Allegro Version 4.9.2 (SVN) |
opengl/ extensions.cSummary
al_opengl_version
Returns the OpenGL version number of the client (the computer the program is running on), for the current DISPLAY. “1.0” is returned as 1.0, “1.2.1” is returned as 1.21, and “1.2.2” as 1.22, etc. A valid OpenGL context must exist for this function to work, which means you may \b not call it before al_create_display(). al_is_opengl_extension_supported
This function is a helper to determine whether an OpenGL extension is available on the current display or not. Exampleint packedpixels = al_is_opengl_extension_supported("GL_EXT_packed_pixels"); If packedpixels is TRUE then you can safely use the constants related to the packed pixels extension. Parameters
ReturnsTRUE if the extension is available FALSE otherwise. al_get_opengl_proc_address
Helper to get the address of an OpenGL symbol ExampleHow to get the function glMultiTexCoord3fARB that comes with ARB’s Multitexture extension : // define the type of the function If glMultiTexCoord3fARB is not NULL then it can be used as if it has been defined in the OpenGL core library. Note that the use of the ALLEGRO_DEFINE_PROC_TYPE macro is mandatory if you want your program to be portable. Parameters
ReturnsA pointer to the symbol if available or NULL otherwise. al_get_opengl_extension_list
Returns the list of OpenGL extensions supported by Allegro, for the current display. Allegro will keep information about all extensions it knows about in a structure returned by al_get_opengl_extension_list. For exampleif (al_get_opengl_extension_list()->ALLEGRO_GL_ARB_multitexture) { use it } The extension will be set to true if available for the current display and false otherwise. This means to use the definitions and functions from an OpenGL extension, all you need to do is to check for it as above at run time, after acquiring the OpenGL display from Allegro. Under Windows, this will also work with WGL extensions, and under Unix with GLX extensions. In case you want to manually check for extensions and load function pointers yourself (say, in case the Allegro developers did not include it yet), you can use the al_is_opengl_extension_supported and al_get_opengl_proc_address functions instead. |
Returns the OpenGL version number of the client (the computer the program is running on), for the current DISPLAY.
float al_opengl_version( void )
This function is a helper to determine whether an OpenGL extension is available on the current display or not.
int al_is_opengl_extension_supported( AL_CONST char * extension )
Helper to get the address of an OpenGL symbol
void *al_get_opengl_proc_address( AL_CONST char * name )
Returns the list of OpenGL extensions supported by Allegro, for the current display.
ALLEGRO_OGL_EXT_LIST *al_get_opengl_extension_list( void )