Geometry Nodes: Edge Neighbors Node

Creates a new Edge Neighbors node which outputs a field
containing the number of faces connected to each edge.

Differential Revision: https://developer.blender.org/D13493

release/scripts/startup/nodeitems_builtins.py

@@ -150,6 +150,7 @@ def mesh_node_items(context):
     yield NodeItem("GeometryNodeSubdivisionSurface")
     yield NodeItem("GeometryNodeTriangulate")
     yield NodeItemCustom(draw=lambda self, layout, context: layout.separator())
+    yield NodeItem("GeometryNodeInputMeshEdgeNeighbors")
     yield NodeItem("GeometryNodeInputMeshEdgeVertices")
     yield NodeItem("GeometryNodeInputMeshFaceArea")
     yield NodeItem("GeometryNodeInputMeshFaceNeighbors")

source/blender/blenkernel/BKE_node.h

@@ -1716,6 +1716,7 @@ int ntreeTexExecTree(struct bNodeTree *ntree,
 #define GEO_NODE_INPUT_MESH_FACE_NEIGHBORS 1140
 #define GEO_NODE_INPUT_MESH_VERTEX_NEIGHBORS 1141
 #define GEO_NODE_GEOMETRY_TO_INSTANCE 1142
+#define GEO_NODE_INPUT_MESH_EDGE_NEIGHBORS 1143
 /** \} */
 
 /* -------------------------------------------------------------------- */

source/blender/blenkernel/intern/node.cc

@@ -5807,6 +5807,7 @@ static void registerGeometryNodes()
   register_node_type_geo_input_index();
   register_node_type_geo_input_material_index();
   register_node_type_geo_input_material();
+  register_node_type_geo_input_mesh_edge_neighbors();
   register_node_type_geo_input_mesh_edge_vertices();
   register_node_type_geo_input_mesh_face_area();
   register_node_type_geo_input_mesh_face_neighbors();

source/blender/nodes/NOD_geometry.h

@@ -105,6 +105,7 @@ void register_node_type_geo_input_id(void);
 void register_node_type_geo_input_index(void);
 void register_node_type_geo_input_material_index(void);
 void register_node_type_geo_input_material(void);
+void register_node_type_geo_input_mesh_edge_neighbors(void);
 void register_node_type_geo_input_mesh_edge_vertices(void);
 void register_node_type_geo_input_mesh_face_area(void);
 void register_node_type_geo_input_mesh_face_neighbors(void);

source/blender/nodes/NOD_static_types.h

@@ -358,6 +358,7 @@ DefNode(GeometryNode, GEO_NODE_INPUT_ID, 0, "INPUT_ID", InputID, "ID", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_INDEX, 0, "INDEX", InputIndex, "Index", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_MATERIAL_INDEX, 0, "INPUT_MATERIAL_INDEX", InputMaterialIndex, "Material Index", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_MATERIAL, def_geo_input_material, "INPUT_MATERIAL", InputMaterial, "Material", "")
+DefNode(GeometryNode, GEO_NODE_INPUT_MESH_EDGE_NEIGHBORS, 0, "MESH_EDGE_NEIGHBORS", InputMeshEdgeNeighbors, "Edge Neighbors", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_MESH_EDGE_VERTICES, 0, "MESH_EDGE_VERTICES", InputMeshEdgeVertices, "Edge Vertices", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_MESH_FACE_AREA, 0, "MESH_FACE_AREA", InputMeshFaceArea, "Face Area", "")
 DefNode(GeometryNode, GEO_NODE_INPUT_MESH_FACE_NEIGHBORS, 0, "MESH_FACE_NEIGHBORS", InputMeshFaceNeighbors, "Face Neighbors", "")

source/blender/nodes/geometry/CMakeLists.txt

@@ -123,6 +123,7 @@ set(SRC
   nodes/node_geo_input_index.cc
   nodes/node_geo_input_material_index.cc
   nodes/node_geo_input_material.cc
+  nodes/node_geo_input_mesh_edge_neighbors.cc
   nodes/node_geo_input_mesh_edge_vertices.cc
   nodes/node_geo_input_mesh_face_area.cc
   nodes/node_geo_input_mesh_face_neighbors.cc

source/blender/nodes/geometry/nodes/node_geo_input_mesh_edge_neighbors.cc

@@ -0,0 +1,93 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+
+#include "BKE_mesh.h"
+
+#include "node_geometry_util.hh"
+
+namespace blender::nodes::node_geo_input_mesh_edge_neighbors_cc {
+
+static void node_declare(NodeDeclarationBuilder &b)
+{
+  b.add_output<decl::Int>(N_("Face Count"))
+      .field_source()
+      .description(N_("Number of faces that contain the edge"));
+}
+
+class EdgeNeighborCountFieldInput final : public GeometryFieldInput {
+ public:
+  EdgeNeighborCountFieldInput()
+      : GeometryFieldInput(CPPType::get<int>(), "Edge Neighbor Count Field")
+  {
+    category_ = Category::Generated;
+  }
+
+  GVArray get_varray_for_context(const GeometryComponent &component,
+                                 const AttributeDomain domain,
+                                 IndexMask UNUSED(mask)) const final
+  {
+    if (component.type() == GEO_COMPONENT_TYPE_MESH) {
+      const MeshComponent &mesh_component = static_cast<const MeshComponent &>(component);
+      const Mesh *mesh = mesh_component.get_for_read();
+      if (mesh == nullptr) {
+        return {};
+      }
+
+      Array<int> face_count(mesh->totedge, 0);
+      for (const int i : IndexRange(mesh->totloop)) {
+        face_count[mesh->mloop[i].e]++;
+      }
+
+      return mesh_component.attribute_try_adapt_domain<int>(
+          VArray<int>::ForContainer(std::move(face_count)), ATTR_DOMAIN_EDGE, domain);
+    }
+    return {};
+  }
+
+  uint64_t hash() const override
+  {
+    /* Some random constant hash. */
+    return 985671075;
+  }
+
+  bool is_equal_to(const fn::FieldNode &other) const override
+  {
+    return dynamic_cast<const EdgeNeighborCountFieldInput *>(&other) != nullptr;
+  }
+};
+
+static void node_geo_exec(GeoNodeExecParams params)
+{
+  Field<int> neighbor_count_field{std::make_shared<EdgeNeighborCountFieldInput>()};
+  params.set_output("Face Count", std::move(neighbor_count_field));
+}
+
+}  // namespace blender::nodes::node_geo_input_mesh_edge_neighbors_cc
+
+void register_node_type_geo_input_mesh_edge_neighbors()
+{
+  namespace file_ns = blender::nodes::node_geo_input_mesh_edge_neighbors_cc;
+
+  static bNodeType ntype;
+  geo_node_type_base(
+      &ntype, GEO_NODE_INPUT_MESH_EDGE_NEIGHBORS, "Edge Neighbors", NODE_CLASS_INPUT, 0);
+  ntype.declare = file_ns::node_declare;
+  ntype.geometry_node_execute = file_ns::node_geo_exec;
+  nodeRegisterType(&ntype);
+}