scripts/startup/bl_operators/geometry_nodes.py

@@ -5,6 +5,10 @@ from bpy.types import Operator
 
 from bpy.app.translations import pgettext_data as data_
 
+from bpy.props import (
+    EnumProperty,
+)
+
 
 def build_default_empty_geometry_node_group(name):
     group = bpy.data.node_groups.new(name, 'GeometryNodeTree')
@@ -237,8 +241,102 @@ class NewGeometryNodeTreeAssign(Operator):
         return {'FINISHED'}
 
 
+class SimulationZoneOperator():
+    input_node_type = 'GeometryNodeSimulationInput'
+    output_node_type = 'GeometryNodeSimulationOutput'
+
+    @classmethod
+    def get_output_node(cls, context):
+        node = context.active_node
+        if node.bl_idname == cls.input_node_type:
+            return node.paired_output
+        if node.bl_idname == cls.output_node_type:
+            return node
+
+    @classmethod
+    def poll(cls, context):
+        space = context.space_data
+        # Needs active node editor and a tree.
+        if not space or space.type != 'NODE_EDITOR' or not space.edit_tree or space.edit_tree.library:
+            return False
+        node = context.active_node
+        if node is None or node.bl_idname not in [cls.input_node_type, cls.output_node_type]:
+            return False
+        if cls.get_output_node(context) is None:
+            return False
+        return True
+
+
+class SimulationZoneItemAddOperator(SimulationZoneOperator, Operator):
+    '''Add a state item to the simulation zone'''
+    bl_idname = "node.simulation_zone_item_add"
+    bl_label = "Add State Item"
+    bl_options = {'REGISTER', 'UNDO'}
+
+    default_socket_type = 'GEOMETRY'
+
+    def execute(self, context):
+        node = self.get_output_node(context)
+        state_items = node.state_items
+
+        # Remember index to move the item.
+        dst_index = min(node.active_index + 1, len(state_items))
+        # Empty name so it is based on the type only.
+        state_items.new(self.default_socket_type, "")
+        state_items.move(len(state_items) - 1, dst_index)
+        node.active_index = dst_index
+
+        return {'FINISHED'}
+
+
+class SimulationZoneItemRemoveOperator(SimulationZoneOperator, Operator):
+    '''Remove a state item from the simulation zone'''
+    bl_idname = "node.simulation_zone_item_remove"
+    bl_label = "Remove State Item"
+    bl_options = {'REGISTER', 'UNDO'}
+
+    def execute(self, context):
+        node = self.get_output_node(context)
+        state_items = node.state_items
+
+        if node.active_item:
+            state_items.remove(node.active_item)
+            node.active_index = min(node.active_index, len(state_items) - 1)
+
+        return {'FINISHED'}
+
+
+class SimulationZoneItemMoveOperator(SimulationZoneOperator, Operator):
+    '''Move a simulation state item up or down in the list'''
+    bl_idname = "node.simulation_zone_item_move"
+    bl_label = "Move State Item"
+    bl_options = {'REGISTER', 'UNDO'}
+
+    direction: EnumProperty(
+        name="Direction",
+        items=[('UP', "Up", ""), ('DOWN', "Down", "")],
+        default = 'UP',
+    )
+
+    def execute(self, context):
+        node = self.get_output_node(context)
+        state_items = node.state_items
+
+        if self.direction == 'UP' and node.active_index > 0:
+            state_items.move(node.active_index, node.active_index - 1)
+            node.active_index = node.active_index - 1
+        elif self.direction == 'DOWN' and node.active_index < len(state_items) - 1:
+            state_items.move(node.active_index, node.active_index + 1)
+            node.active_index = node.active_index + 1
+
+        return {'FINISHED'}
+
+
 classes = (
     NewGeometryNodesModifier,
     NewGeometryNodeTreeAssign,
     MoveModifierToNodes,
+    SimulationZoneItemAddOperator,
+    SimulationZoneItemRemoveOperator,
+    SimulationZoneItemMoveOperator,
 )

scripts/startup/bl_ui/space_node.py

@@ -954,6 +954,76 @@ class NODE_PT_node_tree_interface_outputs(NodeTreeInterfacePanel):
         self.draw_socket_list(context, "OUT", "outputs", "active_output")
 
 
+class NODE_UL_simulation_zone_items(bpy.types.UIList):
+    def draw_item(self, context, layout, _data, item, icon, _active_data, _active_propname, _index):
+        if self.layout_type in {'DEFAULT', 'COMPACT'}:
+            row = layout.row(align=True)
+
+            row.template_node_socket(color=item.color)
+            row.prop(item, "name", text="", emboss=False, icon_value=icon)
+        elif self.layout_type == 'GRID':
+            layout.alignment = 'CENTER'
+            layout.template_node_socket(color=item.color)
+
+
+class NODE_PT_simulation_zone_items(Panel):
+    bl_space_type = 'NODE_EDITOR'
+    bl_region_type = 'UI'
+    bl_category = "Node"
+    bl_label = "Simulation State"
+
+    input_node_type = 'GeometryNodeSimulationInput'
+    output_node_type = 'GeometryNodeSimulationOutput'
+
+    @classmethod
+    def get_output_node(cls, context):
+        node = context.active_node
+        if node.bl_idname == cls.input_node_type:
+            return node.paired_output
+        if node.bl_idname == cls.output_node_type:
+            return node
+
+    @classmethod
+    def poll(cls, context):
+        snode = context.space_data
+        if snode is None:
+            return False
+        node = context.active_node
+        if node is None or node.bl_idname not in [cls.input_node_type, cls.output_node_type]:
+            return False
+        if cls.get_output_node(context) is None:
+            return False
+        return True
+
+    def draw(self, context):
+        layout = self.layout
+
+        output_node = self.get_output_node(context)
+
+        split = layout.row()
+
+        split.template_list("NODE_UL_simulation_zone_items", "", output_node, "state_items", output_node, "active_index")
+
+        ops_col = split.column()
+
+        add_remove_col = ops_col.column(align=True)
+        add_remove_col.operator("node.simulation_zone_item_add", icon='ADD', text="")
+        add_remove_col.operator("node.simulation_zone_item_remove", icon='REMOVE', text="")
+
+        ops_col.separator()
+
+        up_down_col = ops_col.column(align=True)
+        props = up_down_col.operator("node.simulation_zone_item_move", icon='TRIA_UP', text="")
+        props.direction = 'UP'
+        props = up_down_col.operator("node.simulation_zone_item_move", icon='TRIA_DOWN', text="")
+        props.direction = 'DOWN'
+
+        active_item = output_node.active_item
+        if active_item is not None:
+            layout.prop(active_item, "socket_type")
+            layout.prop(active_item, "name")
+
+
 # Grease Pencil properties
 class NODE_PT_annotation(AnnotationDataPanel, Panel):
     bl_space_type = 'NODE_EDITOR'
@@ -1018,6 +1088,8 @@ classes = (
     NODE_UL_interface_sockets,
     NODE_PT_node_tree_interface_inputs,
     NODE_PT_node_tree_interface_outputs,
+    NODE_UL_simulation_zone_items,
+    NODE_PT_simulation_zone_items,
 
