geometry_component_curves.cc

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/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#include "BLI_task.hh"
 
#include "DNA_ID_enums.h"
#include "DNA_curve_types.h"
 
#include "BKE_attribute_math.hh"
#include "BKE_curves.hh"
#include "BKE_deform.hh"
#include "BKE_geometry_fields.hh"
#include "BKE_geometry_set.hh"
#include "BKE_lib_id.hh"
 
#include "FN_multi_function_builder.hh"
 
#include "attribute_access_intern.hh"
 
namespace blender::bke {
 
/* -------------------------------------------------------------------- */
CurveComponent::CurveComponent() : GeometryComponent(Type::Curve) {}
 
CurveComponent::CurveComponent(Curves *curve, GeometryOwnershipType ownership)
    : GeometryComponent(Type::Curve), curves_(curve), ownership_(ownership)
{
}
 
CurveComponent::~CurveComponent()
{
  this->clear();
}
 
GeometryComponentPtr CurveComponent::copy() const
{
  CurveComponent *new_component = new CurveComponent();
  if (curves_ != nullptr) {
    new_component->curves_ = BKE_curves_copy_for_eval(curves_);
    new_component->ownership_ = GeometryOwnershipType::Owned;
  }
  return GeometryComponentPtr(new_component);
}
 
void CurveComponent::clear()
{
  BLI_assert(this->is_mutable() || this->is_expired());
  if (curves_ != nullptr) {
    if (ownership_ == GeometryOwnershipType::Owned) {
      BKE_id_free(nullptr, curves_);
    }
    if (curve_for_render_ != nullptr) {
      /* The curve created by this component should not have any edit mode data. */
      BLI_assert(curve_for_render_->editfont == nullptr && curve_for_render_->editnurb == nullptr);
      BKE_id_free(nullptr, curve_for_render_);
      curve_for_render_ = nullptr;
    }
 
    curves_ = nullptr;
  }
}
 
bool CurveComponent::has_curves() const
{
  return curves_ != nullptr;
}
 
void CurveComponent::replace(Curves *curves, GeometryOwnershipType ownership)
{
  BLI_assert(this->is_mutable());
  this->clear();
  curves_ = curves;
  ownership_ = ownership;
}
 
Curves *CurveComponent::release()
{
  BLI_assert(this->is_mutable());
  Curves *curves = curves_;
  curves_ = nullptr;
  return curves;
}
 
const Curves *CurveComponent::get() const
{
  return curves_;
}
 
Curves *CurveComponent::get_for_write()
{
  BLI_assert(this->is_mutable());
  if (ownership_ == GeometryOwnershipType::ReadOnly) {
    curves_ = BKE_curves_copy_for_eval(curves_);
    ownership_ = GeometryOwnershipType::Owned;
  }
  return curves_;
}
 
bool CurveComponent::is_empty() const
{
  return curves_ == nullptr;
}
 
bool CurveComponent::owns_direct_data() const
{
  return ownership_ == GeometryOwnershipType::Owned;
}
 
void CurveComponent::ensure_owns_direct_data()
{
  BLI_assert(this->is_mutable());
  if (ownership_ != GeometryOwnershipType::Owned) {
    if (curves_) {
      curves_ = BKE_curves_copy_for_eval(curves_);
    }
    ownership_ = GeometryOwnershipType::Owned;
  }
}
 
void CurveComponent::count_memory(MemoryCounter &memory) const
{
  if (curves_) {
    curves_->geometry.wrap().count_memory(memory);
  }
}
 
const Curve *CurveComponent::get_curve_for_render() const
{
  if (curves_ == nullptr) {
    return nullptr;
  }
  if (curve_for_render_ != nullptr) {
    return curve_for_render_;
  }
  std::lock_guard lock{curve_for_render_mutex_};
  if (curve_for_render_ != nullptr) {
    return curve_for_render_;
  }
 
  curve_for_render_ = (Curve *)BKE_id_new_nomain(ID_CU_LEGACY, nullptr);
  curve_for_render_->curve_eval = curves_;
 
  return curve_for_render_;
}
 
/* -------------------------------------------------------------------- */
static Array<float3> curve_normal_point_domain(const CurvesGeometry &curves)
{
  const OffsetIndices points_by_curve = curves.points_by_curve();
  const OffsetIndices evaluated_points_by_curve = curves.evaluated_points_by_curve();
  const VArray<int8_t> types = curves.curve_types();
  const VArray<int> resolutions = curves.resolution();
  const VArray<bool> curves_cyclic = curves.cyclic();
  const AttributeAccessor attributes = curves.attributes();
  const VArray<float3> custom_normals = *attributes.lookup_or_default<float3>(
      "custom_normal", AttrDomain::Point, float3(0, 0, 1));
 
  const Span<float3> positions = curves.positions();
  const VArray<int8_t> normal_modes = curves.normal_mode();
 
  const Span<float3> evaluated_normals = curves.evaluated_normals();
 
