Add the inputs for the interface

The only missing part is joining the instances

@@ -237,2 +237,4 @@
                                                     const GeometryComponent &component)>;
 
+  bool attribute_foreach(Span<GeometryComponent::Type> component_types,
+                         bool include_instances,

@@ -238,1 +238,4 @@
 
+  bool attribute_foreach(Span<GeometryComponent::Type> component_types,
+                         bool include_instances,
+                         const int current_depth,

@@ -239,0 +239,4 @@
+  bool attribute_foreach(Span<GeometryComponent::Type> component_types,
+                         bool include_instances,
+                         const int current_depth,
+                         const int depth_target,

@@ -251,6 +259,14 @@ struct GeometrySet {
                                          const AnonymousAttributePropagationInfo &propagation_info,
                                          Map<AttributeIDRef, AttributeKind> &r_attributes) const;
 
+  void gather_attributes_for_propagation(Span<GeometryComponent::Type> component_types,

@@ -576,0 +594,4 @@
+   * - callback: Callback function for attribute processing.
+   */
+  
+  //  Initialize flag to track if child instances have the specified components.

@@ -576,0 +604,4 @@
+    // Iterate over instances based on the selection index mask.
+    const Instances &instances = *this->get_instances();
+    // ensure objects and collection are included.
+    Instances ensure_instances = instances;

@@ -576,0 +606,4 @@
+    // ensure objects and collection are included.
+    Instances ensure_instances = instances;
+    ensure_instances.ensure_geometry_instances();
+    const IndexMask indices = (current_depth == 0) ? selection : IndexMask(IndexRange(ensure_instances.instances_num()));

@@ -576,0 +625,4 @@
+  // Flag to track if any relevant attributes were found.
+  bool is_relevant = false;
+
+  // Iterate over specified component types.

@@ -576,0 +627,4 @@
+
+  // Iterate over specified component types.
+  for (const GeometryComponent::Type component_type : component_types) {
+    // Skip if the component type is not present.

@@ -576,0 +634,4 @@
+
+    // Check for a special instance condition.
+    const bool is_special_instance = (component_type == GeometryComponent::Type::Instance) && (component_types.size() > 1);
+    if (is_special_instance && !is_child_has_component) {

@@ -14,1 +14,4 @@
 
+void join_attributes(const Span<const bke::GeometryComponent *> src_components,
+                            bke::GeometryComponent &result,
+                            const Span<StringRef> ignored_attributes);

@@ -185,6 +185,9 @@ static void join_component_type(const bke::GeometryComponent::Type component_typ
   options.keep_original_ids = true;
   options.realize_instance_attributes = false;
   options.propagation_info = propagation_info;
+  options.depths = VArray<int>::ForSingle( 99, instances.get()->instances_num());

@@ -286,3 +314,4 @@
   }
 };
 
+static void realize_collections(Collection *collection, bke::Instances* instances){

@@ -477,3 +529,1 @@
-        index++;
-      }
-      FOREACH_COLLECTION_OBJECT_RECURSIVE_END;
+      Collection *collection_ptr = &reference.collection();

@@ -480,0 +531,4 @@
+      realize_collections(collection_ptr, instances.get());
+      const bke::GeometrySet colleciton_geometry = bke::GeometrySet::from_instances(instances.release());
+      /* important as otherwise the Instances pointer would be deleted with the GeomtrySet*/
+      colleciton_geometry.get_component(bke::GeometryComponent::Type::Instance)->add_user(); 

@@ -41,0 +71,4 @@
+ * output will contain an `id` attribute as well. The output id is generated by mixing/hashing ids
+ * of instances and of the instanced geometry data.
+ *
+ * Will realize only the instances chosen by varied_depth_option to there chosen depth.

@@ -1581,0 +1973,4 @@
+  all_instances.depths = VArray<int>::ForSingle(VariedDepthOption::MAX_DEPTH,
+                                                geometry_set.get_instances()->instances_num());
+  IndexMaskMemory memory;
+  all_instances.selection = IndexMask::from_bools(

@@ -16,0 +18,4 @@
+  b.add_input<decl::Bool>("Selection")
+      .default_value(true)
+      .hide_value()
+      .supports_field()

@@ -23,0 +49,4 @@
+
+  static auto selection_override = mf::build::SI2_SO<int, bool, bool>(
+      "selection_override",
+      [](int value, bool selection) { return value == 0 ? false : selection; },

@@ -23,0 +53,4 @@
+      mf::build::exec_presets::AllSpanOrSingle());
+
+  Field<int> depth_field_overrided(
+      FieldOperation::Create(depth_override, {depth_field, realize_all_filed}));

@@ -23,0 +66,4 @@
+  evaluator.evaluate();
+
+  geometry::VariedDepthOption varied_depth_option;
+  varied_depth_option.depths = evaluator.get_evaluated<int>(evaluated_depth_index);