     node_panel(EEVEE_MATERIAL_PT_settings),
     node_panel(MATERIAL_PT_viewport),

source/blender/blenkernel/intern/node_tree_update.cc

@@ -572,6 +572,15 @@ class NodeTreeMainUpdater {
         return true;
       }
     }
+    /* Check paired simulation zone nodes. */
+    if (node.type == GEO_NODE_SIMULATION_INPUT) {
+      const NodeGeometrySimulationInput *data = static_cast<const NodeGeometrySimulationInput *>(node.storage);
+      if (const bNode *output_node = ntree.node_by_id(data->output_node_id)) {
+        if (output_node->runtime->changed_flag & NTREE_CHANGED_NODE_PROPERTY) {
+          return true;
+        }
+      }
+    }
     return false;
   }
 

source/blender/blenloader/intern/versioning_300.cc

@@ -4308,6 +4308,70 @@ void blo_do_versions_300(FileData *fd, Library * /*lib*/, Main *bmain)
 
     /* Rename Grease Pencil weight draw brush. */
     do_versions_rename_id(bmain, ID_BR, "Draw Weight", "Weight Draw");
+
+    /* Identifier generation for simulation node sockets changed.
+     * Update identifiers so links are not removed during validation. */
+    if (!DNA_struct_elem_find(fd->filesdna, "NodeSimulationItem", "int", "identifier")) {
+      static auto set_socket_identifiers = [](bNode *node, const bNode *output_node, int extra_outputs) {
+        const NodeGeometrySimulationOutput *output_data = static_cast<const NodeGeometrySimulationOutput *>(output_node->storage);
+        /* Includes extension socket. */
+        BLI_assert(BLI_listbase_count(&node->inputs) == output_data->items_num + 1);
+        /* Includes extension socket. */
+        BLI_assert(BLI_listbase_count(&node->outputs) == output_data->items_num + 1 + extra_outputs);
+
+        int i;
+        LISTBASE_FOREACH_INDEX (bNodeSocket *, sock, &node->inputs, i) {
+          /* Skip extension socket. */
+          if (i >= output_data->items_num) {
+            break;
+          }
+          BLI_snprintf(sock->identifier, sizeof(sock->identifier), "Item_%d", output_data->items[i].identifier);
+        }
+        LISTBASE_FOREACH_INDEX (bNodeSocket *, sock, &node->outputs, i) {
+          const int item_i = i - extra_outputs;
+          /* Skip extra outputs. */
+          if (i < extra_outputs) {
+            continue;
+          }
+          /* Skip extension socket. */
+          if (item_i >= output_data->items_num) {
+            break;
+          }
+          BLI_snprintf(sock->identifier, sizeof(sock->identifier), "Item_%d", output_data->items[i - extra_outputs].identifier);
+        }
+      };
+
+      LISTBASE_FOREACH (bNodeTree *, ntree, &bmain->nodetrees) {
+        if (ntree->type == NTREE_GEOMETRY) {
+          /* Initialize item identifiers. */
+          LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
+            if (node->type == GEO_NODE_SIMULATION_OUTPUT) {
+              NodeGeometrySimulationOutput *data = static_cast<NodeGeometrySimulationOutput *>(node->storage);
+              for (int i = 0; i < data->items_num; ++i) {
+                data->items[i].identifier = i;
+              }
+              data->next_identifier = data->items_num;
+            }
+          }
+
+          LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
+            if (node->type == GEO_NODE_SIMULATION_INPUT) {
+              const NodeGeometrySimulationInput *input_data = static_cast<const NodeGeometrySimulationInput *>(node->storage);
+              LISTBASE_FOREACH (bNode *, output_node, &ntree->nodes) {
+                if (output_node->identifier == input_data->output_node_id) {
+                  /* 'Delta Time' socket in input nodes */
+                  set_socket_identifiers(node, output_node, 1);
+                  break;
+                }
+              }
+            }
+            if (node->type == GEO_NODE_SIMULATION_OUTPUT) {
+              set_socket_identifiers(node, node, 0);
+            }
+          }
+        }
+      }
+    }
   }
 
   /**

source/blender/editors/include/ED_node.h

@@ -73,6 +73,7 @@ void ED_init_node_socket_type_virtual(struct bNodeSocketType *stype);
 void ED_node_sample_set(const float col[4]);
 void ED_node_draw_snap(
     struct View2D *v2d, const float cent[2], float size, NodeBorder border, unsigned int pos);
+void ED_node_type_draw_color(const char *idname, float *r_color);
 
 /* node_draw.cc */
 

source/blender/editors/space_node/drawnode.cc

@@ -1497,6 +1497,23 @@ void ED_init_node_socket_type_virtual(bNodeSocketType *stype)
   stype->draw_color = node_socket_virtual_draw_color;
 }
 
+void ED_node_type_draw_color(const char *idname, float *r_color)
+{
+  using namespace blender::ed::space_node;
+
+  const bNodeSocketType *typeinfo = nodeSocketTypeFind(idname);
+  if (!typeinfo || typeinfo->type == SOCK_CUSTOM) {
+    r_color[0] = 0.0f;
+    r_color[1] = 0.0f;
+    r_color[2] = 0.0f;
+    r_color[3] = 0.0f;
+    return;
+  }
+
+  BLI_assert(typeinfo->type < ARRAY_SIZE(std_node_socket_colors));
+  copy_v4_v4(r_color, std_node_socket_colors[typeinfo->type]);
+}
+
 namespace blender::ed::space_node {
 
