al_get_opengl_texture - Allegro 5 API
  
  - 
    #include <allegro5/allegro_opengl.h>
GLuint al_get_opengl_texture(ALLEGRO_BITMAP *bitmap)
    
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);