Function boostRingFromVertices

src/utilities/geometry/Intersection.cpp:387–418

convert vertices to a boost ring, all vertices must lie on z = 0 plane

// convert vertices to a boost ring, all vertices must lie on z = 0 plane
boost::optional<BoostRing> boostRingFromVertices(const std::vector<Point3d>& vertices, std::vector<Point3d>& allPoints, double tol) {
  if (vertices.size() < 3) {
    return boost::none;
  }

  BoostRing ring;
  for (const Point3d& vertex : vertices) {

    // should all have zero z coordinate now
    const double z = vertex.z();
    if (std::abs(z) > tol) {
      LOG_FREE(Error, "utilities.geometry.boostRingFromVertices", "All points must be on z = 0 plane");
      return boost::none;
    }

    // use helper method which combines close points
    boost::geometry::append(ring, boostPointFromPoint3d(vertex, allPoints, tol));
  }

  // close polygon, use helper method which combines close points
  boost::geometry::append(ring, boostPointFromPoint3d(vertices[0], allPoints, tol));

  //boost::geometry::correct(ring);

  boost::optional<double> testArea = boost::geometry::area(ring);
  if (!testArea || (*testArea < 0)) {
    // DLM: we could offer to reverse these vertices here but that might not be the best idea
    return boost::none;
  }

  return ring;
}

boost::optional<BoostRing> nonIntersectingBoostRingFromVertices(const std::vector<Point3d>& polygon, std::vector<Point3d>& allPoints, double tol) {
  boost::optional<BoostRing> result = boostRingFromVertices(polygon, allPoints, tol);