel class object, which we save in mainPanel. The constructor requires three parameters. The first parameter is the pointer to the GLUI object in which the panel will reside. The second parameter is a string that is shown as text on the panel. Since we do not want a label displayed with our main panel, we pass the null string as our second parameter. The third parameter is for styling the panel. The following are the three choices, of which we used the third.

  GLUI_PANEL_EMBOSSED - drawn as a sunken box
  GLUI_PANEL_RAISED   - drawn as a raised box 
  GLUI_PANEL_NONE     - drawn without a box