 /* ************** Generic drawing ************** */

source/blender/makesdna/DNA_node_types.h

@@ -16,6 +16,8 @@
 #ifdef __cplusplus
 namespace blender {
 template<typename T> class Span;
+template<typename T> class MutableSpan;
+class IndexRange;
 class StringRef;
 class StringRefNull;
 }  // namespace blender
@@ -1600,7 +1602,9 @@ typedef struct NodeSimulationItem {
   /* #eNodeSocketDatatype. */
   /* TODO: Use a different enum instead to support Byte colors, etc. */
   short socket_type;
-  char _pad[6];
+  short _pad;
+  /* Generates unique identifier for sockets. */
+  int identifier;
 } NodeSimulationItem;
 
 typedef struct NodeGeometrySimulationInput {
@@ -1610,7 +1614,16 @@ typedef struct NodeGeometrySimulationInput {
 typedef struct NodeGeometrySimulationOutput {
   NodeSimulationItem *items;
   int items_num;
-  char _pad[4];
+  int active_index;
+  /* Number to give unique IDs to state items. */
+  int next_identifier;
+  int _pad;
+
+#ifdef __cplusplus
+  blender::Span<NodeSimulationItem> items_span() const;
+  blender::MutableSpan<NodeSimulationItem> items_span_for_write();
+  blender::IndexRange items_range() const;
+#endif
 } NodeGeometrySimulationOutput;
 
 typedef struct NodeGeometryDistributePointsInVolume {

source/blender/makesrna/intern/rna_nodetree.c

@@ -52,6 +52,8 @@
 #include "RE_texture.h"
 
 #include "NOD_composite.h"
+#include "NOD_geometry.h"
+#include "NOD_socket.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
@@ -4087,6 +4089,60 @@ static void rna_NodeCryptomatte_update_remove(Main *bmain, Scene *scene, Pointer
   rna_Node_update(bmain, scene, ptr);
 }
 
+static void rna_SimulationStateItem_update(Main *bmain, Scene *UNUSED(scene), PointerRNA *ptr)
+{
+  bNodeTree *ntree = (bNodeTree *)ptr->owner_id;
+  NodeSimulationItem *item = (NodeSimulationItem *)ptr->data;
+  bNode *node = NOD_geometry_simulation_output_find_node_by_item(ntree, item);
+
+  BKE_ntree_update_tag_node_property(ntree, node);
+  ED_node_tree_propagate_change(NULL, bmain, ntree);
+}
+
+static bool rna_SimulationStateItem_socket_type_supported(const EnumPropertyItem *item)
+{
+  return NOD_geometry_simulation_output_item_socket_type_supported((eNodeSocketDatatype)item->value);
+}
+
+static const EnumPropertyItem *rna_SimulationStateItem_socket_type_itemf(bContext *UNUSED(C),
+                                                                         PointerRNA *UNUSED(ptr),
+                                                                         PropertyRNA *UNUSED(prop),
+                                                                         bool *r_free)
+{
+  *r_free = true;
+  return itemf_function_check(node_socket_data_type_items, rna_SimulationStateItem_socket_type_supported);
+}
+
+static void rna_SimulationStateItem_name_set(PointerRNA *ptr, const char *value)
+{
+  bNodeTree *ntree = (bNodeTree *)ptr->owner_id;
+  NodeSimulationItem *item = (NodeSimulationItem *)ptr->data;
+  bNode *node = NOD_geometry_simulation_output_find_node_by_item(ntree, item);
+  NodeGeometrySimulationOutput *sim = (NodeGeometrySimulationOutput *)node->storage;
+
+  const char *defname = nodeStaticSocketLabel(item->socket_type, 0);
+  NOD_geometry_simulation_output_item_set_unique_name(sim, item, value, defname);
+}
+
+static void rna_SimulationStateItem_color_get(PointerRNA *ptr, float *values)
+{
+  bNodeTree *ntree = (bNodeTree *)ptr->owner_id;
+  NodeSimulationItem *item = (NodeSimulationItem *)ptr->data;
+
+  const char *socket_type_idname = nodeStaticSocketType(item->socket_type, 0);
+  node_type_draw_color(socket_type_idname, values);
+}
+
+static PointerRNA rna_NodeGeometrySimulationInput_paired_output_get(PointerRNA *ptr)
+{
+  bNodeTree *ntree = (bNodeTree *)ptr->owner_id;
+  bNode *node = (bNode *)ptr->data;
+  bNode *output_node = NOD_geometry_simulation_input_get_paired_output(ntree, node);
+  PointerRNA r_ptr;
+  RNA_pointer_create(&ntree->id, &RNA_Node, output_node, &r_ptr);
+  return r_ptr;
+}
+
 static bool rna_GeometryNodeSimulationInput_pair_with_output(
     ID *id, bNode *node, bContext *C, ReportList *reports, bNode *output_node)
 {
@@ -4108,6 +4164,100 @@ static bool rna_GeometryNodeSimulationInput_pair_with_output(
   return true;
 }
 