@@ -77,2 +76,2 @@
-                            GeometryComponent &result,
-                            const Span<StringRef> ignored_attributes = {})
+void join_attributes(const Span<const GeometryComponent *> src_components,
+                     const Span<StringRef> ignored_attributes,

@@ -474,40 +543,14 @@ static void foreach_geometry_in_reference(
     FunctionRef<void(const bke::GeometrySet &geometry_set, const float4x4 &transform, uint32_t id)>
         fn)
 {
-  switch (reference.type()) {

@@ -226,2 +220,4 @@
 };
 
+struct AllInstancesInfo {
+  /** store an array of void pointer to attributes for each component. */

@@ -463,6 +500,38 @@ static Vector<std::pair<int, GSpan>> prepare_attribute_fallbacks(
   return attributes_to_override;
 }
 
+static bke::GeometrySet &geometry_set_from_reference(const InstanceReference &reference,

@@ -466,0 +524,4 @@
+      r_geometry_set = bke::GeometrySet();  // Return an empty GeometrySet for None type
+      break;
+    }
+    default: {

@@ -679,0 +794,4 @@
+    }
+  }
+
+  /*Flag to track if any relevant attributes were found.*/

@@ -679,0 +828,4 @@
+ * Specialized for Specialized attribute_foreach to get:
+ * current_depth, depth_target, instance_depth and selection.
+ */
+void static gather_attributes_for_propagation(

@@ -679,0 +951,4 @@
+    bke::AttributeIDRef id = all_instances_attributes.ids[attribute_index];
+    eCustomDataType type = all_instances_attributes.kinds[attribute_index].data_type;
+    blender::bke::MutableAttributeAccessor attr = dst_instances->attributes_for_write();
+    attr.lookup_or_add_for_write_only_span(id, domain, type).finish();

@@ -16,0 +23,4 @@
+  b.add_input<decl::Bool>("Realize All")
+      .default_value(true)
+      .field_on_all()
+      .description("Determine wether to realize nested instances completly");

@@ -28,0 +31,4 @@
+/**
+ * Allow  the user to choice which instances to realize and to what depth.
+ */
+struct VariedDepthOption {

@@ -304,6 +320,25 @@ static int64_t get_final_points_num(const GatherTasks &tasks)
   return points_num;
 }
 
+static void realize_collections(Collection *collection, bke::Instances *instances)

@@ -307,0 +326,4 @@
+    float4x4 transform = float4x4::identity();
+    transform.location() += float3((collection_child->collection)->instance_offset);
+    transform.location() -= float3(collection->instance_offset);
+    const int handle = instances->add_reference(*(collection_child->collection));

@@ -378,3 +413,3 @@
 }
 
-static void create_result_ids(const RealizeInstancesOptions &options,
+static void create_result_ids(bool keep_original_ids,

@@ -466,0 +507,4 @@
+      const Object &object = reference.object();
+      const bke::GeometrySet geometry_set = bke::object_get_evaluated_geometry_set(object);
+      return geometry_set;
+      break;

@@ -535,2 +578,3 @@
 
-  for (const int i : transforms.index_range()) {
+  /* If at top level, get instance indices from selection field, else use all instances. */
+  const IndexMask indices = current_depth == 0 ? gather_info.selection :

@@ -537,0 +579,4 @@
+  /* If at top level, get instance indices from selection field, else use all instances. */
+  const IndexMask indices = current_depth == 0 ? gather_info.selection :
+                                                 IndexMask(IndexRange(instances.instances_num()));
+  for (const int mask_index : indices.index_range()) {

@@ -537,0 +583,4 @@
+    const int i = indices[mask_index];
+
+    /* If at top level, retrieve depth from gather_info, else continue with target_depth. */
+    const int depth_target = current_depth == 0 ? gather_info.depths[i] : target_depth;

@@ -679,0 +758,4 @@
+                              const Span<bke::GeometryComponent::Type> component_types,
+                              const int current_depth,
+                              const int depth_target,
+                              const VArray<int> instance_depth,

@@ -679,0 +764,4 @@
+{
+
+  /* Initialize flag to track if child instances have the specified components.*/
+  bool child_has_component = true;

@@ -679,0 +773,4 @@
+    const IndexMask indices = (0 == current_depth) ?
+                                  selection :
+                                  IndexMask(IndexRange(instances.instances_num()));
+    for (const int index : indices.index_range()) {

@@ -679,0 +775,4 @@
+                                  IndexMask(IndexRange(instances.instances_num()));
+    for (const int index : indices.index_range()) {
+      const int i = indices[index];
+      const int depth_target_tmp = (0 == current_depth) ? instance_depth[i] : depth_target;

@@ -679,0 +780,4 @@
+          instances.references()[instances.reference_handles()[i]]);
+      /* Process child instances with a recursive call.*/
+      if (current_depth != depth_target_tmp) {
+        child_has_component = child_has_component | attribute_foreach(instance_geometry_set,

