GPv3: Named Layer Selection node

This node supports either a Layer or a Layer Group name as input,
and outputs a selection field for it.

Known limitations to be addressed separately:

* We are not warning/keeping track of the named layers.
* There is no lookup for layers (groups) yet.

Ref !113908.

Pull Request: https://projects.blender.org/blender/blender/pulls/113908

scripts/startup/bl_ui/node_add_menu_geometry.py

@@ -286,6 +286,8 @@ class NODE_MT_geometry_node_GEO_INPUT_SCENE(Menu):
         node_add_menu.add_node_type(layout, "GeometryNodeCollectionInfo")
         node_add_menu.add_node_type(layout, "GeometryNodeImageInfo")
         node_add_menu.add_node_type(layout, "GeometryNodeIsViewport")
+        if context.preferences.experimental.use_grease_pencil_version3:
+            node_add_menu.add_node_type(layout, "GeometryNodeInputNamedLayerSelection")
         node_add_menu.add_node_type(layout, "GeometryNodeObjectInfo")
         node_add_menu.add_node_type(layout, "GeometryNodeInputSceneTime")
         node_add_menu.add_node_type(layout, "GeometryNodeSelfObject")

source/blender/blenkernel/BKE_node.h

@@ -1315,6 +1315,7 @@ void BKE_nodetree_remove_layer_n(struct bNodeTree *ntree, struct Scene *scene, i
 #define GEO_NODE_POINTS_TO_CURVES 2114
 #define GEO_NODE_INPUT_EDGE_SMOOTH 2115
 #define GEO_NODE_SPLIT_TO_INSTANCES 2116
+#define GEO_NODE_INPUT_NAMED_LAYER_SELECTION 2117
 
 /** \} */
 

source/blender/nodes/NOD_static_types.h

@@ -353,6 +353,7 @@ DefNode(GeometryNode, GEO_NODE_INPUT_MESH_FACE_NEIGHBORS, 0, "MESH_FACE_NEIGHBOR
 DefNode(GeometryNode, GEO_NODE_INPUT_MESH_ISLAND, 0, "MESH_ISLAND", InputMeshIsland, "Mesh Island", "Retrieve information about separate connected regions in a mesh")
 DefNode(GeometryNode, GEO_NODE_INPUT_MESH_VERTEX_NEIGHBORS, 0, "MESH_VERTEX_NEIGHBORS", InputMeshVertexNeighbors, "Vertex Neighbors", "Retrieve topology information relating to each vertex of a mesh")
 DefNode(GeometryNode, GEO_NODE_INPUT_NAMED_ATTRIBUTE, 0, "INPUT_ATTRIBUTE", InputNamedAttribute, "Named Attribute", "Retrieve the data of a specified attribute")
+DefNode(GeometryNode, GEO_NODE_INPUT_NAMED_LAYER_SELECTION, 0, "INPUT_NAMED_LAYER_SELECTION", InputNamedLayerSelection, "Named Layer Selection", "Output a selection of a grease pencil layer");
 DefNode(GeometryNode, GEO_NODE_INPUT_NORMAL, 0, "INPUT_NORMAL", InputNormal, "Normal", "Retrieve a unit length vector indicating the direction pointing away from the geometry at each element")
 DefNode(GeometryNode, GEO_NODE_INPUT_POSITION, 0, "POSITION", InputPosition, "Position", "Retrieve a vector indicating the location of each element")
 DefNode(GeometryNode, GEO_NODE_INPUT_RADIUS, 0, "INPUT_RADIUS", InputRadius, "Radius", "Retrieve the radius at each point on curve or point cloud geometry")

source/blender/nodes/geometry/CMakeLists.txt

@@ -101,6 +101,7 @@ set(SRC
   nodes/node_geo_input_mesh_island.cc
   nodes/node_geo_input_mesh_vertex_neighbors.cc
   nodes/node_geo_input_named_attribute.cc
+  nodes/node_geo_input_named_layer_selection.cc
   nodes/node_geo_input_normal.cc
   nodes/node_geo_input_position.cc
   nodes/node_geo_input_radius.cc

source/blender/nodes/geometry/nodes/node_geo_input_named_layer_selection.cc

@@ -0,0 +1,50 @@
+/* SPDX-FileCopyrightText: 2023 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "BKE_geometry_fields.hh"
+
+#include "node_geometry_util.hh"
+
+namespace blender::nodes::node_geo_input_named_layer_selection__cc {
+
+static void node_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::String>("Name");
+  b.add_output<decl::Bool>("Selection").field_source_reference_all();
+}
+
+static void node_geo_exec(GeoNodeExecParams params)
+{
+  std::string name = params.extract_input<std::string>("Name");
+  if (name.empty()) {
+    params.set_default_remaining_outputs();
+    return;
+  }
+
+  Field<bool> selection_field{
+      std::make_shared<bke::NamedLayerSelectionFieldInput>(std::move(name))};
+  params.set_output("Selection", std::move(selection_field));
+}
+
+static void search_link_ops(GatherLinkSearchOpParams &params)
+{
+  if (U.experimental.use_grease_pencil_version3) {
+    nodes::search_link_ops_for_basic_node(params);
+  }
+}
+
+static void node_register()
+{
+  static bNodeType ntype;
+
+  geo_node_type_base(
+      &ntype, GEO_NODE_INPUT_NAMED_LAYER_SELECTION, "Named Layer Selection", NODE_CLASS_INPUT);
+  ntype.declare = node_declare;
+  ntype.geometry_node_execute = node_geo_exec;
+  ntype.gather_link_search_ops = search_link_ops;
+  nodeRegisterType(&ntype);
+}
+NOD_REGISTER_NODE(node_register)
+
+}  // namespace blender::nodes::node_geo_input_named_layer_selection__cc