al_get_opengl_texture - Allegro 5 API

       Returns the OpenGL texture id internally used by the given bitmap if it uses one, else 0.

       Example:

              bitmap = al_load_bitmap("my_texture.png");
              texture = al_get_opengl_texture(bitmap);
              if (texture != 0)
                  glBindTexture(GL_TEXTURE_2D, texture);

Allegro reference manual                                                          al_get_opengl_texture(3alleg5)

       al_get_opengl_texture - Allegro 5 API

              #include <allegro5/allegro_opengl.h>

              GLuint al_get_opengl_texture(ALLEGRO_BITMAP *bitmap)