glbindify

glbindify

glbindify is a command line tool that generates C bindings for OpenGL, GLES2 (and higher), WGL, EGL, and GLX. The generated bindings can then be included in your projects, eliminating the need to link to a seperate loader library. The bindings are generated using XML API specifications mainained by khronos so only these XML files need to be updated to support new GL versions or extensions.

It supports generating bindings for core profile contexts only which substantially reduces the size of the bindings. The generated header file only exposes functions and enums for API versions and extensions you select at compile time, ensuring that your application does not accidentally aquire unwanted dependencies.

Command line usage

To generate bindings just specify the API name to glbindify where the API name is one of gl, gles2, wgl, egl, or glx. The tool will generate a source file and header file for the API in the current directory with the names glb-<api>.c and glb-<api>.h.

Example: Generate C bindings for OpenGL core profile contexts

glbindify -a gl

Using the bindings

After you have created your OpenGL context and made it current you must call

bool glb_<api>_init(int major_version, int minor_version)

If all functions for the requested version, excluding extensions, were found glb_<api>_init() will return true. Since glbindify mangles the GL function names with macros you must avoid including system OpenGL headers in files that also include the bindings.

Example:

#include "glb-glcore.h"
...
if (!glb_glcore_init(3, 3))
    exit(-1);
...
glDrawArrays(...);

Targeting specific versions

By default the generated header file will only expose functions and enums for the minimum version supported by glbindify. For OpenGL the minimum version is 3.2 core profile, for GLX it is 1.4, for GLES2 it is 2.0, and for WGL and EGL it is 1.0. To access functionality for later versions you must define a macro GLB_<API>_VERSION as an integer (major_version * 10) + minor_version where <API> is the name of the API in all caps.

Extensions

After initializing the bindings you may determine if an extension was successully loaded by checking its corresponding support flag. The support flags are named GLB_<extension name>. An extension support flag will be set to true if all functions for the extension were located. For OpenGL the extension string will also be checked. For WGL and glX the user should additionally check if the extension is supported on the specific screen or device context they are using. An extension's specific functions and enum values will only be exposed if the macro GLB_ENABLE_<extension name> is defined before glb-glcore.h is included.

Example: Checking for the GL_ARB_texture_storage extension

#define GLB_GL_VERSION 33
#define GLB_ENABLE_GL_ARB_texture_storage 1
#include "glb-glcore.h"
...
if (GLB_GL_ARB_texture_storage) {
    glTexStorage3D(...);
} else {
    ...
}

Using EGL

By default on GNU/Linux systems OpenGL bindings will be fetched with glXGetProcAddress(). If you want to use EGL you should define GLB_USE_EGL when you compile your GL bindings. This will cause eglGetProcAddress() to be called. The EGL API bindings will always be fetched via eglGetProcAddress().

GLES

GLES 2.0 and higher is supported by specifying gles2 as the API. GLES 3.0 and higher are supported through the GLES2 bindings by specifying a version number 3.0 or higher to glb_gles2_init().

Binding namespace

The naming of functions and macros in the bindings can be changed by passing a -n option to glbindify. When used, all instances of glb above will be changed to the selected namespace and all instances of GLB will be replaced with the upper case version of the selected namespace.

Example: Generating C bindings for OpenGL with a myapp namespace

glbindify -a gl -n myapp

Example: Using bindings with a myapp namespace

#include "myapp-glcore.h"
...
if (!myapp_glcore_init(3, 3))
    exit(-1);
...
glDrawArrays(...);

Building

glbindify requires only a C++98 compatible compiler to build and is known to build on GNU/Linux and Windows. On UNIX-like systems if gperf is available glbindify will generate a perfect hash map for extension checking at initialization time.

On UNIX-like systems glbindify can be built with its autotools build system:

./autogen.sh
./configure <options>
make
make install

On Windows glbindify can be built with the Visual Studio solution file in the windows folder. Note that the resulting executable must be run from the top level source directory.

The generated bindings will work on any supported platform regardless of the system they were built on. glbindify can also be built without the build system by compiling the sources with default options. For example:

g++ glbindify.cpp tinyxml2.cpp -o glbindify