+static NodeSimulationItem *rna_NodeGeometrySimulationOutput_items_new(
+    ID *id,
+    bNode *node,
+    Main *bmain,
+    ReportList *reports,
+    int socket_type,
+    const char *name)
+{
+  NodeGeometrySimulationOutput *sim = (NodeGeometrySimulationOutput *)node->storage;
+  NodeSimulationItem *item = NOD_geometry_simulation_output_add_item(sim, (short)socket_type, name);
+
+  if (item == NULL) {
+    BKE_report(reports, RPT_ERROR, "Unable to create socket");
+  }
+  else {
+    bNodeTree *ntree = (bNodeTree *)id;
+    BKE_ntree_update_tag_node_property(ntree, node);
+    ED_node_tree_propagate_change(NULL, bmain, ntree);
+    WM_main_add_notifier(NC_NODE | NA_EDITED, ntree);
+  }
+
+  return item;
+}
+
+static void rna_NodeGeometrySimulationOutput_items_remove(ID *id,
+                                                          bNode *node,
+                                                          Main *bmain,
+                                                          ReportList *reports,
+                                                          NodeSimulationItem *item)
+{
+  NodeGeometrySimulationOutput *sim = (NodeGeometrySimulationOutput *)node->storage;
+  if (!NOD_geometry_simulation_output_contains_item(sim, item)) {
+    BKE_reportf(reports, RPT_ERROR, "Unable to locate item '%s' in node", item->name);
+  }
+  else {
+    NOD_geometry_simulation_output_remove_item(sim, item);
+
+    bNodeTree *ntree = (bNodeTree *)id;
+    BKE_ntree_update_tag_node_property(ntree, node);
+    ED_node_tree_propagate_change(NULL, bmain, ntree);
+    WM_main_add_notifier(NC_NODE | NA_EDITED, ntree);
+  }
+}
+
+static void rna_NodeGeometrySimulationOutput_items_clear(ID *id,
+                                                         bNode *node,
+                                                         Main *bmain)
+{
+  NodeGeometrySimulationOutput *sim = (NodeGeometrySimulationOutput *)node->storage;
+  NOD_geometry_simulation_output_clear_items(sim);
+
+  bNodeTree *ntree = (bNodeTree *)id;
+  BKE_ntree_update_tag_node_property(ntree, node);
+  ED_node_tree_propagate_change(NULL, bmain, ntree);
+  WM_main_add_notifier(NC_NODE | NA_EDITED, ntree);
+}
+
+static void rna_NodeGeometrySimulationOutput_items_move(ID *id,
+                                                        bNode *node,
+                                                        Main *bmain,
+                                                        int from_index,
+                                                        int to_index)
+{
+  NodeGeometrySimulationOutput *sim = (NodeGeometrySimulationOutput *)node->storage;
+
+  if (from_index < 0 || from_index >= sim->items_num || to_index < 0 || to_index >= sim->items_num) {
+    return;
+  }
+
+  NOD_geometry_simulation_output_move_item(sim, from_index, to_index);
+
+  bNodeTree *ntree = (bNodeTree *)id;
+  BKE_ntree_update_tag_node_property(ntree, node);
+  ED_node_tree_propagate_change(NULL, bmain, ntree);
+  WM_main_add_notifier(NC_NODE | NA_EDITED, ntree);
+}
+
+static PointerRNA rna_NodeGeometrySimulationOutput_active_item_get(PointerRNA *ptr)
+{
+  bNode *node = (bNode *)ptr->data;
+  NodeGeometrySimulationOutput *sim = (NodeGeometrySimulationOutput *)node->storage;
+  NodeSimulationItem *item = NOD_geometry_simulation_output_get_active_item(sim);
+  PointerRNA r_ptr;
+  RNA_pointer_create(ptr->owner_id, &RNA_SimulationStateItem, item, &r_ptr);
+  return r_ptr;
+}
+
+static void rna_NodeGeometrySimulationOutput_active_item_set(PointerRNA *ptr, PointerRNA value)
+{
+  bNode *node = (bNode *)ptr->data;
+  NodeGeometrySimulationOutput *sim = (NodeGeometrySimulationOutput *)node->storage;
+  NOD_geometry_simulation_output_set_active_item(sim, (NodeSimulationItem *)value.data);
+}
+
 /* ******** Node Socket Types ******** */
 
 static PointerRNA rna_NodeOutputFile_slot_layer_get(CollectionPropertyIterator *iter)
@@ -9759,9 +9909,19 @@ static void def_geo_set_curve_normal(StructRNA *srna)
 
 static void def_geo_simulation_input(StructRNA *srna)
 {
+  PropertyRNA *prop;
   FunctionRNA *func;
   PropertyRNA *parm;
 
+  RNA_def_struct_sdna_from(srna, "NodeGeometrySimulationInput", "storage");
+
+  prop = RNA_def_property(srna, "paired_output", PROP_POINTER, PROP_NONE);
+  RNA_def_property_struct_type(prop, "Node");
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+  RNA_def_property_pointer_funcs(
+      prop, "rna_NodeGeometrySimulationInput_paired_output_get", NULL, NULL, NULL);
+  RNA_def_property_ui_text(prop, "Paired Output", "Simulation output node that this input node is paired with");
+
   func = RNA_def_function(
       srna, "pair_with_output", "rna_GeometryNodeSimulationInput_pair_with_output");
   RNA_def_function_ui_description(func, "Pair a simulation input node with an output node.");
@@ -9777,16 +9937,71 @@ static void def_geo_simulation_input(StructRNA *srna)
 
 static void rna_def_simulation_state_item(BlenderRNA *brna)
 {
-  StructRNA *srna = RNA_def_struct(brna, "SimulationStateItem", NULL);
-  RNA_def_struct_ui_text(srna, "Simulation Sate Item", "");
-  RNA_def_struct_sdna(srna, "NodeSimulationItem");
-
   PropertyRNA *prop;
 
+  StructRNA *srna = RNA_def_struct(brna, "SimulationStateItem", NULL);
+  RNA_def_struct_ui_text(srna, "Simulation Item", "");
+  RNA_def_struct_sdna(srna, "NodeSimulationItem");
+
   prop = RNA_def_property(srna, "name", PROP_STRING, PROP_NONE);
+  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_SimulationStateItem_name_set");
   RNA_def_property_ui_text(prop, "Name", "");
   RNA_def_struct_name_property(srna, prop);
-  RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_NodeSocket_update");
+  RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_SimulationStateItem_update");
+
+  prop = RNA_def_property(srna, "socket_type", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, node_socket_data_type_items);
+  RNA_def_property_enum_funcs(prop, NULL, NULL, "rna_SimulationStateItem_socket_type_itemf");
+  RNA_def_property_ui_text(prop, "Socket Type", "");
+  RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_SimulationStateItem_update");
+
+  prop = RNA_def_property(srna, "color", PROP_FLOAT, PROP_COLOR_GAMMA);
+  RNA_def_property_array(prop, 4);
+  RNA_def_property_float_funcs(prop, "rna_SimulationStateItem_color_get", NULL, NULL);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+  RNA_def_property_ui_text(prop, "Color", "Socket color");
+}
+
+static void rna_def_geo_simulation_output_items(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *parm;
+  FunctionRNA *func;
+
+  srna = RNA_def_struct(brna, "NodeGeometrySimulationOutputItems", NULL);
+  RNA_def_struct_sdna(srna, "bNode");
+  RNA_def_struct_ui_text(srna, "Items", "Collection of simulation items");
+
+  func = RNA_def_function(srna, "new", "rna_NodeGeometrySimulationOutput_items_new");
+  RNA_def_function_ui_description(func, "Add a item to this simulation zone");
+  RNA_def_function_flag(func, FUNC_USE_SELF_ID | FUNC_USE_MAIN | FUNC_USE_REPORTS);
+  parm = RNA_def_enum(func, "socket_type", node_socket_data_type_items, SOCK_GEOMETRY, "Socket Type", "Socket type of the item");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  parm = RNA_def_string(func, "name", NULL, MAX_NAME, "Name", "");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  /* return value */
+  parm = RNA_def_pointer(func, "item", "SimulationStateItem", "Item", "New item");
+  RNA_def_function_return(func, parm);
+
+  func = RNA_def_function(srna, "remove", "rna_NodeGeometrySimulationOutput_items_remove");
+  RNA_def_function_ui_description(func, "Remove an item from this simulation zone");
+  RNA_def_function_flag(func, FUNC_USE_SELF_ID | FUNC_USE_MAIN | FUNC_USE_REPORTS);
+  parm = RNA_def_pointer(func, "item", "SimulationStateItem", "Item", "The item to remove");
+  RNA_def_parameter_flags(parm, PROP_NEVER_NULL, PARM_REQUIRED);
+
+  func = RNA_def_function(srna, "clear", "rna_NodeGeometrySimulationOutput_items_clear");
+  RNA_def_function_ui_description(func, "Remove all items from this simulation zone");
+  RNA_def_function_flag(func, FUNC_USE_SELF_ID | FUNC_USE_MAIN);
+
+  func = RNA_def_function(srna, "move", "rna_NodeGeometrySimulationOutput_items_move");
+  RNA_def_function_ui_description(func, "Move an item to another position");
+  RNA_def_function_flag(func, FUNC_USE_SELF_ID | FUNC_USE_MAIN);
+  parm = RNA_def_int(
+      func, "from_index", -1, 0, INT_MAX, "From Index", "Index of the item to move", 0, 10000);
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  parm = RNA_def_int(
+      func, "to_index", -1, 0, INT_MAX, "To Index", "Target index for the item", 0, 10000);
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
 }
 
