Meshborn filter (#2925)

Co-authored-by: Paul Romano <paul.k.romano@gmail.com>

src/particle.cpp

@@ -121,6 +121,7 @@ void Particle::from_source(const SourceSite* src)
   wgt_last() = src->wgt;
   r() = src->r;
   u() = src->u;
+  r_born() = src->r;
   r_last_current() = src->r;
   r_last() = src->r;
   u_last() = src->u;

src/tallies/filter.cpp

@@ -23,6 +23,7 @@
 #include "openmc/tallies/filter_material.h"
 #include "openmc/tallies/filter_materialfrom.h"
 #include "openmc/tallies/filter_mesh.h"
+#include "openmc/tallies/filter_meshborn.h"
 #include "openmc/tallies/filter_meshsurface.h"
 #include "openmc/tallies/filter_mu.h"
 #include "openmc/tallies/filter_particle.h"
@@ -126,6 +127,8 @@ Filter* Filter::create(const std::string& type, int32_t id)
     return Filter::create<MaterialFromFilter>(id);
   } else if (type == "mesh") {
     return Filter::create<MeshFilter>(id);
+  } else if (type == "meshborn") {
+    return Filter::create<MeshBornFilter>(id);
   } else if (type == "meshsurface") {
     return Filter::create<MeshSurfaceFilter>(id);
   } else if (type == "mu") {

src/tallies/filter_mesh.cpp

@@ -161,6 +161,7 @@ extern "C" int openmc_mesh_filter_get_translation(
   // Check the filter type
   const auto& filter = model::tally_filters[index];
   if (filter->type() != FilterType::MESH &&
+      filter->type() != FilterType::MESHBORN &&
       filter->type() != FilterType::MESH_SURFACE) {
     set_errmsg("Tried to get a translation from a non-mesh-based filter.");
     return OPENMC_E_INVALID_TYPE;
@@ -186,6 +187,7 @@ extern "C" int openmc_mesh_filter_set_translation(
   const auto& filter = model::tally_filters[index];
   // Check the filter type
   if (filter->type() != FilterType::MESH &&
+      filter->type() != FilterType::MESHBORN &&
       filter->type() != FilterType::MESH_SURFACE) {
     set_errmsg("Tried to set mesh on a non-mesh-based filter.");
     return OPENMC_E_INVALID_TYPE;

src/tallies/filter_meshborn.cpp

@@ -0,0 +1,61 @@
+#include "openmc/tallies/filter_meshborn.h"
+
+#include "openmc/capi.h"
+#include "openmc/constants.h"
+#include "openmc/error.h"
+#include "openmc/mesh.h"
+
+namespace openmc {
+
+void MeshBornFilter::get_all_bins(
+  const Particle& p, TallyEstimator estimator, FilterMatch& match) const
+{
+  Position r_born = p.r_born();
+
+  // apply translation if present
+  if (translated_) {
+    r_born -= translation();
+  }
+
+  auto bin = model::meshes[mesh_]->get_bin(r_born);
+  if (bin >= 0) {
+    match.bins_.push_back(bin);
+    match.weights_.push_back(1.0);
+  }
+}
+
+std::string MeshBornFilter::text_label(int bin) const
+{
+  auto& mesh = *model::meshes.at(mesh_);
+  return mesh.bin_label(bin) + " (born)";
+}
+
+//==============================================================================
+// C-API functions
+//==============================================================================
+
+extern "C" int openmc_meshborn_filter_get_mesh(
+  int32_t index, int32_t* index_mesh)
+{
+  return openmc_mesh_filter_get_mesh(index, index_mesh);
+}
+
+extern "C" int openmc_meshborn_filter_set_mesh(
+  int32_t index, int32_t index_mesh)
+{
+  return openmc_mesh_filter_set_mesh(index, index_mesh);
+}
+
+extern "C" int openmc_meshborn_filter_get_translation(
+  int32_t index, double translation[3])
+{
+  return openmc_mesh_filter_get_translation(index, translation);
+}
+
+extern "C" int openmc_meshborn_filter_set_translation(
+  int32_t index, double translation[3])
+{
+  return openmc_mesh_filter_set_translation(index, translation);
+}
+
+} // namespace openmc

src/tallies/filter_meshsurface.cpp

@@ -100,4 +100,16 @@ extern "C" int openmc_meshsurface_filter_set_mesh(
   return openmc_mesh_filter_set_mesh(index, index_mesh);
 }
 
+extern "C" int openmc_meshsurface_filter_get_translation(
+  int32_t index, double translation[3])
+{
+  return openmc_mesh_filter_get_translation(index, translation);
+}
+
+extern "C" int openmc_meshsurface_filter_set_translation(
+  int32_t index, double translation[3])
+{
+  return openmc_mesh_filter_set_translation(index, translation);
+}
+
 } // namespace openmc

src/tallies/tally.cpp

@@ -26,6 +26,7 @@
 #include "openmc/tallies/filter_energy.h"
 #include "openmc/tallies/filter_legendre.h"
 #include "openmc/tallies/filter_mesh.h"
+#include "openmc/tallies/filter_meshborn.h"
 #include "openmc/tallies/filter_meshsurface.h"
 #include "openmc/tallies/filter_particle.h"
 #include "openmc/tallies/filter_sph_harm.h"