GOoOGle's picture



I'm trying to use glade and opentk, and since 2 nights i try just to make and run the examples of gtkglarea-sharp. I finally successfully did it by adding the the Tao.OpenGl into the GAC via the line :

$gacutil /i Tao.OpenGl.dll /f /package Tao.OpenGl /root /home/gooogle/install/mono-1.2.6/lib/

My stuff lead me to get 2 questions :

First question :
why can't I add OpenTK.dll into the gac ? the result of the gacutil command was :

$gacutil /i OpenTK.dll /f /package opentk-sharp /root /home/gooogle/install/mono-1.2.6/lib/
Failure adding assembly to the cache: Attempt to install an assembly without a strong name.
$gacutil /i OpenTK.dll /f /package OpenTK /root /home/gooogle/install/mono-1.2.6/lib/
Failure adding assembly to the cache: Attempt to install an assembly without a strong name.

Second question :
I try to use OpenTK instead of Tao for the examples of gtkglarea-sharp. So i did it successfully and i could compile the examples with OpenTK instead of Tao, by replacing all the gl.glFunction with GL.Function OpenTK calls.
But i did not work when i execute, with this error :

Exception in Gtk# callback delegate
  Note: Applications can use GLib.ExceptionManager.UnhandledException to handle the exception.
System.NullReferenceException: Object reference not set to an instance of an object
  at OpenTK.OpenGL.GL.Viewport (Int32 x, Int32 y, Int32 width, Int32 height) [0x00000] 
  at GtkGL.GLWidget.OnConfigure (System.Object o, System.EventArgs e) [0x0000c] in /home/gooogle/src/gtkglarea-sharp-opentk/examples/util/GLWidget.cs:184 
  at Gtk.Widget.ConfigureEventSignalCallback (IntPtr arg0, IntPtr arg1, IntPtr gch) [0x00000] 
   at GLib.ExceptionManager.RaiseUnhandledException(System.Exception e, Boolean is_terminal)
   at Gtk.Widget.ConfigureEventSignalCallback(IntPtr arg0, IntPtr arg1, IntPtr gch)
   at Gtk.Widget.ConfigureEventSignalCallback(IntPtr , IntPtr , IntPtr )
   at Gtk.Widget.gtk_widget_show(IntPtr )
   at Gtk.Widget.gtk_widget_show(IntPtr )
   at Gtk.Widget.Show()

Moreover, when i try to add the action GL.Viewport(0, 0, 20, 20); in a test program, i got exactly the same error above.
So question is : did the init of OpenTK is it different from tao ? and if yes, what could i have to add to have the right comportment ?
Because when i grep the gtkglarea code source, i only found Tao dependancies in the Examples folders, so i suppose the created dll for gtkglarea-sharp is good.
I precise when i added a test code with an GameWindow in the same test program, it's work perfectly, so i don't have problem with dependancies of OpenTK. I think i have my openGl context not initialize. But if it's true, how tao work, without it ?

Thanks for reading me,


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JTalton's picture

You need to call OpenTK.GL.LoadAll() or something like that to initialize OpenTK.GL.

GOoOGle's picture

Hello !
Thanks a lots ! It's perfectly works !
I just add the GL.LoadAll(); before the first call to the OpenTK methods and i also add a OpenTK.OpenGL.GLU.LoadAll() to have access to the famous teapot, and moreover the gluPerspective methods and i successfully port the gtkglarea-sharp from tao to openTK !
Now it just miss a usable stetic graphical component widget for monodevelop to have exactly the same comportement than with the windows.form component.
Thank again!

the Fiddler.'s picture

I haven't had time to add the GTK# OpenGL widget to OpenTK yet, but this will come at some point in the future. It's good to know that the Tao widget works with OpenTK though.