lsMarkVoidPoints.hpp

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#pragma once
 
#include <hrleSparseStarIterator.hpp>
 
#include <lsDomain.hpp>
#include <lsGraph.hpp>
 
namespace viennals {
 
using namespace viennacore;

enum struct VoidTopSurfaceEnum : unsigned {
  LEX_LOWEST = 0,
  LEX_HIGHEST = 1,
  LARGEST = 2,
  SMALLEST = 3
};

template <class T, int D> class MarkVoidPoints {
  using IndexType = std::size_t;
 
  SmartPointer<Domain<T, D>> domain = nullptr;
  bool reverseVoidDetection = false;
  bool saveComponents = false;
  bool detectLargestSurface = false;
 
  // two points are connected if they have the same sign
  static bool areConnected(const T &value1, const T &value2) {
    return (value1 >= 0) == (value2 >= 0);
  }
 
  std::vector<IndexType> static mergeComponentCounts(
      const std::vector<IndexType> &components,
      const std::vector<IndexType> &pointsPerComponent) {
    // find number of connected components after merge
    // TODO: the last element in the components vector is very likely
    // the highest index, so could just set it instead of checking all values
    unsigned highestIndex = 0;
    for (auto it : components) {
      if (highestIndex < it) {
        highestIndex = it;
      }
    }
 
    // merge pointsPerComponent according to the connected components
    std::vector<IndexType> pointsPerConnected;
    pointsPerConnected.resize(highestIndex + 1, 0);
    for (unsigned i = 0; i < components.size(); ++i) {
      pointsPerConnected[components[i]] += pointsPerComponent[i];
    }
 
    return pointsPerConnected;
  }
 
  IndexType
  calculateTopID(const std::vector<IndexType> &components,
                 const std::vector<IndexType> &pointsPerConnected) const {
    // check which component has the most points
    IndexType topId = 0;
    // use first component, which contains more than 0 points
    while (topId < pointsPerConnected.size() &&
           pointsPerConnected[topId] == 0) {
      ++topId;
    }
    for (unsigned i = topId + 1; i < pointsPerConnected.size(); ++i) {
      if ((pointsPerConnected[topId] < pointsPerConnected[i]) !=
          reverseVoidDetection) {
        topId = i;
      }
    }
 
    return topId;
  }
 
public:
  static constexpr char voidPointLabel[] = "VoidPointMarkers";
 
  MarkVoidPoints() = default;
 
  MarkVoidPoints(SmartPointer<Domain<T, D>> passedlsDomain,
                 bool passedReverseVoidDetection = false)
      : domain(passedlsDomain),
        reverseVoidDetection(passedReverseVoidDetection) {}
 
  void setLevelSet(SmartPointer<Domain<T, D>> passedlsDomain) {
    domain = passedlsDomain;
  }

  void setReverseVoidDetection(bool passedReverseVoidDetection) {
    reverseVoidDetection = passedReverseVoidDetection;
  }

  void setDetectLargestSurface(bool passedDetect) {
    detectLargestSurface = passedDetect;
  }

  void setVoidTopSurface(VoidTopSurfaceEnum topSurface) {
    switch (topSurface) {
    case VoidTopSurfaceEnum::LEX_LOWEST:
      reverseVoidDetection = true;
      detectLargestSurface = false;
      break;
    case VoidTopSurfaceEnum::LEX_HIGHEST:
      reverseVoidDetection = false;
      detectLargestSurface = false;
      break;
    case VoidTopSurfaceEnum::LARGEST:
      reverseVoidDetection = false;
      detectLargestSurface = true;
      break;
    case VoidTopSurfaceEnum::SMALLEST:
      reverseVoidDetection = true;
      detectLargestSurface = true;
      break;
 
    default:
      Logger::getInstance()
          .addWarning("MarkVoidPoints: Invalid VoidTopSurfaceEnum set. "
                      "Using default values.")
          .print();
      reverseVoidDetection = false;
      detectLargestSurface = false;
      break;
    }
  }

  void setSaveComponentIds(bool scid) { saveComponents = scid; }
 
  void apply() {
    lsInternal::Graph graph;
 
    std::vector<std::vector<std::vector<IndexType>>> componentList(
        domain->getNumberOfSegments());
    for (unsigned segmentId = 0; segmentId < domain->getNumberOfSegments();
         ++segmentId) {
      componentList[segmentId].resize(D + 1);
      for (int dim = -1; dim < D; ++dim) {
        componentList[segmentId][dim + 1].resize(
            domain->getDomain().getNumberOfRuns(segmentId, dim), -1);
      }
    }
 
    std::size_t numberOfComponents = 0;
    std::vector<IndexType> pointsPerComponent;
 
    // cycle through and set up the graph to get connectivity information
    for (viennahrle::ConstSparseStarIterator<typename Domain<T, D>::DomainType,
                                             1>
             neighborIt(domain->getDomain());
         !neighborIt.isFinished(); neighborIt.next()) {
      auto &center = neighborIt.getCenter();
 
      // component id of the current run
      auto &currentComponentId =
          componentList[center.getSegmentId()][center.getLevel()]
                       [center.getRunTypePosition()];
 
