Geometry Nodes: add utility to access logged primitive values

source/blender/nodes/NOD_geometry_nodes_log.hh

@@ -304,6 +304,23 @@ class GeoTreeLog {
   void ensure_debug_messages();
 
   ValueLog *find_socket_value_log(const bNodeSocket &query_socket);
+  [[nodiscard]] bool try_convert_primitive_socket_value(const GenericValueLog &value_log,
+                                                        const CPPType &dst_type,
+                                                        void *dst);
+
+  template<typename T>
+  std::optional<T> find_primitive_socket_value(const bNodeSocket &query_socket)
+  {
+    if (auto *value_log = dynamic_cast<GenericValueLog *>(
+            this->find_socket_value_log(query_socket)))
+    {
+      T value;
+      if (this->try_convert_primitive_socket_value(*value_log, CPPType::get<T>(), &value)) {
+        return value;
+      }
+    }
+    return std::nullopt;
+  }
 };
 
 /**

source/blender/nodes/intern/geometry_nodes_log.cc

@@ -9,6 +9,7 @@
 #include "BKE_curves.hh"
 #include "BKE_node_runtime.hh"
 #include "BKE_node_socket_value.hh"
+#include "BKE_type_conversions.hh"
 #include "BKE_volume.hh"
 #include "BKE_volume_openvdb.hh"
 
@@ -484,6 +485,24 @@ ValueLog *GeoTreeLog::find_socket_value_log(const bNodeSocket &query_socket)
   return nullptr;
 }
 
+bool GeoTreeLog::try_convert_primitive_socket_value(const GenericValueLog &value_log,
+                                                    const CPPType &dst_type,
+                                                    void *dst)
+{
+  const void *src_value = value_log.value.get();
+  if (!src_value) {
+    return false;
+  }
+  const bke::DataTypeConversions &conversions = bke::get_implicit_type_conversions();
+  const CPPType &src_type = *value_log.value.type();
+  if (!conversions.is_convertible(src_type, dst_type) && src_type != dst_type) {
+    return false;
+  }
+  dst_type.destruct(dst);
+  conversions.convert_to_uninitialized(src_type, dst_type, src_value, dst);
+  return true;
+}
+
 GeoTreeLogger &GeoModifierLog::get_local_tree_logger(const ComputeContext &compute_context)
 {
   LocalData &local_data = data_per_thread_.local();