al_get_bitmap_depth - Allegro 5 API

       Return the depthbuffer depth used by this bitmap if it is used with al_set_target_bitmap(3alleg5).

       al_get_bitmap_depth - Allegro 5 API

       5.2.1

              [UnstableAPI]: This is an experimental feature and currently only works for the OpenGL backend.

Allegro reference manual                                                            al_get_bitmap_depth(3alleg5)

              #include <allegro5/allegro.h>

              int al_get_bitmap_depth(ALLEGRO_BITMAP *bitmap)