$ryb-interpolation: #FF0000 #FF4900 #FF7400 #FF9200 #FFAA00 #FFBF00 #FFD300 #FFE800 #FFFF00 #CCF600 #9FEE00 #67E300 #00CC00 #00AF64 #009999 #0B61A4 #1240AB #1B1BB3 #3914AF #530FAD #7109AA #A600A6 #CD0074 #E40045;

// RYB color interpolation
@function find-ryb($hue) {

  // remove units on $hue
  @if unit($hue) == deg { $hue: $hue / 1deg; }

  // return an interpolated hue
  @return hue(cs-interpolate($hue));
}

// Find the RYB hue instead of RGB hue of a color.
// slow dumb loop at the moment.
@function ryb-hue($color) {

  // find offset
  $hue: find-ryb(hue($color)) - hue($color);

  // apply the offset difference
  $hue: hue($color) - $hue;

  // Make within the range of 360 if not already.
  @while $hue >= 360deg {
    $hue: $hue - 360;
  }
  @while $hue < 0deg {
    $hue: $hue + 360;
  }

  @return $hue;
}

// Changes the hue of a color.
@function ryb-adjust-hue($color, $degrees) {

  // Convert precentag to degrees.
  @if unit($degrees) == "%" {
    $degrees: 360 * ($degrees / 100%);
  }

  // Start at the current hue and loop in the adjustment.
  $hue-adjust: (ryb-hue($color) + $degrees) / 1deg;

  $lightness: lightness($color);
  $saturation: saturation($color);

  // Set hue of new color
  $new-color: set-hue(red, hue(cs-interpolate($hue-adjust)));

  // Add back lightness
  $new-color: set-lightness($new-color, $lightness);

  // Add back saturation
  $new-color: set-saturation($new-color, $saturation);

  @return $new-color;
}

@function ryba($red, $yellow, $blue, $alpha) {
  $hue: 0;
  $saturation: 0;
  $lightness: percentage(($red + $yellow + $blue) / (255 * 3));
  @if $red == $yellow and $yellow == $blue {
    @return hsla(0, 0, $lightness, $alpha);
  }
  @if $red >= $yellow and $red >= $blue {
    $hue: 0;
  }
  @elseif $yellow >= $red and $yellow >= $blue {
    $hue: 360 / 3;
  }
  @elseif $blue >= $red and $blue >= $yellow {
    $hue: 360 / 3 * 2;
  }
  @return hsla(hue(cs-interpolate($hue)), 100%, 50%, 1);
}

@function ryb($red, $yellow, $blue) {
  @return ryba($red, $yellow, $blue, 1);
}

@function set-ryb-hue($color, $hue) {
  @return hsla(hue(cs-interpolate($hue)), saturation($color), lightness($color), alpha($color));
}

// Returns the complement of a color.
@function ryb-complement($color) {
  @return ryb-adjust-hue($color, 180deg);
}

// Returns the inverse of a color.
@function ryb-invert($color) {
  @return ryb-adjust-hue(hsl(hue($color), saturation(invert($color)), lightness(invert($color))), 180deg);
}