Returns the address of the GL function proc, or NULL if the function is not found. If the GL library is loaded at runtime, with SDL_GL_LoadLibrary, then all GL functions must be retrieved this way. Usually this is used to retrieve function pointers to OpenGL extensions.
typedef void (*GL_ActiveTextureARB_Func)(unsigned int);
+GL_ActiveTextureARB_Func glActiveTextureARB_ptr = 0;
+int has_multitexture=1;
+.
+.
+.
+/* Get function pointer */
+glActiveTextureARB_ptr=(GL_ActiveTextureARB_Func) SDL_GL_GetProcAddress("glActiveTextureARB");
+
+/* Check for a valid function ptr */
+if(!glActiveTextureARB_ptr){
+ fprintf(stderr, "Multitexture Extensions not present.\n");
+ has_multitexture=0;
+}
+.
+.
+.
+.
+if(has_multitexture){
+ glActiveTextureARB_ptr(GL_TEXTURE0_ARB);
+ .
+ .
+}
+else{
+ .
+ .
+}