  Array<float3> results(curves.points_num());
 
  threading::parallel_for(curves.curves_range(), 128, [&](IndexRange range) {
    Vector<float3> nurbs_tangents;
 
    for (const int i_curve : range) {
      const IndexRange points = points_by_curve[i_curve];
      const IndexRange evaluated_points = evaluated_points_by_curve[i_curve];
 
      MutableSpan<float3> curve_normals = results.as_mutable_span().slice(points);
 
      switch (types[i_curve]) {
        case CURVE_TYPE_CATMULL_ROM: {
          const Span<float3> normals = evaluated_normals.slice(evaluated_points);
          const int resolution = resolutions[i_curve];
          for (const int i : IndexRange(points.size())) {
            curve_normals[i] = normals[resolution * i];
          }
          break;
        }
        case CURVE_TYPE_POLY:
          curve_normals.copy_from(evaluated_normals.slice(evaluated_points));
          break;
        case CURVE_TYPE_BEZIER: {
          const Span<float3> normals = evaluated_normals.slice(evaluated_points);
          curve_normals.first() = normals.first();
          const Span<int> offsets = curves.bezier_evaluated_offsets_for_curve(i_curve);
          for (const int i : IndexRange(points.size()).drop_front(1)) {
            curve_normals[i] = normals[offsets[i]];
          }
          break;
        }
        case CURVE_TYPE_NURBS: {
          /* For NURBS curves there is no obvious correspondence between specific evaluated points
           * and control points, so normals are determined by treating them as poly curves. */
          nurbs_tangents.clear();
          nurbs_tangents.resize(points.size());
          const bool cyclic = curves_cyclic[i_curve];
          const Span<float3> curve_positions = positions.slice(points);
          curves::poly::calculate_tangents(curve_positions, cyclic, nurbs_tangents);
          switch (NormalMode(normal_modes[i_curve])) {
            case NORMAL_MODE_Z_UP:
              curves::poly::calculate_normals_z_up(nurbs_tangents, curve_normals);
              break;
            case NORMAL_MODE_MINIMUM_TWIST:
              curves::poly::calculate_normals_minimum(nurbs_tangents, cyclic, curve_normals);
              break;
            case NORMAL_MODE_FREE:
              custom_normals.materialize(points, curve_normals);
              break;
          }
          break;
        }
      }
    }
  });
  return results;
}
 
VArray<float3> curve_normals_varray(const CurvesGeometry &curves, const AttrDomain domain)
{
  const VArray<int8_t> types = curves.curve_types();
  if (curves.is_single_type(CURVE_TYPE_POLY)) {
    return curves.adapt_domain<float3>(
        VArray<float3>::ForSpan(curves.evaluated_normals()), AttrDomain::Point, domain);
  }
 
  Array<float3> normals = curve_normal_point_domain(curves);
 
  if (domain == AttrDomain::Point) {
    return VArray<float3>::ForContainer(std::move(normals));
  }
 
  if (domain == AttrDomain::Curve) {
    return curves.adapt_domain<float3>(
        VArray<float3>::ForContainer(std::move(normals)), AttrDomain::Point, AttrDomain::Curve);
  }
 
  return nullptr;
}
 
/* -------------------------------------------------------------------- */
static VArray<float> construct_curve_length_gvarray(const CurvesGeometry &curves,
                                                    const AttrDomain domain)
{
  curves.ensure_evaluated_lengths();
 
  VArray<bool> cyclic = curves.cyclic();
  VArray<float> lengths = VArray<float>::ForFunc(
      curves.curves_num(), [&curves, cyclic = std::move(cyclic)](int64_t index) {
        return curves.evaluated_length_total_for_curve(index, cyclic[index]);
      });
 
  if (domain == AttrDomain::Curve) {
    return lengths;
  }
 
  if (domain == AttrDomain::Point) {
    return curves.adapt_domain<float>(std::move(lengths), AttrDomain::Curve, AttrDomain::Point);
  }
 
  return {};
}
 
CurveLengthFieldInput::CurveLengthFieldInput()
    : CurvesFieldInput(CPPType::get<float>(), "Spline Length node")
{
  category_ = Category::Generated;
}
 
GVArray CurveLengthFieldInput::get_varray_for_context(const CurvesGeometry &curves,
                                                      const AttrDomain domain,
                                                      const IndexMask & /*mask*/) const
{
  return construct_curve_length_gvarray(curves, domain);
}
 
uint64_t CurveLengthFieldInput::hash() const
{
  /* Some random constant hash. */
  return 3549623580;
}
 
bool CurveLengthFieldInput::is_equal_to(const fn::FieldNode &other) const
{
  return dynamic_cast<const CurveLengthFieldInput *>(&other) != nullptr;
}
 
std::optional<AttrDomain> CurveLengthFieldInput::preferred_domain(
    const CurvesGeometry & /*curves*/) const
{
  return AttrDomain::Curve;
}
 
