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Simple OpenGL Loader

An extensible, cross-platform, single-header C/C++ OpenGL loader library.

Usage

For Windows Win32 or Linux X11 applications, the simplest usage involves defining SOGL_MAJOR_VERSION, SOGL_MINOR_VERSIONand either SOGL_IMPLEMENTATION_WIN32 or SOGL_IMPLEMENTATION_X11 before including the simple-opengl-loader.h header file, and then calling sogl_loadOpenGL() after setting up an OpenGL context.

    #define SOGL_MAJOR_VERSION 4
    #define SOGL_MINOR_VERSION 5
    #define SOGL_IMPLEMENTATION_WIN32 /* or SOGL_IMPLEMENTATION_X11 */
    #include "simple-opengl-loader.h"

    int main() {

        /* Set up OpenGL context */
        
        sogl_loadOpenGL();

        /* Use OpenGL functions */
    }

It is recommended that simple-opengl-loader.h be the first include to prevent other OpenGL headers from setting up their own definitions.

Platform support is included for Windows Win32 and Linux X11 applications by defining the SOGL_IMPLEMENTATION_WIN32 or SOGL_IMPLEMENTATION_X11 constants, respectively. The SOGL_IMPLEMENTATION_X11 implementation requires the application be linked against libdl. See below to implement support for other platforms.

OpenGL extensions can be loaded by defining a constant of the format SOGL_<extension name> before including the simple-opengl-loader.h header.

    #define SOGL_MAJOR_VERSION 4
    #define SOGL_MINOR_VERSION 5
    #define SOGL_OVR_multiview
    #define SOGL_KHR_parallel_shader_compile
    #define SOGL_IMPLEMENTATION_WIN32
    #include "simple-opengl-loader.h"

Note that the loader makes no guarantees about OpenGL version or extension support. sogl_loadOpenGL() returns a boolean value indicating whether it was able to load all requested functions, and the function sogl_getFailures returns a null-terminated array of the names of the functions that failed to load (up to a maximum defined by SOGL_MAX_REPORTED_FAILURES).

    if (!sogl_loadOpenGL()) {
        const char **failures = sogl_getFailures();
        int i = 1;
        while (*failures) {
            fprintf(stderr, "Failed to load function %s\n", *failures);
            failures++;
        }
    }

Platform Support

Platform-specific logic is encapsulated in two functions sogl_loadOpenGLFunction() which takes the name of an OpenGL function as a null-terminated ASCII string and returns a pointer to the appropriate function, and sogl_cleanup(), which should perform any cleanup necessary after loading is complete, e.g. freeing library handles.

void *sogl_loadOpenGLFunction(const char *name);
void sogl_cleanup();

Implementations for these functions are provided out-of-the-box for Windows Win32 and Linux X11 applications (see above). Support for other platforms simply requires implementing these two functions for the target platform and defining the constant SOGL_IMPLEMENTATION instead of either of the platform-specific implementation constants.

    #define SOGL_MAJOR_VERSION 4
    #define SOGL_MINOR_VERSION 5
    #define SOGL_IMPLEMENTATION
    #include "simple-opengl-loader.h"

    void *sogl_loadOpenGLFunction(const char *name) {
        /* Custom function loader implementation */
    }
    
    void sogl_cleanup() {
        /* Custom cleanup implementation */ 
    }