@@ -679,0 +792,4 @@
+  }
+
+  /* Flag to track if any relevant attributes were found.*/
+  bool is_relevant = false;

@@ -679,0 +796,4 @@
+
+  for (const bke::GeometryComponent::Type component_type : component_types) {
+    if (geometry_set.has(component_type)) {
+      /* Check if the current instance components is the main one*/

@@ -679,0 +797,4 @@
+  for (const bke::GeometryComponent::Type component_type : component_types) {
+    if (geometry_set.has(component_type)) {
+      /* Check if the current instance components is the main one*/
+      const bool is_special_instance = (bke::GeometryComponent::Type::Instance ==

@@ -679,0 +811,4 @@
+                return true;
+              });
+
+          is_relevant = true;

@@ -679,0 +826,4 @@
+ * current_depth, depth_target, instance_depth and selection.
+ */
+static void gather_attributes_for_propagation(
+    bke::GeometrySet re_geometry_set,

@@ -679,0 +907,4 @@
+                                    options.propagation_info,
+                                    attributes_to_propagate);
+  attributes_to_propagate.remove("position");
+  attributes_to_propagate.remove("radius");

@@ -679,0 +930,4 @@
+    return;
+  }
+
+  VArray<blender::float4x4>::ForSpan(src_base_transforms);

@@ -679,0 +959,4 @@
+    const bke::InstancesComponent &src_component = static_cast<const bke::InstancesComponent &>(
+        *src_components[component_index]);
+    const bke::Instances &src_instances = *src_component.get();
+    const blender::float4x4 src_base_transform = src_base_transforms[component_index];

@@ -679,0 +960,4 @@
+        *src_components[component_index]);
+    const bke::Instances &src_instances = *src_component.get();
+    const blender::float4x4 src_base_transform = src_base_transforms[component_index];
+    const Array<const void *> attribute_fallback_array = attribute_fallback[component_index].array;

@@ -679,0 +969,4 @@
+    }
+    const IndexRange dst_range = offsets[component_index];
+    for (const int attribute_index : all_instances_attributes.index_range()) {
+      bke::AttributeIDRef id = all_instances_attributes.ids[attribute_index];

@@ -679,0 +977,4 @@
+          dst_instances->attributes_for_write().lookup_for_write_span(id);
+      GMutableSpan dst_span = write_attribute.span;
+
+      if (!write_attribute) {  // do not override existing attributes

@@ -679,0 +990,4 @@
+      }
+
+      GVArray src_span = GVArray::ForSingle(*cpp_type, dst_range.size(), attribute_ptr);
+      array_utils::copy(src_span, dst_span.slice(dst_range));

@@ -679,0 +1007,4 @@
+  auto &dst_component = r_realized_geometry.get_component_for_write<bke::InstancesComponent>();
+
+  Vector<const bke::GeometryComponent *> for_join_attributes;
+  for (bke::GeometryComponentPtr compent : src_components) {

@@ -679,0 +1011,4 @@
+    for_join_attributes.append(compent.get());
+  }
+
+  join_attributes(

@@ -771,3 +1118,3 @@
 
 static void execute_realize_pointcloud_task(
-    const RealizeInstancesOptions &options,
+    bool keep_original_ids,

@@ -1597,0 +1957,4 @@
+ */
+static void propagate_instances_to_keep(
+    const bke::GeometrySet &geometry_set,
+    IndexMask selection,

@@ -23,0 +49,4 @@
+      [](int depth, bool realize_all_field) {
+        return realize_all_field ? geometry::VariedDepthOption::MAX_DEPTH : std::max(depth, 0);
+      },
+      mf::build::exec_presets::AllSpanOrSingle());

@@ -23,0 +51,4 @@
+      },
+      mf::build::exec_presets::AllSpanOrSingle());
+
+  Field<int> depth_field_overrided(FieldOperation::Create(

@@ -679,0 +820,4 @@
+ * current_depth, depth_target, instance_depth and selection.
+ */
+static void gather_attributes_for_propagation(
+    bke::GeometrySet geometry_set,

@@ -23,0 +49,4 @@
+      [](int depth, bool realize_all_field) {
+        return realize_all_field ? geometry::VariedDepthOptions::MAX_DEPTH : std::max(depth, 0);
+      },
+      mf::build::exec_presets::Materialized());

@@ -466,0 +520,4 @@
+      return geometry_set;
+    }
+    case InstanceReference::Type::None: {
+      return {};  // Return an empty GeometrySet for None type

@@ -679,0 +789,4 @@
+
+  for (const bke::GeometryComponent::Type component_type : component_types) {
+    if (geometry_set.has(component_type)) {
+      /*Check if the current instance component is the selected one. Instances are handled