al_color_xyy - Allegro 5 API

       Return  an  ALLEGRO_COLOR(3alleg5)  structure from xyY values.  The Y component in the xyY color space is
       the same as the Y in XYZ.

       However the x and y values are computed from XYZ like this:

              x = X / (X + Y + Z)
              y = Y / (X + Y + Z)

       al_color_xyy - Allegro 5 API

al_color_xyy_to_rgb(3alleg5), al_color_rgb_to_xyy(3alleg5)

Allegro reference manual                                                                   al_color_xyy(3alleg5)

       5.2.3

              #include <allegro5/allegro_color.h>

              ALLEGRO_COLOR al_color_xyy(float x, float y, float y2)