On 26/01/11 07:00, Henk Boom wrote: [...] > They don't exist in the .dll, or they don't exist in the header file? Having worked with OpenGL extensions (mostly on egl), the answer to this question is: both, possibly neither. The prototypes for the extension functions are set in stone by Khronos[*]. It's perfectly acceptable for the application to declare its own prototypes (or even have its own copies of the header files, copied from Khronos itself). It gets the function using *GetProcAddress(), casts it to the appropriate type, and then it can call it. As a result, it's completely undefined where the function itself resides. One possible implementation is to have *GetProcAddress() dlopen() a shared library with the given name so that the extensions get loaded on demand... [*] ...eg: GL_APICALL void GL_APIENTRY glExtGetShadersQCOM (GLuint *shaders, GLint maxShaders, GLint *numShaders); The GL_APICALL and GP_APIENTRY macros can be defined by the platform to provide platform-specific tweaks to the ABI. Normally GL_APICALL is defined to 'extern' or '__declspec(dllimport)' and GL_APIENTRY to a compiler-specific calling convention specifier like '__stdcall' or '__ccall'. Which of course means that the ABI can vary drastically depending on how your OpenGL library has been built, even on a single platform, which means that maintaining an FFI-compatible repository of function prototypes isn't adequate. Fun, eh? -- ┌─── ｄｇ＠ｃｏｗｌａｒｋ．ｃｏｍ ───── http://www.cowlark.com ───── │ │ life←{ ↑1 ⍵∨.^3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵ } │ --- Conway's Game Of Life, in one line of APL
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