gistfile1.js

// Fast Polyline
var fastTrack;
var fastWaypoints = Array();
var fastDistance = 0;

var optimize = function(turnpoints, google, map) {
  var headings = Array();
  fastWaypoints = Array();

  for (var i = 0; i < turnpoints.length; i++) {
    // For all turnpoint excpet the last one.
    if (i < turnpoints.length - 1) {
      // Getting the heading.
      var heading = google.maps.geometry.spherical.computeHeading(turnpoints[i].latLng, turnpoints[i + 1].latLng);
      // Unsure heading is always positive.
      if (heading < 0) heading += 360;
      if (headings.length >= 1) {
        // Switch first heading from 180°.
        var pastHeading = headings[i- 1];
        // We need to catch the right angle !!!
        if (pastHeading > heading) {
          pastHeading -= 180;
        } else {
          pastHeading += 180;
        }
        // Now we can get the average heading. (Bisectrix).
        var middleHeading = (pastHeading + heading) / 2;
        // Offset from the center to the radius to get the intermediary point.
        var fastPoint = google.maps.geometry.spherical.computeOffset(turnpoints[i].latLng, turnpoints[i].radius, middleHeading);
      }
    }
    else {
      // For the first point just offset form the center to its radius following the heading of next turnpoint.
      var fastPoint = google.maps.geometry.spherical.computeOffset(turnpoints[i].latLng, turnpoints[i].radius, heading);
    }
    headings.push(heading);
    fastWaypoints.push(fastPoint);
    incrementDistance(google, fastWaypoints, 'fast');
  }
}
 
// For the last point just reverse the last heading from the center and offset to the radius.
if (headings.length >= 1) {
  var newPoint = google.maps.geometry.spherical.computeOffset(turnpoints[i - 1].latLng, turnpoints[i - 1].radius, headings[headings.length - 1] - 180);
  fastWaypoints.push(newPoint);
  incrementDistance(google, fastWaypoints, 'fast');
}

if (fastTrack) fastTrack.setMap(null);
fastTrack = new google.maps.Polyline({
  path: fastWaypoints,
  geodesic: true,
  strokeColor: '#FF0000',
  strokeOpacity: 1.0,
  strokeWeight: 2,
  map:map
)};