Support adding non-geometry sockets to simulation zone items.

Simulation input/output dependencies can create dependency cycles that
take several passes to resolve. New passes are only scheduled when
the field state actually changes, so once input and output agree on a
minimum viable field state the updates are complete.

@@ -259,0 +269,4 @@
+ * Afterwards both field states will be the same.
+ * @return eFieldStateSyncResult flags indicating which field states have changed.
+ */
+static int sync_field_states(SocketFieldState &a, SocketFieldState &b)

@@ -259,0 +267,4 @@
+/**
+ * Compare both field states and select the most compatible.
+ * Afterwards both field states will be the same.
+ * @return eFieldStateSyncResult flags indicating which field states have changed.

@@ -259,0 +271,4 @@
+ */
+static int sync_field_states(SocketFieldState &a, SocketFieldState &b)
+{
+  int res = 0;

@@ -447,0 +603,4 @@
+
+      /* Find reverse dependencies and resolve conflicts, which may require another pass. */
+      if (propagate_special_data_requirements(tree, *node, field_state_by_socket_id))
+      {

@@ -15,0 +19,4 @@
+{
+  T *data = params.try_get_input_data_ptr_or_request<T>(index);
+  if (data != nullptr) {
+    params.set_output(index + 1, std::move(*data));

@@ -15,0 +77,4 @@
+                                             int index,
+                                             const bke::sim::SimulationStateItem &state_item)
+{
+  if (auto *typed_state_item = dynamic_cast<const bke::sim::TypedSimulationStateItem<T> *>(

@@ -15,0 +84,4 @@
+}
+
+static void copy_next_simulation_state(lf::Params &params,
+                                       int index,

@@ -15,0 +85,4 @@
+
+static void copy_next_simulation_state(lf::Params &params,
+                                       int index,
+                                       short socket_type,

@@ -96,14 +136,142 @@ NodeSimulationItem *simulation_item_add_from_socket(NodeGeometrySimulationOutput
 const CPPType &get_simulation_item_cpp_type(const NodeSimulationItem &item)
 {
   switch (item.socket_type) {
+    case SOCK_FLOAT:

@@ -15,2 +15,3 @@
 
-class GeometrySimulationStateItem : public SimulationStateItem {
+template <typename T>
+class TypedSimulationStateItem : public SimulationStateItem {

@@ -20,2 +24,3 @@
  public:
-  GeometrySimulationStateItem(GeometrySet geometry) : geometry_(std::move(geometry)) {}
+  TypedSimulationStateItem() = default;
+  TypedSimulationStateItem(const T &data)

@@ -22,0 +35,4 @@
+  TypedSimulationStateItem(const U &data)
+  {
+    data_ = data;
+  }

@@ -259,0 +337,4 @@
+{
+  int res = 0;
+  for (const int i : output_node.input_sockets().index_range()) {
+    const bNodeSocket *input_socket = input_node.input_sockets()[i];

@@ -329,0 +471,4 @@
+
+      /* Find reverse dependencies and resolve conflicts, which may require another pass. */
+      if (propagate_special_data_requirements(tree, *node, field_state_by_socket_id))
+      {

@@ -107,0 +254,4 @@
+      copy_typed_simulation_state_output<GeometrySet>(params, index, state_item);
+      break;
+    case SOCK_COLLECTION:
+      copy_typed_simulation_state_output<Collection *>(params, index, state_item);

@@ -157,2 +157,4 @@
    * single value. */
   bool requires_single = false;
+
+  bool operator==(const SocketFieldState &other)

@@ -257,2 +257,4 @@
 }
 
+/** Result of syncing two field states. */
+enum eFieldStateSyncResult {

@@ -259,0 +275,4 @@
+  const bool requires_single = a.requires_single || b.requires_single;
+  const bool is_single = a.is_single && b.is_single;
+
+  eFieldStateSyncResult res = static_cast<eFieldStateSyncResult>(0);

@@ -259,0 +327,4 @@
+    const NodeGeometrySimulationInput &data = *static_cast<NodeGeometrySimulationInput *>(
+        node.storage);
+    if (const bNode *output_node = tree.node_by_id(data.output_node_id)) {
+      eFieldStateSyncResult sync_result = simulation_nodes_field_state_sync(

@@ -266,2 +361,2 @@
-  for (const bNode *node : toposort_result) {
-    const FieldInferencingInterface &inferencing_interface = *interface_by_node[node->index()];
+  while (true) {
+    /* Node updates may require sevaral passes due to cyclic dependencies. */

@@ -15,0 +44,4 @@
+    params.set_output(index + 1, src);
+  }
+  else {
+    //  if (const void *src = state_item.data()) {

@@ -82,0 +122,4 @@
+          copy_next_simulation_state(
+              params,
+              i,
+              static_cast<eNodeSocketDatatype>(simulation_items_[i].socket_type),

@@ -66,3 +109,3 @@
                                                     const bNodeSocket &socket)
 {
-  if (socket.type != SOCK_GEOMETRY) {
+  if (!is_simulation_item_type_supported(static_cast<eNodeSocketDatatype>(socket.type))) {

@@ -259,0 +331,4 @@
+    if (const bNode *output_node = tree.node_by_id(data.output_node_id)) {
+      const eFieldStateSyncResult sync_result = simulation_nodes_field_state_sync(
+          node, *output_node, field_state_by_socket_id);
+      if ((bool)(sync_result & eFieldStateSyncResult::CHANGED_B)) {

@@ -15,0 +29,4 @@
+  }
+}
+
+static void copy_next_simulation_state(lf::Params &params,

@@ -15,0 +36,4 @@
+{
+  const CPPType &cpptype = get_simulation_item_cpp_type(socket_type);
+
+  /* TODO */