1 files changed, 110 insertions, 0 deletions
diff --git a/source/blender/nodes/geometry/nodes/node_geo_edge_paths_to_curves.cc b/source/blender/nodes/geometry/nodes/node_geo_edge_paths_to_curves.cc
new file mode 100644
index 00000000000..ba09acf0bf0
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_edge_paths_to_curves.cc
@@ -0,0 +1,110 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "BKE_curves.hh"
+
+#include "DNA_mesh_types.h"
+
+#include "GEO_mesh_to_curve.hh"
+
+#include "node_geometry_util.hh"
+
+namespace blender::nodes::node_geo_edge_paths_to_curves_cc {
+
+static void node_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Geometry>(N_("Mesh")).supported_type(GEO_COMPONENT_TYPE_MESH);
+  b.add_input<decl::Bool>(N_("Start Vertices")).default_value(true).hide_value().supports_field();
+  b.add_input<decl::Int>(N_("Next Vertex Index")).default_value(-1).hide_value().supports_field();
+  b.add_output<decl::Geometry>(N_("Curves"));
+}
+
+static Curves *edge_paths_to_curves_convert(const Mesh &mesh,
+                                            const IndexMask start_verts_mask,
+                                            const Span<int> next_indices)
+{
+  Vector<int> vert_indices;
+  Vector<int> curve_offsets;
+  Array<bool> visited(mesh.totvert, false);
+  for (const int first_vert : start_verts_mask) {
+    const int second_vert = next_indices[first_vert];
+    if (first_vert == second_vert) {
+      continue;
+    }
+    if (second_vert < 0 || second_vert >= mesh.totvert) {
+      continue;
+    }
+
+    curve_offsets.append(vert_indices.size());
+
+    /* Iterate through path defined by #next_indices. */
+    int current_vert = first_vert;
+    while (!visited[current_vert]) {
+      visited[current_vert] = true;
+      vert_indices.append(current_vert);
+      const int next_vert = next_indices[current_vert];
+      if (next_vert < 0 || next_vert >= mesh.totvert) {
+        break;
+      }
+      current_vert = next_vert;
+    }
+
+    /* Reset visited status. */
+    const int points_in_curve_num = vert_indices.size() - curve_offsets.last();
+    for (const int vert_in_curve : vert_indices.as_span().take_back(points_in_curve_num)) {
+      visited[vert_in_curve] = false;
+    }
+  }
+
+  if (vert_indices.is_empty()) {
+    return nullptr;
+  }
+  Curves *curves_id = bke::curves_new_nomain(
+      geometry::create_curve_from_vert_indices(mesh, vert_indices, curve_offsets, IndexRange(0)));
+  return curves_id;
+}
+
+static void node_geo_exec(GeoNodeExecParams params)
+{
+  GeometrySet geometry_set = params.extract_input<GeometrySet>("Mesh");
+
+  geometry_set.modify_geometry_sets([&](GeometrySet &geometry_set) {
+    const Mesh *mesh = geometry_set.get_mesh_for_read();
+    if (mesh == nullptr) {
+      geometry_set.keep_only({GEO_COMPONENT_TYPE_INSTANCES});
+      return;
+    }
+
+    bke::MeshFieldContext context{*mesh, ATTR_DOMAIN_POINT};
+    fn::FieldEvaluator evaluator{context, mesh->totvert};
+    evaluator.add(params.get_input<Field<int>>("Next Vertex Index"));
+    evaluator.add(params.get_input<Field<bool>>("Start Vertices"));
+    evaluator.evaluate();
+    const VArraySpan<int> next_vert = evaluator.get_evaluated<int>(0);
+    IndexMask start_verts = evaluator.get_evaluated_as_mask(1);
+
+    if (start_verts.is_empty()) {
+      geometry_set.keep_only({GEO_COMPONENT_TYPE_INSTANCES});
+      return;
+    }
+
+    geometry_set.replace_curves(edge_paths_to_curves_convert(*mesh, start_verts, next_vert));
+    geometry_set.keep_only({GEO_COMPONENT_TYPE_CURVE, GEO_COMPONENT_TYPE_INSTANCES});
+  });
+
+  params.set_output("Curves", std::move(geometry_set));
+}
+
+}  // namespace blender::nodes::node_geo_edge_paths_to_curves_cc
+
+void register_node_type_geo_edge_paths_to_curves()
+{
+  namespace file_ns = blender::nodes::node_geo_edge_paths_to_curves_cc;
+
+  static bNodeType ntype;
+
+  geo_node_type_base(
+      &ntype, GEO_NODE_EDGE_PATHS_TO_CURVES, "Edge Paths to Curves", NODE_CLASS_GEOMETRY);
+  ntype.declare = file_ns::node_declare;
+  ntype.geometry_node_execute = file_ns::node_geo_exec;
+  nodeRegisterType(&ntype);
+}