      // -1 means it is not set yet
      if (currentComponentId == -1) {
        for (int k = 0; k < 2 * D; ++k) {
          auto &neighbor = neighborIt.getNeighbor(k);
          const auto neighborComponentId =
              componentList[neighbor.getSegmentId()][neighbor.getLevel()]
                           [neighbor.getRunTypePosition()];
          // if neighbor is already defined
          // set current component to neighbor component
          // if they are connected
          if (neighborComponentId != -1) {
            if (areConnected(center.getValue(), neighbor.getValue())) {
              currentComponentId = neighborComponentId;
              if (center.getValue() >= 0.)
                ++pointsPerComponent[currentComponentId];
              break;
            }
          }
        }
      }
 
      // it is still not set, so add new vertex
      if (currentComponentId == -1) {
        currentComponentId = numberOfComponents;
        pointsPerComponent.push_back((center.getValue() > 0.) ? 1 : 0);
        graph.insertNextVertex();
        ++numberOfComponents;
      }
 
      // check if edge can be set
      for (int k = 0; k < 2 * D; ++k) {
        auto &neighbor = neighborIt.getNeighbor(k);
        auto &neighborComponentId =
            componentList[neighbor.getSegmentId()][neighbor.getLevel()]
                         [neighbor.getRunTypePosition()];
        if (areConnected(center.getValue(), neighbor.getValue())) {
          // if neighbor is already set
          if (neighborComponentId != -1) {
            // if neighbor is part of different component
            if (currentComponentId != neighborComponentId) {
              graph.insertNextEdge(currentComponentId, neighborComponentId);
            }
          } else {
            neighborComponentId = currentComponentId;
            if (neighbor.getValue() >= 0.)
              ++pointsPerComponent[neighborComponentId];
          }
        }
      }
    }
 
    auto components = graph.getConnectedComponents();
 
    int topComponent =
        (reverseVoidDetection) ? components[0] : components.back();
 
    // identify which layer to keep
    {
      auto pointsPerConnected =
          mergeComponentCounts(components, pointsPerComponent);
 
      // find largest connected surface
      if (detectLargestSurface) {
        topComponent = calculateTopID(components, pointsPerConnected);
      } else { // if component does not contain points, take the next one
        while (pointsPerConnected[topComponent] == 0) {
          if (reverseVoidDetection)
            ++topComponent;
          else
            --topComponent;
        }
      }
    }
 
    std::vector<T> voidPointMarkers;
    voidPointMarkers.resize(domain->getNumberOfPoints());
 
    std::vector<T> componentMarkers;
    if (saveComponents)
      componentMarkers.resize(domain->getNumberOfPoints());
 
    // cycle through again to set correct voidPointMarkers
    for (viennahrle::ConstSparseStarIterator<typename Domain<T, D>::DomainType,
                                             1>
             neighborIt(domain->getDomain());
         !neighborIt.isFinished(); neighborIt.next()) {
      auto center = neighborIt.getCenter();
 
      if (!center.isDefined())
        continue;
 
      // if it is positive, just check if it is part of the top component
      if (center.getValue() >= 0) {
        const int &oldComponentId = componentList[center.getSegmentId()][0]
                                                 [center.getRunTypePosition()];
        voidPointMarkers[center.getPointId()] =
            (components[oldComponentId] != topComponent);
      } else {
        // if it is negative, check all neighbours (with different sign),
        // because they are part of of a positive component, which might
        // be the top
        unsigned k;
        for (k = 0; k < 2 * D; ++k) {
          auto &neighbor = neighborIt.getNeighbor(k);
          if (std::signbit(neighbor.getValue()) ==
              std::signbit(center.getValue()))
            continue;
          const int &oldneighborComponentId =
              componentList[neighbor.getSegmentId()][neighbor.getLevel()]
                           [neighbor.getRunTypePosition()];
          if (components[oldneighborComponentId] == topComponent) {
            break;
          }
        }
        voidPointMarkers[center.getPointId()] = (k == 2 * D);
      }
 
      if (saveComponents) {
        const int &oldComponentId = componentList[center.getSegmentId()][0]
                                                 [center.getRunTypePosition()];
        componentMarkers[center.getPointId()] = components[oldComponentId];
      }
    }
 
    auto &pointData = domain->getPointData();
    auto voidMarkersPointer = pointData.getScalarData(voidPointLabel, true);
    // if vector data does not exist
    if (voidMarkersPointer == nullptr) {
      pointData.insertNextScalarData(voidPointMarkers, voidPointLabel);
    } else {
      *voidMarkersPointer = std::move(voidPointMarkers);
    }
 
    if (saveComponents) {
      auto componentMarkersPointer =
          pointData.getScalarData("ConnectedComponentId", true);
      // if vector data does not exist
      if (componentMarkersPointer == nullptr) {
        pointData.insertNextScalarData(componentMarkers,
                                       "ConnectedComponentId");
      } else {
        *componentMarkersPointer = std::move(componentMarkers);
      }
    }
  }
};
 
} // namespace viennals