al_invert_transform - Allegro 5 API

       Inverts  the  passed  transformation.   If  the transformation is nearly singular (close to not having an
       inverse) then the returned transformation may be invalid.  Use al_check_inverse(3alleg5) to ascertain  if
       the transformation has an inverse before inverting it if you are in doubt.

       Parameters:

       • trans - Transformation to invert

         Note: Allegro’s transformation inversion functions work correctly only with 2D transformations.

       al_invert_transform - Allegro 5 API

al_check_inverse(3alleg5)

Allegro reference manual                                                            al_invert_transform(3alleg5)

              #include <allegro5/allegro.h>

              void al_invert_transform(ALLEGRO_TRANSFORM *trans)