 static void def_geo_simulation_output(StructRNA *srna)
@@ -9798,7 +10013,24 @@ static void def_geo_simulation_output(StructRNA *srna)
   prop = RNA_def_property(srna, "state_items", PROP_COLLECTION, PROP_NONE);
   RNA_def_property_collection_sdna(prop, NULL, "items", "items_num");
   RNA_def_property_struct_type(prop, "SimulationStateItem");
-  RNA_def_property_ui_text(prop, "Inputs", "");
+  RNA_def_property_ui_text(prop, "Items", "");
+  RNA_def_property_srna(prop, "NodeGeometrySimulationOutputItems");
+
+  prop = RNA_def_property(srna, "active_index", PROP_INT, PROP_UNSIGNED);
+  RNA_def_property_int_sdna(prop, NULL, "active_index");
+  RNA_def_property_ui_text(prop, "Active Item Index", "Index of the active item");
+  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_update(prop, NC_NODE, NULL);
+
+  prop = RNA_def_property(srna, "active_item", PROP_POINTER, PROP_NONE);
+  RNA_def_property_struct_type(prop, "SimulationStateItem");
+  RNA_def_property_pointer_funcs(prop,
+                                 "rna_NodeGeometrySimulationOutput_active_item_get",
+                                 "rna_NodeGeometrySimulationOutput_active_item_set",
+                                 NULL,
+                                 NULL);
+  RNA_def_property_ui_text(prop, "Active Item Index", "Index of the active item");
+  RNA_def_property_update(prop, NC_NODE, NULL);
 }
 
 static void def_geo_curve_handle_type_selection(StructRNA *srna)
@@ -13222,6 +13454,7 @@ void RNA_def_nodetree(BlenderRNA *brna)
   /* special socket types */
   rna_def_cmp_output_file_slot_file(brna);
   rna_def_cmp_output_file_slot_layer(brna);
+  rna_def_geo_simulation_output_items(brna);
 
   rna_def_node_instance_hash(brna);
 }

source/blender/nodes/NOD_geometry.h

@@ -13,16 +13,70 @@ extern struct bNodeTreeType *ntreeType_Geometry;
 void register_node_type_geo_custom_group(bNodeType *ntype);
 
 /* -------------------------------------------------------------------- */
-/** \name Simulation Node API
+/** \name Simulation Input Node
  * \{ */
 
+struct bNode *NOD_geometry_simulation_input_get_paired_output(
+    struct bNodeTree *node_tree, const struct bNode *simulation_input_node);
+
 /**
  * Pair a simulation input node with an output node.
  * \return True if pairing the node was successful.
  */
 bool NOD_geometry_simulation_input_pair_with_output(const struct bNodeTree *node_tree,
-                                                    struct bNode *sim_input_node,
-                                                    const struct bNode *sim_output_node);
+                                                    struct bNode *simulation_input_node,
+                                                    const struct bNode *simulation_output_node);
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Simulation Output Node
+ * \{ */
+
+bool NOD_geometry_simulation_output_item_socket_type_supported(eNodeSocketDatatype socket_type);
+
+/**
+ * Set a unique item name.
+ * \return True if the unique name differs from the original name.
+ */
+bool NOD_geometry_simulation_output_item_set_unique_name(struct NodeGeometrySimulationOutput *sim,
+                                                         struct NodeSimulationItem *item,
+                                                         const char *name,
+                                                         const char *defname);
+
+/**
+ * Find the node owning this simulation state item.
+ */
+bNode *NOD_geometry_simulation_output_find_node_by_item(struct bNodeTree *ntree,
+                                                        const struct NodeSimulationItem *item);
+
+bool NOD_geometry_simulation_output_contains_item(struct NodeGeometrySimulationOutput *sim,
+                                                  const struct NodeSimulationItem *item);
+struct NodeSimulationItem *NOD_geometry_simulation_output_get_active_item(
+    struct NodeGeometrySimulationOutput *sim);
+void NOD_geometry_simulation_output_set_active_item(struct NodeGeometrySimulationOutput *sim,
+                                                    struct NodeSimulationItem *item);
+struct NodeSimulationItem *NOD_geometry_simulation_output_find_item(
+    struct NodeGeometrySimulationOutput *sim, const char *name);
+struct NodeSimulationItem *NOD_geometry_simulation_output_add_item(
+    struct NodeGeometrySimulationOutput *sim, short socket_type, const char *name);
+struct NodeSimulationItem *NOD_geometry_simulation_output_insert_item(
+    struct NodeGeometrySimulationOutput *sim, short socket_type, const char *name, int index);
+struct NodeSimulationItem *NOD_geometry_simulation_output_add_item_from_socket(
+    struct NodeGeometrySimulationOutput *sim,
+    const struct bNode *from_node,
+    const struct bNodeSocket *from_sock);
+struct NodeSimulationItem *NOD_geometry_simulation_output_insert_item_from_socket(
+    struct NodeGeometrySimulationOutput *sim,
+    const struct bNode *from_node,
+    const struct bNodeSocket *from_sock,
+    int index);
+void NOD_geometry_simulation_output_remove_item(struct NodeGeometrySimulationOutput *sim,
+                                                struct NodeSimulationItem *item);
+void NOD_geometry_simulation_output_clear_items(struct NodeGeometrySimulationOutput *sim);
+void NOD_geometry_simulation_output_move_item(struct NodeGeometrySimulationOutput *sim,
+                                              int from_index,
+                                              int to_index);
 
