Difference between revisions of "Bezier curves"

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Line 10: Line 10:
  
 
var col = 'red';  
 
var col = 'red';  
p.push(brd.createElement('point',[2,1],{strokeColor:col,fillColor:col,name:(p.length+1)}));        // data point
+
p.push(brd.createElement('point',[2,1],{strokeColor:col,fillColor:col}));        // data point
 
col = 'blue';  
 
col = 'blue';  
p.push(brd.createElement('point',[0.75,2.5],{strokeColor:col,fillColor:col,name:(p.length+1)}));  // control point
+
p.push(brd.createElement('point',[0.75,2.5],{strokeColor:col,fillColor:col}));  // control point
p.push(brd.createElement('point',[-0.3,0.3],{strokeColor:col,fillColor:col,name:(p.length+1)}));  // control point
+
p.push(brd.createElement('point',[-0.3,0.3],{strokeColor:col,fillColor:col}));  // control point
  
 
col = 'red';  
 
col = 'red';  
p.push(brd.createElement('point',[-3,1],{strokeColor:col,fillColor:col,name:(p.length+1)}));      // data point
+
p.push(brd.createElement('point',[-3,1],{strokeColor:col,fillColor:col}));      // data point
 
col = 'blue';  
 
col = 'blue';  
p.push(brd.createElement('point',[-0.75,-2.5],{strokeColor:col,fillColor:col,name:(p.length+1)})); // control point
+
p.push(brd.createElement('point',[-0.75,-2.5],{strokeColor:col,fillColor:col})); // control point
p.push(brd.createElement('point',[1.5,-2.8],{strokeColor:col,fillColor:col,name:(p.length+1)}));  // control point
+
p.push(brd.createElement('point',[1.5,-2.8],{strokeColor:col,fillColor:col}));  // control point
  
 
col = 'red';  
 
col = 'red';  
p.push(brd.createElement('point',[2,-0.5],{strokeColor:col,fillColor:col,name:(p.length+1)}));    // data point
+
p.push(brd.createElement('point',[2,-0.5],{strokeColor:col,fillColor:col}));    // data point
  
 
var c = brd.createElement('curve', JXG.Math.Numerics.bezier(p),  
 
var c = brd.createElement('curve', JXG.Math.Numerics.bezier(p),  
Line 31: Line 31:
 
   col = 'blue';  
 
   col = 'blue';  
 
   p.push(brd.createElement('point',[Math.random()*8-4,Math.random()*8-4],
 
   p.push(brd.createElement('point',[Math.random()*8-4,Math.random()*8-4],
           {strokeColor:col,fillColor:col,name:(p.length+1)})); // control point
+
           {strokeColor:col,fillColor:col})); // control point
 
   p.push(brd.createElement('point',[Math.random()*8-4,Math.random()*8-4],
 
   p.push(brd.createElement('point',[Math.random()*8-4,Math.random()*8-4],
           {strokeColor:col,fillColor:col,name:(p.length+1)}));  // control point
+
           {strokeColor:col,fillColor:col}));  // control point
 
   col = 'red';  
 
   col = 'red';  
 
   p.push(brd.createElement('point',[Math.random()*8-4,Math.random()*8-4],
 
   p.push(brd.createElement('point',[Math.random()*8-4,Math.random()*8-4],
           {strokeColor:col,fillColor:col,name:(p.length+1)}));    // data point
+
           {strokeColor:col,fillColor:col}));    // data point
 
   brd.unsuspendUpdate();
 
   brd.unsuspendUpdate();
 
};
 
};

Revision as of 08:16, 29 September 2009

The red points are connected by a cubic Bezier curve. The blue points are the control points.

The underlying JavaScript code

var brd = JXG.JSXGraph.initBoard('jxgbox',{boundingbox:[-4,4,4,-4],keepaspectratio:true,axis:true});

var p = [];

col = 'red'; 
p.push(brd.createElement('point',[2,1],{strokeColor:col,fillColor:col}));        // data point
col = 'blue'; 
p.push(brd.createElement('point',[0.75,2.5],{strokeColor:col,fillColor:col}));   // control point
p.push(brd.createElement('point',[-0.3,0.3],{strokeColor:col,fillColor:col}));   // control point

col = 'red'; 
p.push(brd.createElement('point',[-3,1],{strokeColor:col,fillColor:col}));       // data point
col = 'blue'; 
p.push(brd.createElement('point',[-0.75,-2.5],{strokeColor:col,fillColor:col})); // control point
p.push(brd.createElement('point',[1.5,-2.8],{strokeColor:col,fillColor:col}));   // control point

col = 'red'; 
p.push(brd.createElement('point',[2,-0.5],{strokeColor:col,fillColor:col}));     // data point

var c = brd.createElement('curve', JXG.Math.Numerics.bezier(p), {strokecolor:'blue', strokeOpacity:0.6, strokeWidth:5});