[MacRuby-devel] Some OpenGL sample code

[Julien Jassaud]

Hello to everyone,

I tried to port two OpenGL sample code examples from the ADC in MacRuby ( and plan to port some more ). You can find both projects here : http://github.com/sojastar

Both kind of work but have problems I can't find solutions to so I turn to the list for a little help.


One of the examples ( MacRuby-BoingX ) randomly crashes, either on launch or exit, about one time out of five. When launching the application from XCode, I get :

Program received signal:  “EXC_BAD_ACCESS”.

which suggests a memory access error. It is not unlikely since the OpenGL functions use a lot of pointers. I am trying to use DTrace to identify the problem but it is very new territory for me. I wrote a script returning the name of the last function called. I get a different result for every crash. I imagine part of my data ( most often, the vertex data ) must be corrupted, and maybe from the various pointer operations I have to do to use OpenGL. Has anyone any suggestion on how I could troubleshoot such a problem ?


The problem with the second example is directly related to pointers. The function CGLQueryRendererInfo function expects a pointer to a CGLRendererInfoObj object as its second argument. After the call, the pointer points to a valid CGLRendererInfoObj object. So I did something like this :

renderer_info	= Pointer.new_with_type("^{_CGLRendererInfoObj}")
renderer_error	= CGLQueryRendererInfo(display_mask, renderer_info, renderer_count)

and get :

expected instance of Pointer of type `^{_CGLRendererInfoObject}', got `^{_CGLRendererInfoObj}' (TypeError)

If I change the pointer type to '^{_CGLRendererInfoObject}', CGLQueryRendererInfo doesn't complain anymore, but all other following functions using the CGLRendererInfoObj do. Could this be a bridge support problem ? As anyone who has a better background in Cocoa any idea ? I know some things should be done in bundles but, for sample code, I thought it would be good to try to go Ruby all the way.


My configuration : Intel Core 2 Duo MacBook Pro, Mac OS 10.6.2, MacRuby 0.5b2


Thanks,
Julien Jassaud