Difference between revisions of "Bezier curves"

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(6 intermediate revisions by the same user not shown)
Line 10: Line 10:
  
 
var col = 'red';  
 
var col = 'red';  
p.push(brd.createElement('point',[2,1],{strokeColor:col,fillColor:col}));        // data point
+
p.push(brd.create('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}));  // control point
+
p.push(brd.create('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
+
p.push(brd.create('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}));      // data point
+
p.push(brd.create('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})); // control point
+
p.push(brd.create('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
+
p.push(brd.create('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}));    // data point
+
p.push(brd.create('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});  
+
var c = brd.create('curve', JXG.Math.Numerics.bezier(p),  
 +
              {strokecolor:'blue', strokeOpacity:0.6, strokeWidth:5});  
  
 
var addSegment = function() {
 
var addSegment = function() {
 
   brd.suspendUpdate();
 
   brd.suspendUpdate();
 
   col = 'blue';  
 
   col = 'blue';  
   p.push(brd.createElement('point',[Math.random()*8-4,Math.random()*8-4],
+
   p.push(brd.create('point',[Math.random()*8-4,Math.random()*8-4],
 
           {strokeColor:col,fillColor:col})); // control point
 
           {strokeColor:col,fillColor:col})); // control point
   p.push(brd.createElement('point',[Math.random()*8-4,Math.random()*8-4],
+
   p.push(brd.create('point',[Math.random()*8-4,Math.random()*8-4],
 
           {strokeColor:col,fillColor:col}));  // 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.create('point',[Math.random()*8-4,Math.random()*8-4],
 
           {strokeColor:col,fillColor:col}));    // data point
 
           {strokeColor:col,fillColor:col}));    // data point
 
   brd.unsuspendUpdate();
 
   brd.unsuspendUpdate();
Line 59: Line 60:
 
var p = [];
 
var p = [];
  
col = 'red';  
+
var col = 'red';  
p.push(brd.createElement('point',[2,1],{strokeColor:col,fillColor:col}));        // data point
+
p.push(brd.create('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}));  // control point
+
p.push(brd.create('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
+
p.push(brd.create('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}));      // data point
+
p.push(brd.create('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})); // control point
+
p.push(brd.create('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
+
p.push(brd.create('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}));    // data point
+
p.push(brd.create('point',[2,-0.5],{strokeColor:col,fillColor:col}));    // data point
 +
 
 +
var c = brd.create('curve', JXG.Math.Numerics.bezier(p),
 +
              {strokecolor:'blue', strokeOpacity:0.6, strokeWidth:5});
 +
 
 +
var addSegment = function() {
 +
  brd.suspendUpdate();
 +
  col = 'blue';
 +
  p.push(brd.create('point',[Math.random()*8-4,Math.random()*8-4],
 +
          {strokeColor:col,fillColor:col})); // control point
 +
  p.push(brd.create('point',[Math.random()*8-4,Math.random()*8-4],
 +
          {strokeColor:col,fillColor:col}));  // control point
 +
  col = 'red';
 +
  p.push(brd.create('point',[Math.random()*8-4,Math.random()*8-4],
 +
          {strokeColor:col,fillColor:col}));    // data point
 +
  brd.unsuspendUpdate();
 +
};
  
var c = brd.createElement('curve', JXG.Math.Numerics.bezier(p), {strokecolor:'blue', strokeOpacity:0.6, strokeWidth:5});  
+
var removeSegment = function() {
 +
  brd.suspendUpdate();
 +
 
 +
  if (p.length>4) {
 +
      brd.removeObject(p[p.length-1]);
 +
      brd.removeObject(p[p.length-2]);
 +
      brd.removeObject(p[p.length-3]);
 +
      p.splice(p.length-3,3);
 +
  }
 +
  brd.unsuspendUpdate();
 +
};
 
</source>
 
</source>
  
 
[[Category:Examples]]
 
[[Category:Examples]]
 
[[Category:Curves]]
 
[[Category:Curves]]
 +
[[Category:Interpolation]]

Latest revision as of 12:21, 29 July 2010

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 = [];

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

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

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

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

var addSegment = function() {
   brd.suspendUpdate();
   col = 'blue'; 
   p.push(brd.create('point',[Math.random()*8-4,Math.random()*8-4],
           {strokeColor:col,fillColor:col})); // control point
   p.push(brd.create('point',[Math.random()*8-4,Math.random()*8-4],
           {strokeColor:col,fillColor:col}));   // control point
   col = 'red'; 
   p.push(brd.create('point',[Math.random()*8-4,Math.random()*8-4],
           {strokeColor:col,fillColor:col}));     // data point
   brd.unsuspendUpdate();
};

var removeSegment = function() {
   brd.suspendUpdate();

   if (p.length>4) {
       brd.removeObject(p[p.length-1]);
       brd.removeObject(p[p.length-2]);
       brd.removeObject(p[p.length-3]);
       p.splice(p.length-3,3);
   }
   brd.unsuspendUpdate();
};