[Mono-devel-list] Tao Glut library and NullReference in wrapper_mono_string

Kamil Skalski nazgul at omega.pl
Fri May 21 10:21:14 EDT 2004


I've been playing with Tao (http://www.randyridge.com/Tao/Default.aspx) 
bindings to OpenGl and Glut libraries. I was succesful in running some 
tescases from Redbook examples from Tao sources, but some of them crached at 
very beginning:

Unhandled Exception: System.NullReferenceException: A null value was found 
where an object instance was required.
in (unmanaged) (wrapper managed-to-native) 
System.Object:__icall_wrapper_mono_string_to_utf8 (object)
in <0x00004> (wrapper managed-to-native) 
System.Object:__icall_wrapper_mono_string_to_utf8 (object)
in <0x0010b> (wrapper managed-to-native) Tao.Glut.Glut:glutInit 
in <0x000d4> Tao.Glut.Glut:glutInit ()
in <0x0000e> Redbook.Aaindex:Main ()

This is the first function called in program, but unfortunetly not all 
examples crach on it...

I took a look at Tao sources and glutInit function has the following code:

      public static void glutInit() { 
            string[] argsArray = Environment.GetCommandLineArgs(); 
            StringBuilder[] args = new StringBuilder[argsArray.Length]; 
            int argsLength = args.Length; 
            for(int i = 0; i < argsArray.Length; i++) { 
                args[i] = new StringBuilder(argsArray[i],       
            glutInit(ref argsLength, args); 

where glutInit (ref argsLength, args); 
is a call to native libGl.so library:

      [DllImport(GLUT_NATIVE_LIBRARY), SuppressUnmanagedCodeSecurity] 
        public static extern void glutInit(ref int argcp, StringBuilder[] 

Has anyone tried running Tao on mono? I compiled its libraries from command 
line suppying -define:LINUX to compiler. The above exception seems to be 
mono-related bug, not Tao.
I also tried to compile Tao libraries with NAnt (the entire project uses it 
for building). I was almost succesful, but I failed on project's dependency 
on ildasm - it uses it to generate some keys for libraries. Is there any mono 
counterpart for building those keys or way to switch their building in NAnt?

Kamil Skalski

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