Callbacks and member function pointers

[djcredo]

Hello,

I'm using C++ with OpenGL and GLUT. But I'm having problems with
callbacks.

There is a function called "glutDisplayFunc" which receives function
pointers as input, specifically "void (*func)(void)".

I'm calling the function inside the constructor of a class called
GLTestOne, and the input I am giving is to the function "void
GLTestOne::DrawGLScene()".

When I call the function, I use:

glutDisplayFunc(DrawGLScene)

.... however, the compiler complains that the pointer is of type "void
(GLTestOne::)(void)" instead of the required "void (*)(void".

How can I do this correctly? I'm still quite hazy with member function
pointers.

Cheers

[Jakob Bieling]

dj*****@gmail.com wrote:

Hello,

I'm using C++ with OpenGL and GLUT. But I'm having problems with
callbacks.

There is a function called "glutDisplayFunc" which receives function
pointers as input, specifically "void (*func)(void)".

I'm calling the function inside the constructor of a class called
GLTestOne, and the input I am giving is to the function "void
GLTestOne::DrawGLScene()".

When I call the function, I use:

glutDisplayFunc(DrawGLScene)

... however, the compiler complains that the pointer is of type "void
(GLTestOne::)(void)" instead of the required "void (*)(void".

How can I do this correctly? I'm still quite hazy with member function
pointers.

You *have to* pass a function, that does not need a this pointer.
There is no way around it. To be still able to use it, you commonly pass
a *static* member function which can then either do work or pass the
call on to the appropriate object.

hth
--
jb

(reply address in rot13, unscramble first)

[djcredo]

Thank you, I understand now. Cheers!