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Message-ID: <42DE917E.45C144FC@dessent.net>
Date: Wed, 20 Jul 2005 11:01:34 -0700
From: Brian Dessent <brian AT dessent DOT net>
MIME-Version: 1.0
To: cygwin AT cygwin DOT com
Subject: Re: g++ problem when attempting to cast a function pointer in an OpenGL   GLU callback
References: <1075213EFAF9BA4181A250B072635947F14C8A AT AMR-EX6 DOT ds DOT amrdec DOT army DOT mil>
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Reply-To: cygwin AT cygwin DOT com

"Day, Michael A AMRDEC/UAH" wrote:

> test.cpp:72: error: invalid conversion from `void (*)()' to `void (*)()'

Win32 API functions generally use the stdcall calling convention, not
the standard C one.  Your tcbBegin is not defined this way and this
could be what the compiler is trying to tell you, although the error
certainly isn't very clear.

If you look at glu.h:

GLAPI void APIENTRY gluTessCallback (GLUtesselator* tess, GLenum which,
_GLUfuncptr CallBackFunc);

where _GLUfuncptr is defined as:

typedef void (APIENTRY *_GLUfuncptr)();

where APIENTRY expands to "__attribute__ ((__stdcall__))".  So you'll
need to declare your callback with that attribute or else it will not
work.

Brian

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