Function getCentroid

src/utilities/geometry/Geometry.cpp:69–113

compute centroid from surface as Point3dVector

/// compute centroid from surface as Point3dVector
OptionalPoint3d getCentroid(const Point3dVector& points) {
  OptionalPoint3d result;

  if (points.size() >= 3) {
    // convert to face coordinates
    const Transformation alignFace = Transformation::alignFace(points);
    Point3dVector surfacePoints = alignFace.inverse() * points;

    const size_t N = surfacePoints.size();
    double A = 0;
    double cx = 0;
    double cy = 0;
    for (size_t i = 0; i < N; ++i) {
      double x1 = 0.0;
      double x2 = 0.0;
      double y1 = 0.0;
      double y2 = 0.0;
      if (i == N - 1) {
        x1 = surfacePoints[i].x();
        x2 = surfacePoints[0].x();
        y1 = surfacePoints[i].y();
        y2 = surfacePoints[0].y();
      } else {
        x1 = surfacePoints[i].x();
        x2 = surfacePoints[i + 1].x();
        y1 = surfacePoints[i].y();
        y2 = surfacePoints[i + 1].y();
      }

      const double dA = (x1 * y2 - x2 * y1);
      A += 0.5 * dA;
      cx += (x1 + x2) * dA;
      cy += (y1 + y2) * dA;
    }

    if (A > 0) {
      // centroid in face coordinates
      const Point3d surfaceCentroid(cx / (6.0 * A), cy / (6.0 * A), 0.0);

      // centroid
      result = alignFace * surfaceCentroid;
    }
  }
  return result;
}

/// reorder points to upper-left-corner convention
Point3dVector reorderULC(const Point3dVector& points) {