interpolate method

InterpolatedResult interpolate(dynamic controllerValue, dynamic animValue, dynamic interpolateBetweenPoints)

Implementation

InterpolatedResult interpolate( controllerValue, animValue, interpolateBetweenPoints ) {
  var thisPoint;

  for( var c=lastPointIndex; c < points.length ; c++ ) {
    if( animValue >= pointDistanceSteps[c].distance ) {
      /// Our animation is past the next point, so add it in
      /// but remove any interpolated point that we were using
      if( interpolatedPoint != null ) {
        builtPoints.removeLast(); // dont nec need the interpolated point any more
        interpolatedPoint = null;
      }

      thisPoint = LatLng(points[c].latitude, points[c].longitude);
      builtPoints.add(thisPoint);
      lastPointIndex = c+1;

    } else {

      /// only need this if we want to draw inbetween points...
      /// use our point steps and interpolate
      if( interpolateBetweenPoints ) {

        var lastPerc = pointDistanceSteps[c - 1].percent;
        var nextPerc = pointDistanceSteps[c].percent;

        if (nextPerc == null) break;

        var perc = (controllerValue - lastPerc) / ///  swap this around with not 0-1 and get rid of tweener ?
            (nextPerc - lastPerc);

        var intermediateLat = (points[c].latitude -
            points[c - 1].latitude) * perc + points[c - 1].latitude;
        var intermediateLon = (points[c].longitude -
            points[c - 1].longitude) * perc + points[c - 1].longitude;


        interpolatedPoint = LatLng(
            intermediateLat, intermediateLon); // last tail point

        if (builtPoints.length > c) {
          builtPoints[c] = interpolatedPoint!;
        } else {
          builtPoints.add(interpolatedPoint!);
        }
      }

      thisPoint = interpolatedPoint;
      break;
    }
  }

  if( thisPoint == null ) {
    thisPoint = LatLng(points[lastPointIndex - 1].latitude,
        points[lastPointIndex - 1].longitude);
  }

  double angle = 0.0;
  if(_previousPoint != null)
    if(thisPoint != null) {
      angle = -atan2(thisPoint.latitude - _previousPoint?.latitude,
        thisPoint.longitude - _previousPoint?.longitude ) - 4.7128 ;
  }

  // We do this in case we're not interpolating visually otherwise
  // point and prev point are the same most of the time
  if(_lastAngle == null) _lastAngle = angle;
  if(thisPoint != _previousPoint) _lastAngle = angle;
  //if((_lastAngle == null) || (thisPoint != _previousPoint)) _lastAngle = angle;

  _previousPoint = thisPoint;

  return InterpolatedResult(point: thisPoint, angle: _lastAngle, animValue: animValue,
      controllerValue: controllerValue, builtPoints: builtPoints);
}