initial mapping data structure

@@ -1381,2 +1467,2 @@
-                             "internal_dependencies",
-                             N_("Internal Dependencies"),
+                             "id_mappings",
+                             N_("ID Mappings"),

@@ -40,9 +40,21 @@ class DATA_PT_gpencil_modifiers(ModifierButtonsPanel, Panel):
         layout.template_grease_pencil_modifiers()
 
 
+class DATA_UL_nodes_modifier_id_mappings(UIList):

@@ -377,0 +385,4 @@
+  IDProperty *materials_prop = IDP_NewIDPArray(".materials");
+  for (const int i : io_materials->elements().index_range()) {
+    IDPropertyTemplate idprop = {0};
+    IDProperty *material_prop = IDP_New(IDP_GROUP, &idprop, std::to_string(i).c_str());

@@ -377,0 +388,4 @@
+    IDProperty *material_prop = IDP_New(IDP_GROUP, &idprop, std::to_string(i).c_str());
+
+    const DictionaryValue *io_material = io_materials->elements()[i]->as_dictionary_value();
+    if (io_material != nullptr) {

@@ -377,0 +398,4 @@
+    }
+
+    IDP_AppendArray(materials_prop, material_prop);
+    /* IDP_AppendArray does a shallo copy. */

@@ -3719,1 +3723,4 @@
 /** \} */
+
+/* ------------------------------------------------------------------- */
+/** \name Update id mapping in geometry nodes modifier

@@ -3720,0 +3726,4 @@
+/** \name Update id mapping in geometry nodes modifier
+ * \{ */
+
+static ID *find_id_by_names(Main &bmain,

@@ -3720,0 +3727,4 @@
+ * \{ */
+
+static ID *find_id_by_names(Main &bmain,
+                            const blender::StringRef &id_name,

@@ -3720,0 +3775,4 @@
+  nmd.id_mappings = static_cast<NodesModifierIDMapping *>(
+      MEM_reallocN(nmd.id_mappings, sizeof(NodesModifierIDMapping) * new_mappings_num));
+
+  NodesModifierIDMapping *new_mappings = nmd.id_mappings + nmd.id_mappings_num;

@@ -3720,0 +3831,4 @@
+
+  Main *bmain = CTX_data_main(C);
+  Object *ob = ED_object_active_context(C);
+  ModifierData *md = BKE_object_active_modifier(ob);

@@ -3720,0 +3840,4 @@
+  if (nmd.active_id_mapping < 0 || nmd.active_id_mapping >= nmd.id_mappings_num) {
+    return OPERATOR_CANCELLED;
+  }
+  NodesModifierIDMapping &active_mapping = nmd.id_mappings[nmd.active_id_mapping];

@@ -3720,0 +3846,4 @@
+  id_us_min(active_mapping.id);
+  active_mapping.id = nullptr;
+
+  memmove(nmd.id_mappings + nmd.active_id_mapping,

@@ -7057,0 +7095,4 @@
+  RNA_define_lib_overridable(true);
+
+  prop = RNA_def_property(srna, "id_name", PROP_STRING, PROP_NONE);
+  RNA_def_property_ui_text(prop, "ID Name", "Name of the ID that is to be mapped");

@@ -7057,0 +7100,4 @@
+
+  prop = RNA_def_property(srna, "lib_name", PROP_STRING, PROP_NONE);
+  RNA_def_property_ui_text(
+      prop, "Library Name", "Name of the library that contains the ID that is to be mapped");

@@ -355,2 +355,4 @@
       },
       &settings);
+
+  for (const int i : IndexRange(nmd->id_mappings_num)) {

@@ -144,6 +147,35 @@ static void remove_materials(Material ***materials, short *materials_num)
   *materials_num = 0;
 }
 
+static void store_materials_as_id_properties(ID &id)

@@ -179,0 +264,4 @@
+                                           bke::BakeIDMappingIssuesLog *id_mapping_issues)
+{
+  geometry_set.modify_geometry_sets([&](GeometrySet &geometry) {
+    if (Mesh *mesh = geometry.get_mesh_for_write()) {

@@ -176,0 +173,4 @@
+  /**
+   * All simulation states, sorted by frame.
+   */
+  Vector<std::unique_ptr<ModifierSimulationStateAtFrame>> states_at_frames_;

@@ -580,3 +619,2 @@
 
-static std::shared_ptr<io::serialize::ArrayValue> serialize_material_slots(
-    const Span<const Material *> material_slots)
+static void serialize_material_slots(DictionaryValue &io_dict, const IDProperty *id_properties)

@@ -3720,0 +3814,4 @@
+/** \} */
+
+/* ------------------------------------------------------------------- */
+/** \name Remove id mapping in geometry nodes modifier

@@ -3720,0 +3882,4 @@
+/** \} */
+
+/* ------------------------------------------------------------------- */
+/** \name Add id mapping in geometry nodes modifier

@@ -2326,6 +2326,14 @@ typedef struct NodesModifierSettings {
   struct IDProperty *properties;
 } NodesModifierSettings;
 
+typedef struct NodesModifierIDMapping {

@@ -2335,2 +2343,4 @@
    */
   char *simulation_bake_directory;
+
+  int id_mappings_num;

@@ -7057,0 +7108,4 @@
+  RNA_def_property_flag(prop, PROP_EDITABLE | PROP_ID_SELF_CHECK);
+  RNA_def_property_pointer_funcs(
+      prop, nullptr, nullptr, "rna_NodesModifier_id_mapping_id_typef", nullptr);
+  RNA_def_property_ui_text(prop, "ID", "");

@@ -7057,0 +7141,4 @@
+
+  prop = RNA_def_property(srna, "active_index", PROP_INT, PROP_NONE);
+  RNA_def_property_int_sdna(prop, nullptr, "active_id_mapping");
+  RNA_def_property_ui_text(prop, "Active ID Mapping Index", "");

@@ -1405,0 +1483,4 @@
+  RNA_pointer_create(
+      ptr->owner_id, &RNA_NodesModifierIDMapping, &active_mapping, &active_mapping_ptr);
+
+  uiTemplateAnyID(col, &active_mapping_ptr, "id", "id_type", "ID");

@@ -1475,2 +1574,4 @@
     IDP_BlendDataRead(reader, &nmd->settings.properties);
   }
+  BLO_read_data_address(reader, &nmd->id_mappings);
+  for (const NodesModifierIDMapping &mapping : MutableSpan(nmd->id_mappings, nmd->id_mappings_num))

@@ -7057,0 +7113,4 @@
+
+  prop = RNA_def_property(srna, "id_type", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, rna_enum_id_type_items);
+  RNA_def_property_enum_default(prop, ID_MA);

@@ -1405,0 +1488,4 @@
+      ptr->owner_id, &RNA_NodesModifierIDMapping, &active_mapping, &active_mapping_ptr);
+
+  uiTemplateAnyID(col, &active_mapping_ptr, "id", "id_type", "ID");
+  uiItemR(col, &active_mapping_ptr, "id_name", 0, "ID Name", ICON_NONE);