with Gtk.Main;
with Gtk.Window;       use Gtk.Window;
with Glu_H;            use Glu_H;
with GL_H;             use GL_H;
with Gtk.Glarea;       use Gtk.Glarea;
with Gdk.GL;           use Gdk.Gl;
with Ada.Text_IO;      use Ada.Text_IO;
with Gdk.Event;        use Gdk.Event;
with Gtk.Handlers;     use Gtk.Handlers;



package body OpenGL is

function InitGL(Area : access Gtk_GLArea_Record'Class) return Boolean is
begin
   if Make_Current(Area) then
      Glclearcolor(0.0,0.0,0.0,0.0);
      Glenable(GL_DEPTH_TEST);
      Glshademodel(GL_SMOOTH);
      end if;
   return True;
end InitGL;

function Reshape(Area : access Gtk_GLArea_Record'Class; Event : Gdk_Event) return Boolean is
begin
   if Get_Count(Event) > 0 then
      return True;
   end if;

   if Make_Current(Area) then
      Glviewport(0,0,500,500);
      Glmatrixmode(GL_PROJECTION);
      Glloadidentity;
      Gluperspective(Long_Float (45.0), Long_Float(1.3), 1.0,100.0);
      Glmatrixmode(GL_MODELVIEW);
      Glloadidentity;
   end if;
   return True;
end Reshape;

function Display(Area: access Gtk_GLArea_Record'Class; Event : Gdk_Event) return Boolean is
begin
   if Make_Current(Area) then
      Glclear(GL_COLOR_BUFFER_BIT);
      Glclear(GL_DEPTH_BUFFER_BIT);
      Glloadidentity;
      Gltranslatef(0.0,0.0,-5.0);
      Glbegin(GL_QUADS);
      Glvertex3f(-2.0,0.0,0.0);
      Glvertex3f(-2.0,2.0,0.0);
      Glvertex3f(2.0,2.0,0.0);
      Glvertex3f(2.0,0.0,0.0);
      Glend;
      Swap_Buffers(Area);
   end if;
     return True;
end Display;

end OpenGL;