From 1d07f498612987e6740d1b237db8c2afacc2f990 Mon Sep 17 00:00:00 2001
From: Sterling Harper <smharper@mit.edu>
Date: Sat, 17 Oct 2020 20:59:58 -0600
Subject: [PATCH] Move all BCs to the new BoundaryCondtion class

---
 include/openmc/particle.h  |  3 ++-
 src/boundary_condition.cpp | 31 +++++++++++++++++++++++++++----
 src/particle.cpp           | 29 +++++++----------------------
 src/surface.cpp            |  2 ++
 4 files changed, 38 insertions(+), 27 deletions(-)

diff --git a/include/openmc/particle.h b/include/openmc/particle.h
index 48570c4ea9..f122455fc7 100644
--- a/include/openmc/particle.h
+++ b/include/openmc/particle.h
@@ -247,7 +247,8 @@ public:
   void cross_reflective_bc(const Surface& surf, Direction new_u);
 
   //! Cross a periodic boundary condition.
-  void cross_periodic_bc(const Surface& surf);
+  void cross_periodic_bc(const Surface& surf, Position new_r, Direction new_u,
+                         int new_surface);
 
   //! mark a particle as lost and create a particle restart file
   //! \param message A warning message to display
diff --git a/src/boundary_condition.cpp b/src/boundary_condition.cpp
index d9c463ca09..334f40b311 100644
--- a/src/boundary_condition.cpp
+++ b/src/boundary_condition.cpp
@@ -3,6 +3,12 @@
 
 namespace openmc {
 
+void
+VacuumBC::handle_particle(Particle& p, const Surface& surf) const
+{
+  p.cross_vacuum_bc(surf);
+}
+
 void
 ReflectiveBC::handle_particle(Particle& p, const Surface& surf) const
 {
@@ -21,9 +27,26 @@ WhiteBC::handle_particle(Particle& p, const Surface& surf) const
   p.cross_reflective_bc(surf, u);
 }
 
-//void
-//PeriodicBC::handle_particle(Particle& p, const Surface& surf) const
-//{
-//}
+void
+PeriodicBC::handle_particle(Particle& p, const Surface& surf) const
+{
+  // Get a pointer to the partner periodic surface
+  auto surf_p = dynamic_cast<const PeriodicSurface*>(&surf);
+  auto other = dynamic_cast<const PeriodicSurface*>(
+    model::surfaces[surf_p->i_periodic_].get());
+
+  // Compute the new particle location and direction
+  Position r {p.r()};
+  Direction u {p.u()};
+  bool rotational = other->periodic_translate(surf_p, r, u);
+
+  // Pick the particle's new surface
+  // TODO: off-by-one
+  int new_surface = rotational ?
+    surf_p->i_periodic_ + 1 :
+    ((p.surface_ > 0) ? surf_p->i_periodic_ + 1 : -(surf_p->i_periodic_ + 1));
+
+  p.cross_periodic_bc(surf, r, u, new_surface);
+}
 
 } // namespace openmc
diff --git a/src/particle.cpp b/src/particle.cpp
index ba68ce2eb8..a7532f8c98 100644
--- a/src/particle.cpp
+++ b/src/particle.cpp
@@ -413,23 +413,9 @@ Particle::cross_surface()
     write_message(1, "    Crossing surface {}", surf->id_);
   }
 
-  if (surf->bc_ == Surface::BoundaryType::VACUUM && (settings::run_mode != RunMode::PLOTTING)) {
-
-    cross_vacuum_bc(*surf);
-
-    return;
-
-  } else if ((surf->bc_ == Surface::BoundaryType::REFLECT ||
-              surf->bc_ == Surface::BoundaryType::WHITE)
-              && (settings::run_mode != RunMode::PLOTTING)) {
-
+  // Handle any applicable boundary conditions.
+  if (surf->new_bc_ && settings::run_mode != RunMode::PLOTTING) {
     surf->new_bc_->handle_particle(*this, *surf);
-
-    return;
-
-  } else if (surf->bc_ == Surface::BoundaryType::PERIODIC && settings::run_mode != RunMode::PLOTTING) {
-    cross_periodic_bc(*surf);
-
     return;
   }
 
@@ -570,7 +556,8 @@ Particle::cross_reflective_bc(const Surface& surf, Direction new_u)
 }
 
 void
-Particle::cross_periodic_bc(const Surface& surf)
+Particle::cross_periodic_bc(const Surface& surf, Position new_r,
+                            Direction new_u, int new_surface)
 {
   // Do not handle periodic boundary conditions on lower universes
   if (n_coord_ != 1) {
@@ -596,13 +583,11 @@ Particle::cross_periodic_bc(const Surface& surf)
     model::surfaces[surf_p->i_periodic_].get());
 
   // Adjust the particle's location and direction.
-  bool rotational = other->periodic_translate(surf_p, this->r(), this->u());
+  r() = new_r;
+  u() = new_u;
 
   // Reassign particle's surface
-  // TODO: off-by-one
-  surface_ = rotational ?
-    surf_p->i_periodic_ + 1 :
-    ((surface_ > 0) ? surf_p->i_periodic_ + 1 : -(surf_p->i_periodic_ + 1));
+  surface_ = new_surface;
 
   // Figure out what cell particle is in now
   n_coord_ = 1;
diff --git a/src/surface.cpp b/src/surface.cpp
index 6296e128b4..6957c85235 100644
--- a/src/surface.cpp
+++ b/src/surface.cpp
@@ -130,6 +130,7 @@ Surface::Surface(pugi::xml_node surf_node)
 
     } else if (surf_bc == "vacuum") {
       bc_ = BoundaryType::VACUUM;
+      new_bc_ = std::make_shared<VacuumBC>();
 
     } else if (surf_bc == "reflective" || surf_bc == "reflect"
                || surf_bc == "reflecting") {
@@ -140,6 +141,7 @@ Surface::Surface(pugi::xml_node surf_node)
       new_bc_ = std::make_shared<WhiteBC>();
     } else if (surf_bc == "periodic") {
       bc_ = BoundaryType::PERIODIC;
+      new_bc_ = std::make_shared<PeriodicBC>();
     } else {
       fatal_error(fmt::format("Unknown boundary condition \"{}\" specified "
         "on surface {}", surf_bc, id_));