The HSV color scheme

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The HSV color scheme consists of three values:

  • Hue (base color): between 0 and 360
  • Saturation (purity): between 0 and 1
  • Value (brightness): between 0 and 1

Here, you can experiment with these values.

The underlying JavaScript code

var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-4,4,4,-4], keepaspectratio:true});
var H = brd.create('slider',[[-3,3.5],[2,3.5],[0,1,360]], {name:'H',fillColor:'black',strokeColor:'black'});
var S = brd.create('slider',[[-3,3],[2,3],[0,1,1]], {name:'S',fillColor:'black',strokeColor:'black'});
var V = brd.create('slider',[[-3,2.5],[2,2.5],[0,1,1]], {name:'V',fillColor:'black',strokeColor:'black'});
        
var r1 = 2;
var r2 = 1/4.75;
var lambda = 8;

var c1 = brd.create('curve',[
          function(t){return r1*Math.sin(t)+r2*Math.sin(lambda*t);},
          function(t){return r1*Math.cos(t)+r2*Math.cos(lambda*t)-0.2;},
          0, 2*Math.PI],
          {fillcolor:function(){ return JXG.hsv2rgb(H.Value(),S.Value(),V.Value()); },
           highlightFillcolor:function(){ return JXG.hsv2rgb(H.Value(),S.Value(),V.Value()); },
           strokeColor:'black',strokeWidth:3,gradient:'radial',gradientsecondcolor:'white'});

var c2 = brd.create('curve',[
          function(t){return Math.sin(t);},
          function(t){return Math.cos(t)-0.2;},
          0, 2*Math.PI],
          {fillcolor:function(){ return JXG.hsv2rgb(180+H.Value(),S.Value(),V.Value()); },
           highlightFillcolor:function(){ return JXG.hsv2rgb(180+H.Value(),S.Value(),V.Value()); },
           strokewidth:3,
           strokeColor:'black',gradient:'linear'});
var t = brd.create('text', [2,-3, function(){ return 'RGB='+JXG.hsv2rgb(H.Value(),S.Value(),V.Value());}],
                   {fontSize:32});

External links