Gl Extension on Convolution

I met one problem when I tried the sample code for OpenGL 1.2 extension.
The code goes like this:
And it seems that the address for this function starts at 0X00000000… So the program terminated there. I have included the glExtension headerfile “extgl.h”.

Anyone has experience in glConvolution?

Hex Addr == 0x00000000 is ‘\0’ or NULL, which means that wglGetProcAddress(“glConvolutionParameteri”) or glXGetProcAddress(“glConvolutionParameteri”), whichever you are using, returned that value, which means it’s not implemented by your renderer or not available when you are attempting to retrieve the function.


Thank you for your reply.
I installed latest version of the graphics hardware driver and the extgl.h library. After using the sample code provided, I found that both OpenGL1.2, OpenGL1.3 and more specificly “ARB_imaging” is supported.
The problem is if those glConvolution functions are not available, why there’s no linking error in Microsoft Visual enviroment?
Is there anything I can do to use them?
Thanks again.

you know that you have to load them manually? with wglGetProcAddress? the linker can’t link them as they are not standart in the library version you have (1.1), but part of a newer version… (1.3) => an extension for 1.1

If we look into the extgl.h file, we can see that it doesn almost all the initialization for the variables/procs., fo example, wglGetProcAddress…
It is available at :
Thanks anyway.