Geometry Nodes: Add index input to Edge Vertices node

Previously the edge index was always determined by the field context,
and the node didn't work when the context was in any other domain.
Adding an index input makes it work much more nicely with the other
topology nodes. It's now in the topology submenu too.

I also reimplemented the edge positions input to use the field at index
node internally. That will probably make it slower for now, but we need
to optimize that to do nothing in some special cases anyway.

Differential Revision: https://developer.blender.org/D16105

1 files changed, 46 insertions, 84 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_input_mesh_edge_vertices.cc b/source/blender/nodes/geometry/nodes/node_geo_input_mesh_edge_vertices.cc
index b345ea68cd1..31c82133e2f 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_input_mesh_edge_vertices.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_input_mesh_edge_vertices.cc
@@ -11,35 +11,33 @@ namespace blender::nodes::node_geo_input_mesh_edge_vertices_cc {
 
 static void node_declare(NodeDeclarationBuilder &b)
 {
+  b.add_input<decl::Int>(N_("Edge Index"))
+      .implicit_field(implicit_field_inputs::index)
+      .description(N_("The edge to retrieve data from. Defaults to the edge from the context"));
   b.add_output<decl::Int>(N_("Vertex Index 1"))
-      .field_source()
+      .dependent_field()
       .description(N_("The index of the first vertex in the edge"));
   b.add_output<decl::Int>(N_("Vertex Index 2"))
-      .field_source()
+      .dependent_field()
       .description(N_("The index of the second vertex in the edge"));
   b.add_output<decl::Vector>(N_("Position 1"))
-      .field_source()
+      .dependent_field()
       .description(N_("The position of the first vertex in the edge"));
   b.add_output<decl::Vector>(N_("Position 2"))
-      .field_source()
+      .dependent_field()
       .description(N_("The position of the second vertex in the edge"));
 }
 
 enum class VertNumber { V1, V2 };
 
-static VArray<int> construct_edge_verts_gvarray(const Mesh &mesh,
-                                                const VertNumber vertex,
-                                                const eAttrDomain domain)
+static int edge_get_v1(const MEdge &edge)
 {
-  const Span<MEdge> edges = mesh.edges();
-  if (domain == ATTR_DOMAIN_EDGE) {
-    if (vertex == VertNumber::V1) {
-      return VArray<int>::ForFunc(edges.size(),
-                                  [edges](const int i) -> int { return edges[i].v1; });
-    }
-    return VArray<int>::ForFunc(edges.size(), [edges](const int i) -> int { return edges[i].v2; });
-  }
-  return {};
+  return edge.v1;
+}
+
+static int edge_get_v2(const MEdge &edge)
+{
+  return edge.v2;
 }
 
 class EdgeVertsInput final : public bke::MeshFieldInput {
@@ -57,7 +55,17 @@ class EdgeVertsInput final : public bke::MeshFieldInput {
                                  const eAttrDomain domain,
                                  IndexMask UNUSED(mask)) const final
   {
-    return construct_edge_verts_gvarray(mesh, vertex_, domain);
+    if (domain != ATTR_DOMAIN_EDGE) {
+      return {};
+    }
+    switch (vertex_) {
+      case VertNumber::V1:
+        return VArray<int>::ForDerivedSpan<MEdge, edge_get_v1>(mesh.edges());
+      case VertNumber::V2:
+        return VArray<int>::ForDerivedSpan<MEdge, edge_get_v2>(mesh.edges());
+    }
+    BLI_assert_unreachable();
+    return {};
   }
 
   uint64_t hash() const override
@@ -79,76 +87,30 @@ class EdgeVertsInput final : public bke::MeshFieldInput {
   }
 };
 
