1 files changed, 62 insertions, 5 deletions

diff --git a/source/blender/simulation/intern/simulation_solver.cc b/source/blender/simulation/intern/simulation_solver.cc
index f542d6ab2c8..158c50957df 100644
--- a/source/blender/simulation/intern/simulation_solver.cc
+++ b/source/blender/simulation/intern/simulation_solver.cc
@@ -17,8 +17,11 @@
 #include "simulation_solver.hh"
 
 #include "BKE_customdata.h"
+#include "BKE_lib_id.h"
+#include "BKE_persistent_data_handle.hh"
 
 #include "BLI_rand.hh"
+#include "BLI_set.hh"
 
 namespace blender::sim {
 
@@ -243,6 +246,53 @@ BLI_NOINLINE static void remove_dead_and_add_new_particles(ParticleSimulationSta
   state.next_particle_id += allocator.total_allocated();
 }
 
+static void update_persistent_data_handles(Simulation &simulation,
+                                           const VectorSet<ID *> &used_data_blocks)
+{
+  Set<ID *> contained_ids;
+  Set<int> used_handles;
+
+  /* Remove handles that have been invalidated. */
+  LISTBASE_FOREACH_MUTABLE (
+      PersistentDataHandleItem *, handle_item, &simulation.persistent_data_handles) {
+    if (handle_item->id == nullptr) {
+      BLI_remlink(&simulation.persistent_data_handles, handle_item);
+      continue;
+    }
+    if (!used_data_blocks.contains(handle_item->id)) {
+      id_us_min(handle_item->id);
+      BLI_remlink(&simulation.persistent_data_handles, handle_item);
+      MEM_freeN(handle_item);
+      continue;
+    }
+    contained_ids.add_new(handle_item->id);
+    used_handles.add_new(handle_item->handle);
+  }
+
+  /* Add new handles that are not in the list yet. */
+  int next_handle = 0;
+  for (ID *id : used_data_blocks) {
+    if (contained_ids.contains(id)) {
+      continue;
+    }
+
+    /* Find the next available handle. */
+    while (used_handles.contains(next_handle)) {
+      next_handle++;
+    }
+    used_handles.add_new(next_handle);
+
+    PersistentDataHandleItem *handle_item = (PersistentDataHandleItem *)MEM_callocN(
+        sizeof(*handle_item), AT);
+    /* Cannot store const pointers in DNA. */
+    id_us_plus(id);
+    handle_item->id = id;
+    handle_item->handle = next_handle;
+
+    BLI_addtail(&simulation.persistent_data_handles, handle_item);
+  }
+}
+
 void initialize_simulation_states(Simulation &simulation,
                                   Depsgraph &UNUSED(depsgraph),
                                   const SimulationInfluences &UNUSED(influences))
@@ -255,11 +305,18 @@ void solve_simulation_time_step(Simulation &simulation,
                                 const SimulationInfluences &influences,
                                 float time_step)
 {
-  SimulationSolveContext solve_context{
-      simulation,
-      depsgraph,
-      influences,
-      TimeInterval(simulation.current_simulation_time, time_step)};
+  update_persistent_data_handles(simulation, influences.used_data_blocks);
+
+  bke::PersistentDataHandleMap handle_map;
+  LISTBASE_FOREACH (PersistentDataHandleItem *, handle, &simulation.persistent_data_handles) {
+    handle_map.add(handle->handle, *handle->id);
+  }
+
+  SimulationSolveContext solve_context{simulation,
+                                       depsgraph,
+                                       influences,
+                                       TimeInterval(simulation.current_simulation_time, time_step),
+                                       handle_map};
   TimeInterval simulation_time_interval{simulation.current_simulation_time, time_step};
 
   Vector<SimulationState *> simulation_states{simulation.states};