al_color_lch - Allegro 5 API
Return an ALLEGRO_COLOR(3) structure from CIE LCH values. LCH colors are very
similar to HSL, with the same meaning of L and H and C corresponding to S.
However LCH is more visually uniform. Furthermore, this function expects the
angle for H in radians and not in degree.
ALLEGRO_COLOR al_color_lch(float l, float c, float h)
The CIE LCH color space is a cylindrical representation of the
L*a*b* color space. The L component is the same and C and H are computed
C = sqrt(a * a + b * b)
H = atan2(b, a)