lineIntersect function

FeatureCollection<Point> lineIntersect(GeoJSONObject line1, GeoJSONObject line2, { bool removeDuplicates = true, bool ignoreSelfIntersections = false, })

Takes any LineString or Polygon and returns the intersecting Point. removeDuplicates (default true) removes duplicate intersections, ignoreSelfIntersections (default false) ignores self-intersections on input features Returns a FeatureCollection<Point> containing point(s) that intersect both example:

var line1 = LineString(coordinates:[
   Position.of([126, -11]),
   Position.of([129, -21]),
 ]);
var line2 = LineString(coordinates:[
 Position.of([123, -18]),
 Position.of([131, -14]),
 ]);
var intersects = lineIntersect(line1, line2);
//addToMap
var addToMap = [line1, line2, intersects]

Implementation

FeatureCollection<Point> lineIntersect(
  GeoJSONObject line1,
  GeoJSONObject line2, {
  bool removeDuplicates = true,
  bool ignoreSelfIntersections = false,
}) {
  var features = <Feature>[];
  if (line1 is FeatureCollection) {
    features.addAll(line1.features);
  } else if (line1 is Feature) {
    features.add(line1);
  } else if (line1 is LineString ||
      line1 is Polygon ||
      line1 is MultiLineString ||
      line1 is MultiPolygon) {
    features.add(Feature(geometry: line1 as GeometryType));
  }

  if (line2 is FeatureCollection) {
    features.addAll(line2.features);
  } else if (line2 is Feature) {
    features.add(line2);
  } else if (line2 is LineString ||
      line2 is Polygon ||
      line2 is MultiLineString ||
      line2 is MultiPolygon) {
    features.add(Feature(geometry: line2 as GeometryType));
  }

  var intersections = sweeplineIntersections(
      FeatureCollection(features: features), ignoreSelfIntersections);
  Set unique = {};
  if (removeDuplicates) {
    for (var intersection in intersections) {
      unique.add(intersection);
    }
  }
  return FeatureCollection(
    features: (removeDuplicates ? unique.toList() : intersections)
        .map(
          (r) => Feature(
            geometry: Point(coordinates: r),
          ),
        )
        .toList(),
  );
}