 /** \} */
 

source/blender/nodes/NOD_socket.h

@@ -22,6 +22,8 @@ struct bNodeTree;
 extern "C" {
 #endif
 
+void node_type_draw_color(const char *idname, float *r_color);
+
 struct bNodeSocket *node_add_socket_from_template(struct bNodeTree *ntree,
                                                   struct bNode *node,
                                                   struct bNodeSocketTemplate *stemp,

source/blender/nodes/geometry/node_geometry_util.hh

@@ -136,8 +136,5 @@ class FieldAtIndexInput final : public bke::GeometryFieldInput {
 void socket_declarations_for_simulation_items(Span<NodeSimulationItem> items,
                                               NodeDeclaration &r_declaration);
 const CPPType &get_simulation_item_cpp_type(const NodeSimulationItem &item);
-/** \warning Return value will be reallocated when items are added or removed. */
-NodeSimulationItem *simulation_item_add_from_socket(NodeGeometrySimulationOutput &storage,
-                                                    const bNodeSocket &socket);
 
 }  // namespace blender::nodes

source/blender/nodes/geometry/nodes/node_geo_simulation_input.cc

@@ -8,6 +8,7 @@
 #include "UI_interface.h"
 #include "UI_resources.h"
 
+#include "NOD_geometry.h"
 #include "NOD_socket.h"
 
 #include "node_geometry_util.hh"
@@ -141,8 +142,8 @@ static bool node_insert_link(bNodeTree *ntree, bNode *node, bNodeLink *link)
 
   if (link->tonode == node) {
     if (link->tosock->identifier == StringRef("__extend__")) {
-      if (const NodeSimulationItem *item = simulation_item_add_from_socket(storage,
-                                                                           *link->fromsock)) {
+      if (const NodeSimulationItem *item = NOD_geometry_simulation_output_add_item_from_socket(
+              &storage, link->fromnode, link->fromsock)) {
         update_node_declaration_and_sockets(*ntree, *node);
         link->tosock = nodeFindSocket(node, SOCK_IN, item->name);
       }
@@ -154,8 +155,8 @@ static bool node_insert_link(bNodeTree *ntree, bNode *node, bNodeLink *link)
   else {
     BLI_assert(link->fromnode == node);
     if (link->fromsock->identifier == StringRef("__extend__")) {
-      if (const NodeSimulationItem *item = simulation_item_add_from_socket(storage,
-                                                                           *link->tosock)) {
+      if (const NodeSimulationItem *item = NOD_geometry_simulation_output_add_item_from_socket(
+              &storage, link->tonode, link->tosock)) {
         update_node_declaration_and_sockets(*ntree, *node);
         link->fromsock = nodeFindSocket(node, SOCK_OUT, item->name);
       }
@@ -185,6 +186,15 @@ void register_node_type_geo_simulation_input()
   nodeRegisterType(&ntype);
 }
 
+bNode *NOD_geometry_simulation_input_get_paired_output(bNodeTree *node_tree,
+                                                       const bNode *simulation_input_node)
+{
+  namespace file_ns = blender::nodes::node_geo_simulation_input_cc;
+
+  const NodeGeometrySimulationInput &data = file_ns::node_storage(*simulation_input_node);
+  return node_tree->node_by_id(data.output_node_id);
+}
+
 bool NOD_geometry_simulation_input_pair_with_output(const bNodeTree *node_tree,
                                                     bNode *sim_input_node,
                                                     const bNode *sim_output_node)

source/blender/nodes/geometry/nodes/node_geo_simulation_output.cc

@@ -8,7 +8,6 @@
 #include "DEG_depsgraph_query.h"
 
 #include "UI_interface.h"
-#include "UI_resources.h"
 
 #include "NOD_common.h"
 #include "NOD_socket.h"
@@ -25,15 +24,15 @@ void socket_declarations_for_simulation_items(const Span<NodeSimulationItem> ite
       case SOCK_GEOMETRY: {
         {
           std::unique_ptr<decl::Geometry> decl = std::make_unique<decl::Geometry>();
-          decl->name = item.name;
-          decl->identifier = item.name;
+          decl->name = item.name ? item.name : "";
+          decl->identifier = "Item_" + std::to_string(item.identifier);
           decl->in_out = SOCK_IN;
           r_declaration.inputs.append(std::move(decl));
         }
         {
           std::unique_ptr<decl::Geometry> decl = std::make_unique<decl::Geometry>();
-          decl->name = item.name;
-          decl->identifier = item.name;
+          decl->name = item.name ? item.name : "";
+          decl->identifier = "Item_" + std::to_string(item.identifier);
           decl->in_out = SOCK_OUT;
           r_declaration.outputs.append(std::move(decl));
         }
@@ -47,13 +46,20 @@ void socket_declarations_for_simulation_items(const Span<NodeSimulationItem> ite
   r_declaration.outputs.append(decl::create_extend_declaration(SOCK_OUT));
 }
 
+struct SimulationItemsUniqueNameArgs {
+  NodeGeometrySimulationOutput *sim;
+  const NodeSimulationItem *item;
+};
+
 static bool simulation_items_unique_name_check(void *arg, const char *name)
 {
-  const NodeGeometrySimulationOutput &storage = *static_cast<const NodeGeometrySimulationOutput *>(
+  const SimulationItemsUniqueNameArgs &args = *static_cast<const SimulationItemsUniqueNameArgs *>(
       arg);
-  for (const NodeSimulationItem &item : Span(storage.items, storage.items_num)) {
-    if (STREQ(item.name, name)) {
-      return true;
+  for (const NodeSimulationItem &item : args.sim->items_span()) {
+    if (&item != args.item) {
+      if (STREQ(item.name, name)) {
+        return true;
+      }
     }
   }
   if (STREQ(name, "Delta Time")) {
@@ -62,37 +68,6 @@ static bool simulation_items_unique_name_check(void *arg, const char *name)
   return false;
 }
 
