CODEWITHSUNDEEP
c++windowsopengl
user10692448
user10692448

Reputation:

Error while loading opengl functions without a loading library

I don't really know what i'm doing wrong. I'm not using a loading library so I can have more control over my code. I am using windows os.

#include <gl/GL.h>
#include <windows.h>

typedef BOOL(WINAPI wglSwapInterval_t) (int interval);
static wglSwapInterval_t* wglSwapInterval;

#ifndef GLAPI
#define GLAPI extern
#endif

#ifndef APIENTRYP
#define APIENTRYP APIENTRY *
#endif

#define GL_VERTEX_SHADER 0x8B31
#define GL_FRAGMENT_SHADER 0x8B30

typedef GLuint(APIENTRYP PFNGLCREATEPROGRAMPROC) (void);
PFNGLCREATEPROGRAMPROC glCreateProgram = (PFNGLCREATEPROGRAMPROC)wglGetProcAddress("glCreateProgram");

Error:

(5): error C2086: 'wglSwapInterval_t (__stdcall *__stdcall wglSwapInterval)': redefinition
(5): note: see declaration of 'wglSwapInterval'
(19): error C2374: 'glCreateProgram': redefinition; multiple initialization
(19): note: see declaration of 'glCreateProgram'

Upvotes: 0

Views: 265

Answers (1)

frogatto
frogatto

Reputation: 29285

  • Error C2086 says that you have defined wglSwapInterval multiple times.

  • Error C2374 says that you have defined and initialized glCreateProgram multiple times.

The common reason for such problems is including an unguarded .h file more than once in a single .cpp file directly or indirectly (i.e. included in another file which itself is included in the current file).

To avoid such problems, always put #ifndef or #pragma once in your .h files as the include guard.

Upvotes: 1

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