assets/script.js
// any selected arcs from their current angle to the specified new angle.
any selected arcs from their current angle to the specified new angle.
any selected arcs from their current angle to the specified new angle .
function arcTween(transition, newAngle) {
  transition.attrTween("d", function(d) {
    var interpolate = d3.interpolate(d.endAngle, newAngle);
    return function(t) {
       Note that the interpolated angle is written into the element's bound
       data object! This is important: it means that if the transition were
       interrupted, the data bound to the element would still be consistent
       with its appearance. Whenever we start a new arc transition, the
       correct starting angle can be inferred from the data.
      d.endAngle = interpolate(t);
       Lastly, compute the arc path given the updated data! In effect, this
       transition uses data-space interpolation: the data is interpolated
       (that is, the end angle) rather than the path string itself.
       Interpolating the angles in polar coordinates, rather than the raw path
       string, produces valid intermediate arcs during the transition.
      return arc(d);
    };
  });
}
function arcTween ( transition , newAngle ) { transition . attrTween ( "d" , function ( d ) { var interpolate = d3 . interpolate ( d . endAngle , newAngle ) ; return function ( t ) { d . endAngle = interpolate ( t ) ; return arc ( d ) ; } ; } ) ; }
any selected arcs from their current angle to the specified new angle.
any selected arcs from their current angle to the specified new angle .
// The function passed to attrTween is invoked for each selected element when // the transition starts, and for each element returns the interpolator to use // over the course of transition. This function is thus responsible for // determining the starting angle of the transition (which is pulled from the // element's bound datum, d.endAngle), and the ending angle (simply the // newAngle argument to the enclosing function). // To interpolate between the two angles, we use the default d3.interpolate. // (Internally, this maps to d3.interpolateNumber, since both of the // arguments to d3.interpolate are numbers.) The returned function takes a // single argument t and returns a number between the starting angle and the // ending angle. When t = 0, it returns d.endAngle; when t = 1, it returns // newAngle; and for 0 < t < 1 it returns an angle in-between. // The return value of the attrTween is also a function: the function that // we want to run for each tick of the transition. Because we used // attrTween("d"), the return value of this last function will be set to the // "d" attribute at every tick. (It's also possible to use transition.tween // to run arbitrary code for every tick, say if you want to set multiple // attributes from a single function.) The argument t ranges from 0, at the // start of the transition, to 1, at the end. // Calculate the current arc angle based on the transition time, t. Since // the t for the transition and the t for the interpolate both range from // 0 to 1, we can pass t directly to the interpolator. // // Note that the interpolated angle is written into the element's bound // data object! This is important: it means that if the transition were // interrupted, the data bound to the element would still be consistent // with its appearance. Whenever we start a new arc transition, the // correct starting angle can be inferred from the data. // Lastly, compute the arc path given the updated data! In effect, this // transition uses data-space interpolation: the data is interpolated // (that is, the end angle) rather than the path string itself. // Interpolating the angles in polar coordinates, rather than the raw path // string, produces valid intermediate arcs during the transition.