-NodeSimulationItem *simulation_item_add_from_socket(NodeGeometrySimulationOutput &storage,
-                                                    const bNodeSocket &socket)
-{
-  if (socket.type != SOCK_GEOMETRY) {
-    return nullptr;
-  }
-  char unique_name[MAX_NAME + 4] = "";
-  BLI_uniquename_cb(simulation_items_unique_name_check,
-                    &storage,
-                    socket.name,
-                    '.',
-                    unique_name,
-                    ARRAY_SIZE(unique_name));
-
-  NodeSimulationItem *old_items = storage.items;
-  storage.items = MEM_cnew_array<NodeSimulationItem>(storage.items_num + 1, __func__);
-  for (const int i : IndexRange(storage.items_num)) {
-    storage.items[i].name = old_items[i].name;
-    storage.items[i].socket_type = old_items[i].socket_type;
-  }
-
-  NodeSimulationItem &added_item = storage.items[storage.items_num];
-  added_item.name = BLI_strdup(unique_name);
-  added_item.socket_type = socket.type;
-
-  storage.items_num++;
-  MEM_SAFE_FREE(old_items);
-
-  return &added_item;
-}
-
 const CPPType &get_simulation_item_cpp_type(const NodeSimulationItem &item)
 {
   switch (item.socket_type) {
@@ -272,10 +247,15 @@ static void node_declare_dynamic(const bNodeTree & /*node_tree*/,
 static void node_init(bNodeTree * /*tree*/, bNode *node)
 {
   NodeGeometrySimulationOutput *data = MEM_cnew<NodeGeometrySimulationOutput>(__func__);
+
+  data->next_identifier = 0;
+
   data->items = MEM_cnew_array<NodeSimulationItem>(1, __func__);
   data->items[0].name = BLI_strdup(DATA_("Geometry"));
   data->items[0].socket_type = SOCK_GEOMETRY;
+  data->items[0].identifier = data->next_identifier++;
   data->items_num = 1;
+
   node->storage = data;
 }
 
@@ -299,8 +279,11 @@ static void node_copy_storage(bNodeTree * /*dst_tree*/, bNode *dst_node, const b
 
