Cleanup: move flip faces code from nodes to geometry module

source/blender/geometry/CMakeLists.txt

@@ -18,6 +18,7 @@ set(SRC
   intern/add_curves_on_mesh.cc
   intern/curve_constraints.cc
   intern/fillet_curves.cc
+  intern/mesh_flip_faces.cc
   intern/mesh_merge_by_distance.cc
   intern/mesh_primitive_cuboid.cc
   intern/mesh_split_edges.cc
@@ -37,6 +38,7 @@ set(SRC
   GEO_add_curves_on_mesh.hh
   GEO_curve_constraints.hh
   GEO_fillet_curves.hh
+  GEO_mesh_flip_faces.hh
   GEO_mesh_merge_by_distance.hh
   GEO_mesh_primitive_cuboid.hh
   GEO_mesh_split_edges.hh

source/blender/geometry/GEO_mesh_flip_faces.hh

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#pragma once
+
+#include "BLI_index_mask.hh"
+
+struct Mesh;
+
+namespace blender::geometry {
+
+/**
+ * Reverse the order of the vertices in the selected faces. This effectively changes the
+ * direction of the face normal.
+ */
+void flip_faces(Mesh &mesh, const IndexMask &selection);
+
+}  // namespace blender::geometry

source/blender/geometry/intern/mesh_flip_faces.cc

@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "GEO_mesh_flip_faces.hh"
+
+#include "DNA_mesh_types.h"
+
+#include "BLI_task.hh"
+
+#include "BKE_attribute.hh"
+#include "BKE_attribute_math.hh"
+#include "BKE_mesh.hh"
+
+namespace blender::geometry {
+
+void flip_faces(Mesh &mesh, const IndexMask &selection)
+{
+  if (mesh.totpoly == 0 || selection.is_empty()) {
+    return;
+  }
+
+  const Span<MPoly> polys = mesh.polys();
+  MutableSpan<int> corner_verts = mesh.corner_verts_for_write();
+  MutableSpan<int> corner_edges = mesh.corner_edges_for_write();
+
+  threading::parallel_for(selection.index_range(), 1024, [&](const IndexRange range) {
+    for (const int i : selection.slice(range)) {
+      const IndexRange poly(polys[i].loopstart, polys[i].totloop);
+      for (const int j : IndexRange(poly.size() / 2)) {
+        const int a = poly[j + 1];
+        const int b = poly.last(j);
+        std::swap(corner_verts[a], corner_verts[b]);
+        std::swap(corner_edges[a - 1], corner_edges[b]);
+      }
+    }
+  });
+
+  bke::MutableAttributeAccessor attributes = mesh.attributes_for_write();
+  attributes.for_all(
+      [&](const bke::AttributeIDRef &attribute_id, const bke::AttributeMetaData &meta_data) {
+        if (meta_data.data_type == CD_PROP_STRING) {
+          return true;
+        }
+        if (meta_data.domain != ATTR_DOMAIN_CORNER) {
+          return true;
+        }
+        if (ELEM(attribute_id.name(), ".corner_vert", ".corner_edge")) {
+          return true;
+        }
+        bke::GSpanAttributeWriter attribute = attributes.lookup_for_write_span(attribute_id);
+        attribute_math::convert_to_static_type(meta_data.data_type, [&](auto dummy) {
+          using T = decltype(dummy);
+          MutableSpan<T> dst_span = attribute.span.typed<T>();
+          threading::parallel_for(selection.index_range(), 1024, [&](const IndexRange range) {
+            for (const int i : selection.slice(range)) {
+              const IndexRange poly(polys[i].loopstart, polys[i].totloop);
+              dst_span.slice(poly.drop_front(1)).reverse();
+            }
+          });
+        });
+        attribute.finish();
+        return true;
+      });
+
+  BKE_mesh_tag_topology_changed(&mesh);
+}
+
+}  // namespace blender::geometry

source/blender/nodes/geometry/nodes/node_geo_flip_faces.cc

@@ -7,6 +7,8 @@
 
 #include "BKE_attribute_math.hh"
 
+#include "GEO_mesh_flip_faces.hh"
+
 #include "node_geometry_util.hh"
 
 namespace blender::nodes::node_geo_flip_faces_cc {
@@ -29,48 +31,7 @@ static void mesh_flip_faces(Mesh &mesh, const Field<bool> &selection_field)
   evaluator.evaluate();
   const IndexMask selection = evaluator.get_evaluated_as_mask(0);
 
-  const Span<MPoly> polys = mesh.polys();
-  MutableSpan<int> corner_verts = mesh.corner_verts_for_write();
-  MutableSpan<int> corner_edges = mesh.corner_edges_for_write();
-
-  threading::parallel_for(selection.index_range(), 1024, [&](const IndexRange range) {
-    for (const int i : selection.slice(range)) {
-      const IndexRange poly(polys[i].loopstart, polys[i].totloop);
-      for (const int j : IndexRange(poly.size() / 2)) {
-        const int a = poly[j + 1];
-        const int b = poly.last(j);
-        std::swap(corner_verts[a], corner_verts[b]);
-        std::swap(corner_edges[a - 1], corner_edges[b]);
-      }
-    }
-  });
-
-  MutableAttributeAccessor attributes = mesh.attributes_for_write();
-  attributes.for_all(
-      [&](const bke::AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
-        if (meta_data.data_type == CD_PROP_STRING) {
-          return true;
-        }
-        if (meta_data.domain != ATTR_DOMAIN_CORNER) {
-          return true;
-        }
-        if (ELEM(attribute_id.name(), ".corner_vert", ".corner_edge")) {
-          return true;
-        }
-        GSpanAttributeWriter attribute = attributes.lookup_for_write_span(attribute_id);
-        attribute_math::convert_to_static_type(meta_data.data_type, [&](auto dummy) {
-          using T = decltype(dummy);
-          MutableSpan<T> dst_span = attribute.span.typed<T>();
-          threading::parallel_for(selection.index_range(), 1024, [&](const IndexRange range) {
-            for (const int i : selection.slice(range)) {
-              const IndexRange poly(polys[i].loopstart, polys[i].totloop);
-              dst_span.slice(poly.drop_front(1)).reverse();
-            }
-          });
-        });
-        attribute.finish();
-        return true;
-      });
+  geometry::flip_faces(mesh, selection);
 }
 
 static void node_geo_exec(GeoNodeExecParams params)