Difference between revisions of "The HSV color scheme"

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Line 5: Line 5:
 
Here, you can experiment with these values.
 
Here, you can experiment with these values.
 
<jsxgraph width=600 height=500>
 
<jsxgraph width=600 height=500>
var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-2,4,8,-4]});
+
        var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-4,4,4,-4]});
var H = brd.createElement('slider',[[0,3.5],[5,3.5],[0,1,360]], {name:'H'});
+
        var H = brd.createElement('slider',[[-3,3.5],[2,3.5],[0,1,360]], {name:'H',fillColor:'black',strokeColor:'black'});
var S = brd.createElement('slider',[[0,3],[5,3],[0,1,1]], {name:'S'});
+
        var S = brd.createElement('slider',[[-3,3],[2,3],[0,1,1]], {name:'S',fillColor:'black',strokeColor:'black'});
var V = brd.createElement('slider',[[0,2.5],[5,2.5],[0,1,1]], {name:'V'});
+
        var V = brd.createElement('slider',[[-3,2.5],[2,2.5],[0,1,1]], {name:'V',fillColor:'black',strokeColor:'black'});
var rct = brd.createElement('curve',[[-1,-1,5,5,-1],[-2,2,2,-2,-2]],
+
       
                {strokeColor:'black',  
+
        var r1 = 2;
                  fillcolor:function(){ return JXG.hsv2rgb(H.Value(),S.Value(),V.Value()); }
+
        var r2 = 1/4.75;
                 }
+
        var lambda = 8;
          );
+
        var phi = 0;
 +
var c = brd.createElement('curve',[
 +
          function(t){return r1*Math.sin(t)+r2*Math.sin(lambda*t+phi);},
 +
          function(t){return r1*Math.cos(t)+r2*Math.cos(lambda*t+phi)-0.5;},
 +
          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'});
 +
         
 +
        var p = brd.createElement('point',[0,-0.5],{visible:false});
 +
        var ci = brd.createElement('circle',[p,1],  
 +
                {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'
 +
                });            
 
</jsxgraph>
 
</jsxgraph>
  

Revision as of 17:04, 24 September 2009

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

<jsxgraph width=600 height=500>
var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-2,4,8,-4]});
var H = brd.createElement('slider',[[0,3.5],[5,3.5],[0,1,360]], {name:'H'});
var S = brd.createElement('slider',[[0,3],[5,3],[0,1,1]], {name:'S'});
var V = brd.createElement('slider',[[0,2.5],[5,2.5],[0,1,1]], {name:'V'});
var rct = brd.createElement('curve',[[-1,-1,5,5,-1],[-2,2,2,-2,-2]],
                 {strokeColor:'black', 
                  fillcolor:function(){ return JXG.hsv2rgb(H.Value(),S.Value(),V.Value()); }
                 }
          );
</jsxgraph>

External links