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    <p>As the error message says, you must use <code>&amp;StartHand::MouseButton</code> syntax to get a pointer to a member function (ptmf); this is simply mandated as part of the language.</p> <p>When using a ptmf, the function you are calling, glutMouseFunc in this case, must also expect to get a ptmf as a callback, otherwise using your non-static MouseButton won't work. Instead, a common technique is for callbacks to work with a user-supplied <code>void*</code> context, which can be the instance pointer&mdash;but the library doing the callbacks must explicitly allow this parameter. It's also important to make sure you match the ABI expected by the external library (the <em>handle_mouse</em> function below).</p> <p>Since glut <em>doesn't</em> allow user-supplied context, you have to use another mechanism: associate your objects with glut's current window. It does provide a way to get the "current window", however, and I've used this to associate a <code>void*</code> with the window. Then you simply need to create a <a href="http://en.wikipedia.org/wiki/Trampoline_%28computers%29" rel="nofollow noreferrer">trampoline</a> to do the type conversion and call the method.</p> <p>Machinery:</p> <pre><code>#include &lt;map&gt; int glutGetWindow() { return 0; } // make this example compile and run ##E## typedef std::pair&lt;void*, void (*)(void*,int,int,int,int)&gt; MouseCallback; typedef std::map&lt;int, MouseCallback&gt; MouseCallbacks; MouseCallbacks mouse_callbacks; extern "C" void handle_mouse(int button, int state, int x, int y) { MouseCallbacks::iterator i = mouse_callbacks.find(glutGetWindow()); if (i != mouse_callbacks.end()) { // should always be true, but possibly not // if deregistering and events arrive i-&gt;second.second(i-&gt;second.first, button, state, x, y); } } void set_mousefunc( MouseCallback::first_type obj, MouseCallback::second_type f ) { assert(obj); // preconditions assert(f); mouse_callbacks[glutGetWindow()] = MouseCallback(obj, f); //glutMouseFunc(handle_mouse); // uncomment in non-example ##E## handle_mouse(0, 0, 0, 0); // pretend it's triggered immediately ##E## } void unset_mousefunc() { MouseCallbacks::iterator i = mouse_callbacks.find(glutGetWindow()); if (i != mouse_callbacks.end()) { mouse_callbacks.erase(i); //glutMouseFunc(0); // uncomment in non-example ##E## } } </code></pre> <p>Example:</p> <pre><code>#include &lt;iostream&gt; struct Example { void MouseButton(int button, int state, int x, int y) { std::cout &lt;&lt; "callback\n"; } static void MouseButtonCallback( void* self, int button, int state, int x, int y ) { static_cast&lt;Example*&gt;(self)-&gt;MouseButton(button, state, x, y); } }; int main() { Example obj; set_mousefunc(&amp;obj, &amp;Example::MouseButtonCallback); return 0; } </code></pre> <p>Notice that you don't call <em>glutMouseFunc</em> directly anymore; it is managed as part of <em>[un]set_mousefunc</em>.</p> <hr> <p>Just in case it isn't clear: I've rewritten this answer so it should work for you and so that it avoids the C/C++ linkage issue being debated. It will compile and run as-is (without glut), and it should work with glut with only minor modification: comment or uncomment the 4 lines marked <code>##E##</code>.</p>
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    1. POCallback to non-static method
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    1. COYou should not use static functions as callbacks. Technically the library is expecting a C-Function. Static member methods are not C-Functions and you are just getting lucky that your compiler uses the same ABI for both. There is no requirement for it to do so. And just to grind it in, the more expensive compilers that use highly optimized ABI's (and pass parameters in registers rather than on the stack) will break with the following code.
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      1. USMartin York
    2. COActually this example is standard C++ and guaranteed to work in C++. The problem is language and compiler interop, and your point is valid in those circumstances. OpenGL is in exactly that situation. Fully answering how to specify compiler-/platform-specific ABIs when declaring the function is outside the scope of this question, however.
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    3. COI posted a question (link to follow) so that you can discuss the ABI matter more thoroughly. I'm really interested in this, because I had often used static methods to do Roger's "trampoline" trick (hehe I like that term, Roger). http://stackoverflow.com/questions/2068022/in-c-is-it-safe-portable-to-use-static-member-function-pointer-for-c-api-ballb
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      1. USEmile Cormier
 

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