   dst_storage->items = MEM_cnew_array<NodeSimulationItem>(src_storage.items_num, __func__);
   dst_storage->items_num = src_storage.items_num;
+  dst_storage->active_index = src_storage.active_index;
+  dst_storage->next_identifier = src_storage.next_identifier;
   for (const int i : IndexRange(src_storage.items_num)) {
     if (char *name = src_storage.items[i].name) {
+      dst_storage->items[i].identifier = src_storage.items[i].identifier;
       dst_storage->items[i].name = BLI_strdup(name);
       dst_storage->items[i].socket_type = src_storage.items[i].socket_type;
     }
@@ -314,8 +297,8 @@ static bool node_insert_link(bNodeTree *ntree, bNode *node, bNodeLink *link)
   NodeGeometrySimulationOutput &storage = node_storage(*node);
   if (link->tonode == node) {
     if (link->tosock->identifier == StringRef("__extend__")) {
-      if (const NodeSimulationItem *item = simulation_item_add_from_socket(storage,
-                                                                           *link->fromsock)) {
+      if (const NodeSimulationItem *item = NOD_geometry_simulation_output_add_item_from_socket(
+              &storage, link->fromnode, link->fromsock)) {
         update_node_declaration_and_sockets(*ntree, *node);
         link->tosock = nodeFindSocket(node, SOCK_IN, item->name);
       }
@@ -327,8 +310,8 @@ static bool node_insert_link(bNodeTree *ntree, bNode *node, bNodeLink *link)
   else {
     BLI_assert(link->fromnode == node);
     if (link->fromsock->identifier == StringRef("__extend__")) {
-      if (const NodeSimulationItem *item = simulation_item_add_from_socket(storage,
-                                                                           *link->tosock)) {
+      if (const NodeSimulationItem *item = NOD_geometry_simulation_output_add_item_from_socket(
+              &storage, link->fromnode, link->tosock)) {
         update_node_declaration_and_sockets(*ntree, *node);
         link->fromsock = nodeFindSocket(node, SOCK_OUT, item->name);
       }
@@ -359,3 +342,202 @@ void register_node_type_geo_simulation_output()
                     file_ns::node_copy_storage);
   nodeRegisterType(&ntype);
 }
+
+blender::Span<NodeSimulationItem> NodeGeometrySimulationOutput::items_span() const
+{
+  return blender::Span<NodeSimulationItem>(items, items_num);
+}
+
+blender::MutableSpan<NodeSimulationItem> NodeGeometrySimulationOutput::items_span_for_write()
+{
+  return blender::MutableSpan<NodeSimulationItem>(items, items_num);
+}
+
+blender::IndexRange NodeGeometrySimulationOutput::items_range() const
+{
+  return blender::IndexRange(items_num);
+}
+
+bool NOD_geometry_simulation_output_item_socket_type_supported(
+    const eNodeSocketDatatype socket_type)
+{
+  return ELEM(socket_type, SOCK_GEOMETRY);
+}
+
+bNode *NOD_geometry_simulation_output_find_node_by_item(bNodeTree *ntree,
+                                                        const NodeSimulationItem *item)
+{
+  ntree->ensure_topology_cache();
+  for (bNode *node : ntree->nodes_by_type("GeometryNodeSimulationOutput")) {
+    NodeGeometrySimulationOutput *sim = static_cast<NodeGeometrySimulationOutput *>(node->storage);
+    if (sim->items_span().contains_ptr(item)) {
+      return node;
+    }
+  }
+  return nullptr;
+}
+
+bool NOD_geometry_simulation_output_item_set_unique_name(NodeGeometrySimulationOutput *sim,
+                                                         NodeSimulationItem *item,
+                                                         const char *name,
+                                                         const char *defname)
+{
+  char unique_name[MAX_NAME + 4];
+  BLI_strncpy(unique_name, name, sizeof(unique_name));
+
+  blender::nodes::SimulationItemsUniqueNameArgs args{sim, item};
+  const bool name_changed = BLI_uniquename_cb(blender::nodes::simulation_items_unique_name_check,
+                                              &args,
+                                              defname,
+                                              '.',
+                                              unique_name,
+                                              ARRAY_SIZE(unique_name));
+  item->name = BLI_strdup(unique_name);
+  return name_changed;
+}
+
+bool NOD_geometry_simulation_output_contains_item(NodeGeometrySimulationOutput *sim,
+                                                  const NodeSimulationItem *item)
+{
+  return sim->items_span().contains_ptr(item);
+}
+
+NodeSimulationItem *NOD_geometry_simulation_output_get_active_item(
+    NodeGeometrySimulationOutput *sim)
+{
+  if (!sim->items_range().contains(sim->active_index)) {
+    return nullptr;
+  }
+  return &sim->items[sim->active_index];
+}
+
+void NOD_geometry_simulation_output_set_active_item(NodeGeometrySimulationOutput *sim,
+                                                    NodeSimulationItem *item)
+{
+  if (sim->items_span().contains_ptr(item)) {
+    sim->active_index = item - sim->items;
+  }
+}
+
+NodeSimulationItem *NOD_geometry_simulation_output_find_item(NodeGeometrySimulationOutput *sim,
+                                                             const char *name)
+{
+  for (NodeSimulationItem &item : sim->items_span_for_write()) {
+    if (STREQ(item.name, name)) {
+      return &item;
+    }
+  }
+  return nullptr;
+}
+
+NodeSimulationItem *NOD_geometry_simulation_output_add_item(NodeGeometrySimulationOutput *sim,
+                                                            const short socket_type,
+                                                            const char *name)
+{
+  return NOD_geometry_simulation_output_insert_item(sim, socket_type, name, sim->items_num);
+}
+
+NodeSimulationItem *NOD_geometry_simulation_output_insert_item(NodeGeometrySimulationOutput *sim,
+                                                               const short socket_type,
+                                                               const char *name,
+                                                               int index)
+{
+  NodeSimulationItem *old_items = sim->items;
+  sim->items = MEM_cnew_array<NodeSimulationItem>(sim->items_num + 1, __func__);
+  for (const int i : blender::IndexRange(index)) {
+    sim->items[i] = old_items[i];
+  }
+  for (const int i : blender::IndexRange(index, sim->items_num - index)) {
+    sim->items[i + 1] = old_items[i];
+  }
+
+  const char *defname = nodeStaticSocketLabel(socket_type, 0);
+  NodeSimulationItem &added_item = sim->items[index];
+  added_item.identifier = sim->next_identifier++;
+  NOD_geometry_simulation_output_item_set_unique_name(sim, &added_item, name, defname);
+  added_item.socket_type = socket_type;
+
+  sim->items_num++;
+  MEM_SAFE_FREE(old_items);
+
+  return &added_item;
+}
+
+NodeSimulationItem *NOD_geometry_simulation_output_add_item_from_socket(
+    NodeGeometrySimulationOutput *sim, const bNode * /*from_node*/, const bNodeSocket *from_sock)
+{
+  if (from_sock->type != SOCK_GEOMETRY) {
+    return nullptr;
+  }
+  return NOD_geometry_simulation_output_insert_item(
+      sim, from_sock->type, from_sock->name, sim->items_num);
+}
+
+NodeSimulationItem *NOD_geometry_simulation_output_insert_item_from_socket(
+    NodeGeometrySimulationOutput *sim,
+    const bNode * /*from_node*/,
+    const bNodeSocket *from_sock,
+    int index)
+{
+  return NOD_geometry_simulation_output_insert_item(sim, from_sock->type, from_sock->name, index);
+}
+
+void NOD_geometry_simulation_output_remove_item(NodeGeometrySimulationOutput *sim,
+                                                NodeSimulationItem *item)
+{
+  const int index = item - sim->items;
+  if (index < 0 || index >= sim->items_num) {
+    return;
+  }
+
+  NodeSimulationItem *old_items = sim->items;
+  sim->items = MEM_cnew_array<NodeSimulationItem>(sim->items_num - 1, __func__);
+  for (const int i : blender::IndexRange(index)) {
+    sim->items[i] = old_items[i];
+  }
+  for (const int i : blender::IndexRange(index, sim->items_num - index).drop_front(1)) {
+    sim->items[i - 1] = old_items[i];
+  }
+
+  MEM_SAFE_FREE(old_items[index].name);
+
+  sim->items_num--;
+  MEM_SAFE_FREE(old_items);
+}
+
+void NOD_geometry_simulation_output_clear_items(struct NodeGeometrySimulationOutput *sim)
+{
+  for (NodeSimulationItem &item : sim->items_span_for_write()) {
+    MEM_SAFE_FREE(item.name);
+  }
+  MEM_SAFE_FREE(sim->items);
+  sim->items = nullptr;
+  sim->items_num = 0;
+}
+
+void NOD_geometry_simulation_output_move_item(NodeGeometrySimulationOutput *sim,
+                                              int from_index,
+                                              int to_index)
+{
+  BLI_assert(from_index >= 0 && from_index < sim->items_num);
+  BLI_assert(to_index >= 0 && to_index < sim->items_num);
+
+  if (from_index == to_index) {
+    return;
+  }
+
+  if (from_index < to_index) {
+    const NodeSimulationItem tmp = sim->items[from_index];
+    for (int i = from_index; i < to_index; ++i) {
+      sim->items[i] = sim->items[i + 1];
+    }
+    sim->items[to_index] = tmp;
+  }
+  else /* from_index > to_index */ {
+    const NodeSimulationItem tmp = sim->items[from_index];
+    for (int i = from_index; i > to_index; --i) {
+      sim->items[i] = sim->items[i - 1];
+    }
+    sim->items[to_index] = tmp;
+  }
+}

source/blender/nodes/intern/node_socket.cc

@@ -39,6 +39,13 @@ using namespace blender;
 using blender::fn::ValueOrField;
 using blender::nodes::SocketDeclarationPtr;
 
+extern "C" void ED_node_type_draw_color(const char *idname, float *r_color);
+
+void node_type_draw_color(const char *idname, float *r_color)
+{
+  ED_node_type_draw_color(idname, r_color);
+}
+
 struct bNodeSocket *node_add_socket_from_template(struct bNodeTree *ntree,
                                                   struct bNode *node,
                                                   struct bNodeSocketTemplate *stemp,