Importing OpenGL functions

OpenGL OpenGL: Basic Coding
1

I imported gl.h and linked it in g++, but the compiler doesn 't recognize them.

Here is an error:
error: ‘glGetShaderInfoLog’ was not declared in this scope

Thanks

2

Which platform and OpenGL version?

On Linux, recent versions of the GL headers require you to define GL_GLEXT_PROTOTYPES if you want prototypes for OpenGL 2+ functions. Otherwise, they only provide typedefs for function pointers, e.g.

typedef void (APIENTRYP PFNGLGETSHADERINFOLOGPROC) (GLuint shader, GLsizei bufSize, GLsizei *length, GLchar *infoLog);

You can either declare a variable of that type and use glXGetProcAddress to obtain the pointer, or use a library such as GLEW to do it for you. If you use GLEW, then glew.h will provide the appropriate macro definitions, e.g.

#define glGetShaderInfoLog GLEW_GET_FUN(__glewGetShaderInfoLog)

Note that defining GL_GLEXT_PROTOTYPES will only work if libGL exports the symbols (this is a compile-time option). Otherwise you have to use glXGetProcAddress (directly or via a library such as GLEW).

1 Like