Function removeSpikesEx

src/utilities/geometry/Intersection.cpp:138–220

Cleans a polygon by shrinking and expanding. Can return multiple polygons

// Cleans a polygon by shrinking and expanding. Can return multiple polygons
std::vector<BoostPolygon> removeSpikesEx(const BoostPolygon& polygon) {

  //const double buffer_distance = 1.0;
  //const int points_per_circle = 36;
  constexpr bool extraLogging = false;
  // The amount to shrink and expand the polygons by
  constexpr double offsetBy = 0.01;
  constexpr double tol = offsetBy;
  // Sets the limit to how far miters are extended for sharp corners
  constexpr double mitreLimit = 100;
  const boost::geometry::strategy::buffer::distance_symmetric<coordinate_type> expand(offsetBy * scaleBy);
  const boost::geometry::strategy::buffer::distance_symmetric<coordinate_type> shrink(-offsetBy * scaleBy);
  const boost::geometry::strategy::buffer::join_miter join_strategy(mitreLimit * scaleBy);
  const boost::geometry::strategy::buffer::end_flat end_strategy;
  const boost::geometry::strategy::buffer::side_straight side_strategy;
  const boost::geometry::strategy::buffer::point_circle point_strategy;

  BoostMultiPolygon resultExpand;
  BoostMultiPolygon resultShrink;
  BoostMultiPolygon result;

  // Used for extra logging
  BoostMultiPolygon shrinkExpand;
  // cppcheck-suppress knownConditionTrueFalse
  if constexpr (extraLogging) {
    shrinkExpand.push_back(polygon);
  }

  // Shrink the polygon
  boost::geometry::buffer(polygon, resultShrink, shrink, side_strategy, join_strategy, end_strategy, point_strategy);
  // cppcheck-suppress knownConditionTrueFalse
  if constexpr (extraLogging) {
    shrinkExpand.push_back(resultShrink[0]);
  }

  // Inflate the polygon
  boost::geometry::buffer(resultShrink, resultExpand, expand, side_strategy, join_strategy, end_strategy, point_strategy);
  // cppcheck-suppress knownConditionTrueFalse
  if constexpr (extraLogging) {
    shrinkExpand.push_back(resultExpand[0]);
  }

  // Very small tolerance to remove artifacts from the inflate
  constexpr double tol1 = 0.001;
  boost::geometry::simplify(resultExpand, result, tol1 * scaleBy);
  // cppcheck-suppress knownConditionTrueFalse
  if constexpr (extraLogging) {
    shrinkExpand.push_back(result[0]);
    LOG_FREE(Debug, "Shrink/Expand", shrinkExpand);
  }

  std::vector<BoostPolygon> solution;
  if (result.empty()) {
    // There's no result because the polygon was completely removed so return nothing
    return solution;
  } else if (result.size() == 1 && result[0].outer().size() == polygon.outer().size()) {
    // Number of vertices didn't change so no spikes were removed
    solution.push_back(polygon);