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#ifndef PCL_REGISTRATION_DEFAULT_CONVERGENCE_CRITERIA_HPP_
#define PCL_REGISTRATION_DEFAULT_CONVERGENCE_CRITERIA_HPP_

#include <pcl/console/print.h>

namespace pcl {

namespace registration {

template <typename Scalar>
bool
DefaultConvergenceCriteria<Scalar>::hasConverged()
{
  if (convergence_state_ != CONVERGENCE_CRITERIA_NOT_CONVERGED) {
    // If it already converged or failed before, reset.
    iterations_similar_transforms_ = 0;
    convergence_state_ = CONVERGENCE_CRITERIA_NOT_CONVERGED;
  }

  bool is_similar = false;

  PCL_DEBUG("[pcl::DefaultConvergenceCriteria::hasConverged] Iteration %d out of %d.\n",
            iterations_,
            max_iterations_);
  // 1. Number of iterations has reached the maximum user imposed number of iterations
  if (iterations_ >= max_iterations_) {
    if (!failure_after_max_iter_) {
      convergence_state_ = CONVERGENCE_CRITERIA_ITERATIONS;
      return (true);
    }
    convergence_state_ = CONVERGENCE_CRITERIA_FAILURE_AFTER_MAX_ITERATIONS;
  }

  // 2. The epsilon (difference) between the previous transformation and the current
  // estimated transformation
  double cos_angle = 0.5 * (transformation_.coeff(0, 0) + transformation_.coeff(1, 1) +
                            transformation_.coeff(2, 2) - 1);
  double translation_sqr = transformation_.coeff(0, 3) * transformation_.coeff(0, 3) +
                           transformation_.coeff(1, 3) * transformation_.coeff(1, 3) +
                           transformation_.coeff(2, 3) * transformation_.coeff(2, 3);
  PCL_DEBUG("[pcl::DefaultConvergenceCriteria::hasConverged] Current transformation "
            "gave %f rotation (cosine) and %f translation.\n",
            cos_angle,
            translation_sqr);

  if (cos_angle >= rotation_threshold_ && translation_sqr <= translation_threshold_) {
    if (iterations_similar_transforms_ >= max_iterations_similar_transforms_) {
      convergence_state_ = CONVERGENCE_CRITERIA_TRANSFORM;
      return (true);
    }
    is_similar = true;
  }

  correspondences_cur_mse_ = calculateMSE(correspondences_);
  PCL_DEBUG("[pcl::DefaultConvergenceCriteria::hasConverged] Previous / Current MSE "
            "for correspondences distances is: %f / %f.\n",
            correspondences_prev_mse_,
            correspondences_cur_mse_);

  // 3. The relative sum of Euclidean squared errors is smaller than a user defined
  // threshold Absolute
  if (std::abs(correspondences_cur_mse_ - correspondences_prev_mse_) <
      mse_threshold_absolute_) {
    if (iterations_similar_transforms_ >= max_iterations_similar_transforms_) {
      convergence_state_ = CONVERGENCE_CRITERIA_ABS_MSE;
      return (true);
    }
    is_similar = true;
  }

  // Relative
  if (std::abs(correspondences_cur_mse_ - correspondences_prev_mse_) /
          correspondences_prev_mse_ <
      mse_threshold_relative_) {
    if (iterations_similar_transforms_ >= max_iterations_similar_transforms_) {
      convergence_state_ = CONVERGENCE_CRITERIA_REL_MSE;
      return (true);
    }
    is_similar = true;
  }

  if (is_similar) {
    // Increment the number of transforms that the thresholds are allowed to be similar
    ++iterations_similar_transforms_;
  }
  else {
    // When the transform becomes large, reset.
    iterations_similar_transforms_ = 0;
  }

  correspondences_prev_mse_ = correspondences_cur_mse_;

  return (false);
}

} // namespace registration
} // namespace pcl

#endif // PCL_REGISTRATION_DEFAULT_CONVERGENCE_CRITERIA_HPP_