h (PLFLT(3plplot), input)
Hue in degrees (0.0-360.0) on the color cylinder.
l (PLFLT(3plplot), input)
Lightness expressed as a fraction (0.0-1.0) of the axis of the color cylinder.
s (PLFLT(3plplot), input)
Saturation expressed as a fraction (0.0-1.0) of the radius of the color cylinder.
p_r (PLFLT_NC_SCALAR(3plplot), output)
Returned value of the red intensity (0.0-1.0) of the color.
p_g (PLFLT_NC_SCALAR(3plplot), output)
Returned value of the green intensity (0.0-1.0) of the color.
p_b (PLFLT_NC_SCALAR(3plplot), output)
Returned value of the blue intensity (0.0-1.0) of the color.