plrgbhls: Convert RGB color to HLS

plrgbhls (r, g, b, p_h, p_l, p_s);

Convert RGB color coordinates to HLS

r (PLFLT, output)

Red intensity (0.0-1.0) of the colour

g (PLFLT, output)

Green intensity (0.0-1.0) of the colour

b (PLFLT, output)

Blue intensity (0.0-1.0) of the colour

p_h (PLFLT *, input)

Pointer to hue, in degrees on the colour cone (0.0-360.0)

p_l (PLFLT *, input)

Pointer to lightness, expressed as a fraction of the axis of the colour cone (0.0-1.0)

p_s (PLFLT *, input)

Pointer to saturation, expressed as a fraction of the radius of the colour cone (0.0-1.0)