Circle: Difference between revisions
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=== Dynamic fill-opacity === | === Dynamic fill-opacity === | ||
We can make the fill-opacity dynamic and make it | We can make the fill-opacity dynamic and make it dependent on the position of "B", i.e. the JavaScript variable "p2". | ||
<source lang="javascript"> | <source lang="javascript"> |
Revision as of 20:53, 17 September 2008
Circle through two points
One possibility to construct a circle is to give its center and a point defining its radius. Lets construct two points "A" and "B".
var b = JXG.JSXGraph.initBoard('jxgbox', {originX: 200, originY: 100, unitX: 50, unitY: 50});
var p1 = board.createElement('point',[0,0], {name:'A',style:6});
var p2 = board.createElement('point',[2,-1], {name:'B',style:6});
Then we construct a circle through "A" and "B". The setting of a new color and changing the stroke-width is not necessary.
var ci = brd.createElement('circle',["A","B"], {strokeColor:'#00ff00',strokeWidth:2});
Generally it is better to use JavaScript variables and not Geometry-Element names when constructing. Now, we do the same examples with JavaScript variables. To show other variations, we use a dashed stroke style and set a fill color.
var ci2 = brd2.createElement('circle',[p1,p2],
{strokeWidth:3, dash:2, fillColor:'#ffff00', fillOpacity:0.3});
Dynamic fill-opacity
We can make the fill-opacity dynamic and make it dependent on the position of "B", i.e. the JavaScript variable "p2".
var ci3 = brd3.createElement('circle',[p1,p2],
{strokeWidth:1, fillColor:'#555500', fillOpacity:function(){ return p2.X()*0.25;} });