-static VArray<float3> construct_edge_positions_gvarray(const Mesh &mesh,
-                                                       const VertNumber vertex,
-                                                       const eAttrDomain domain)
+static void node_geo_exec(GeoNodeExecParams params)
 {
-  const Span<MVert> verts = mesh.verts();
-  const Span<MEdge> edges = mesh.edges();
-
-  if (vertex == VertNumber::V1) {
-    return mesh.attributes().adapt_domain<float3>(
-        VArray<float3>::ForFunc(edges.size(),
-                                [verts, edges](const int i) { return verts[edges[i].v1].co; }),
-        ATTR_DOMAIN_EDGE,
-        domain);
-  }
-  return mesh.attributes().adapt_domain<float3>(
-      VArray<float3>::ForFunc(edges.size(),
-                              [verts, edges](const int i) { return verts[edges[i].v2].co; }),
-      ATTR_DOMAIN_EDGE,
-      domain);
-}
-
-class EdgePositionFieldInput final : public bke::MeshFieldInput {
- private:
-  VertNumber vertex_;
-
- public:
-  EdgePositionFieldInput(VertNumber vertex)
-      : bke::MeshFieldInput(CPPType::get<float3>(), "Edge Position Field"), vertex_(vertex)
-  {
-    category_ = Category::Generated;
-  }
-
-  GVArray get_varray_for_context(const Mesh &mesh,
-                                 const eAttrDomain domain,
-                                 IndexMask UNUSED(mask)) const final
-  {
-    return construct_edge_positions_gvarray(mesh, vertex_, domain);
+  const Field<int> edge_index = params.extract_input<Field<int>>("Edge Index");
+  Field<int> vertex_field_1(std::make_shared<FieldAtIndexInput>(
+      edge_index, Field<int>(std::make_shared<EdgeVertsInput>(VertNumber::V1)), ATTR_DOMAIN_EDGE));
+  Field<int> vertex_field_2(std::make_shared<FieldAtIndexInput>(
+      edge_index, Field<int>(std::make_shared<EdgeVertsInput>(VertNumber::V2)), ATTR_DOMAIN_EDGE));
+
+  params.set_output("Vertex Index 1", vertex_field_1);
+  params.set_output("Vertex Index 2", vertex_field_2);
+  if (params.output_is_required("Position 1")) {
+    params.set_output("Position 1",
+                      Field<float3>(std::make_shared<FieldAtIndexInput>(
+                          vertex_field_1,
+                          Field<float3>(AttributeFieldInput::Create<float3>("position")),
+                          ATTR_DOMAIN_POINT)));
   }
-
-  uint64_t hash() const override
-  {
-    return vertex_ == VertNumber::V1 ? 987456978362 : 374587679866;
+  if (params.output_is_required("Position 2")) {
+    params.set_output("Position 2",
+                      Field<float3>(std::make_shared<FieldAtIndexInput>(
+                          vertex_field_2,
+                          Field<float3>(AttributeFieldInput::Create<float3>("position")),
+                          ATTR_DOMAIN_POINT)));
   }
-
-  bool is_equal_to(const fn::FieldNode &other) const override
-  {
-    if (const EdgePositionFieldInput *other_field = dynamic_cast<const EdgePositionFieldInput *>(
-            &other)) {
-      return vertex_ == other_field->vertex_;
-    }
-    return false;
-  }
-
-  std::optional<eAttrDomain> preferred_domain(const Mesh & /*mesh*/) const override
-  {
-    return ATTR_DOMAIN_EDGE;
-  }
-};
-
-static void node_geo_exec(GeoNodeExecParams params)
-{
-  Field<int> vertex_field_1{std::make_shared<EdgeVertsInput>(VertNumber::V1)};
-  Field<int> vertex_field_2{std::make_shared<EdgeVertsInput>(VertNumber::V2)};
-  Field<float3> position_field_1{std::make_shared<EdgePositionFieldInput>(VertNumber::V1)};
-  Field<float3> position_field_2{std::make_shared<EdgePositionFieldInput>(VertNumber::V2)};
-
-  params.set_output("Vertex Index 1", std::move(vertex_field_1));
-  params.set_output("Vertex Index 2", std::move(vertex_field_2));
-  params.set_output("Position 1", std::move(position_field_1));
-  params.set_output("Position 2", std::move(position_field_2));
 }
 
 }  // namespace blender::nodes::node_geo_input_mesh_edge_vertices_cc