node.h

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// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) 2026, Liam Pohlmann
 
#ifndef HUMMINGBIRD_MESH_NODE_H_
#define HUMMINGBIRD_MESH_NODE_H_
 
#include <armadillo>
#include <cmath>
#include <cstddef>
#include <cstdint>
#include <vector>
 
#include "banks/material_bank.h"
#include "quadrature/angular/ordinate.h"
#include "quadrature/quadrature_base.h"
#include "utils/enums.h"
 
namespace hummingbird {
class SourceBank;
 
/**
 * @brief A point in the mesh holding its coordinates, boundary info, and flux
 * solution values
 *
 */
struct Node {
  /// @brief Unique identifier for the node
  size_t id;
 
  /// @brief X-coordinate of the node
  double x;
 
  /// @brief Y-coordinate of the node
  double y;
 
  /// @brief Z-coordinate of the node
  double z;
 
  /// @brief BC ID to access the boundary condition (BC) bank. ID of 0 is always
  /// NONE, meaning the node is internal to the mesh.
  int bc_id = 0;
 
  /// @brief Outward pointing normal vector. This vector is only relevant if the
  /// node is on a boundary
  arma::vec3 outward_normal;
 
  /// @brief Scalar flux on the node
  double scalar_flux;
 
  /// @brief Angular flux values in order of the SN quadrature set
  std::vector<double> angular_fluxes;
 
  /// @brief Source flux values in order of the SN quadrature set. These are
  /// scratch values: they are overwritten for each element during forcing
  /// assembly (see Element::SetNodeSourceFluxes), so on interface nodes they
  /// hold the last element's values. Do not read them outside assembly.
  std::vector<double> source_fluxes;
};
 
/**
 * @brief Compute the Euclidean distance between two nodes
 *
 * @param node_1 First node
 * @param node_2 Second node
 * @return Distance in units of the mesh
 */
double DistanceBetweenNodes(const Node& node_1, const Node& node_2);
 
/**
 * @brief Update the scalar flux of a node using the angular quadrature set
 *
 * @param node Node to update
 * @param angular_quadrature Angular quadrature set
 */
void UpdateScalarFlux(Node& node,
                      const QuadratureBase<Ordinate> angular_quadrature);
 
/**
 * @brief Compute the node source flux values
 *
 * @param node Node
 * @param material_id Material ID
 * @param source_id Source ID
 * @param material_bank Material bank
 * @param source_bank Source bank
 * @param angular_quadrature Angular quadrature set
 * @return std::vector<double>
 */
std::vector<double> ComputeNodeSourceFluxes(
    const Node& node, const int material_id, const int source_id,
    const MaterialBank& material_bank, const SourceBank& source_bank,
    const QuadratureBase<Ordinate>& angular_quadrature);
}  // namespace hummingbird
 
#endif  // HUMMINGBIRD_MESH_NODE_H_