code: function colorWheel( WheelPos ){
          var r,g,b;
          WheelPos = 255 - WheelPos;
  
          if ( WheelPos < 85 ) {
              r = 255 - WheelPos * 3;
              g = 0;
              b = WheelPos * 3;
          } else if (WheelPos < 170) {
              WheelPos -= 85;
              r = 0;
              g = WheelPos * 3;
              b = 255 - WheelPos * 3;
          } else {
              WheelPos -= 170;
              r = WheelPos * 3;
              g = 255 - WheelPos * 3;
              b = 0;
          }
          // returns a string with the rgb value to be used as the parameter
          return "rgb(" + r +"," + g + "," + b + ")";
      }
docs: Input a value 0 to 255 to get a color value. The colours are a transition r - g - b - back to r.