/* -------------------------------------------------------------------- */
static void tag_component_topology_changed(void *owner)
{
  CurvesGeometry &curves = *static_cast<CurvesGeometry *>(owner);
  curves.tag_topology_changed();
}
 
static void tag_component_curve_types_changed(void *owner)
{
  CurvesGeometry &curves = *static_cast<CurvesGeometry *>(owner);
  curves.update_curve_types();
  curves.tag_topology_changed();
}
 
static void tag_component_positions_changed(void *owner)
{
  CurvesGeometry &curves = *static_cast<CurvesGeometry *>(owner);
  curves.tag_positions_changed();
}
 
static void tag_component_radii_changed(void *owner)
{
  CurvesGeometry &curves = *static_cast<CurvesGeometry *>(owner);
  curves.tag_radii_changed();
}
 
static void tag_component_normals_changed(void *owner)
{
  CurvesGeometry &curves = *static_cast<CurvesGeometry *>(owner);
  curves.tag_normals_changed();
}
 
/* -------------------------------------------------------------------- */
class CurvesVertexGroupsAttributeProvider final : public DynamicAttributesProvider {
 public:
  GAttributeReader try_get_for_read(const void *owner, const StringRef attribute_id) const final
  {
    if (bke::attribute_name_is_anonymous(attribute_id)) {
      return {};
    }
    const CurvesGeometry *curves = static_cast<const CurvesGeometry *>(owner);
    if (curves == nullptr) {
      return {};
    }
    const int vertex_group_index = BKE_defgroup_name_index(&curves->vertex_group_names,
                                                           attribute_id);
    if (vertex_group_index < 0) {
      return {};
    }
    const Span<MDeformVert> dverts = curves->deform_verts();
    return this->get_for_vertex_group_index(*curves, dverts, vertex_group_index);
  }
 
  GAttributeReader get_for_vertex_group_index(const CurvesGeometry &curves,
                                              const Span<MDeformVert> dverts,
                                              const int vertex_group_index) const
  {
    BLI_assert(vertex_group_index >= 0);
    if (dverts.is_empty()) {
      return {VArray<float>::ForSingle(0.0f, curves.points_num()), AttrDomain::Point};
    }
    return {varray_for_deform_verts(dverts, vertex_group_index), AttrDomain::Point};
  }
 
  GAttributeWriter try_get_for_write(void *owner, const StringRef attribute_id) const final
  {
    if (bke::attribute_name_is_anonymous(attribute_id)) {
      return {};
    }
    CurvesGeometry *curves = static_cast<CurvesGeometry *>(owner);
    if (curves == nullptr) {
      return {};
    }
    const int vertex_group_index = BKE_defgroup_name_index(&curves->vertex_group_names,
                                                           attribute_id);
    if (vertex_group_index < 0) {
      return {};
    }
    MutableSpan<MDeformVert> dverts = curves->deform_verts_for_write();
    return {varray_for_mutable_deform_verts(dverts, vertex_group_index), AttrDomain::Point};
  }
 
  bool try_delete(void *owner, const StringRef attribute_id) const final
  {
    if (bke::attribute_name_is_anonymous(attribute_id)) {
      return false;
    }
    CurvesGeometry *curves = static_cast<CurvesGeometry *>(owner);
    if (curves == nullptr) {
      return true;
    }
    const std::string name = attribute_id;
 
    int index;
    bDeformGroup *group;
    if (!BKE_defgroup_listbase_name_find(
            &curves->vertex_group_names, name.c_str(), &index, &group))
    {
      return false;
    }
    BLI_remlink(&curves->vertex_group_names, group);
    MEM_freeN(group);
    if (curves->deform_verts().is_empty()) {
      return true;
    }
 
    MutableSpan<MDeformVert> dverts = curves->deform_verts_for_write();
    remove_defgroup_index(dverts, index);
    return true;
  }
 
  bool foreach_attribute(const void *owner,
                         FunctionRef<void(const AttributeIter &)> fn) const final
  {
    const CurvesGeometry *curves = static_cast<const CurvesGeometry *>(owner);
    if (curves == nullptr) {
      return true;
    }
    const Span<MDeformVert> dverts = curves->deform_verts();
 
    int group_index = 0;
    LISTBASE_FOREACH_INDEX (const bDeformGroup *, group, &curves->vertex_group_names, group_index)
    {
      const auto get_fn = [&]() {
        return this->get_for_vertex_group_index(*curves, dverts, group_index);
      };
      AttributeIter iter{group->name, AttrDomain::Point, CD_PROP_FLOAT, get_fn};
      fn(iter);
      if (iter.is_stopped()) {
        return false;
      }
    }
    return true;
  }
 
  void foreach_domain(const FunctionRef<void(AttrDomain)> callback) const final
  {
    callback(AttrDomain::Point);
  }
};
 
static ComponentAttributeProviders create_attribute_providers_for_curve()
{
  static CustomDataAccessInfo curve_access = {
      [](void *owner) -> CustomData * {
        CurvesGeometry &curves = *static_cast<CurvesGeometry *>(owner);
        return &curves.curve_data;
      },
      [](const void *owner) -> const CustomData * {
        const CurvesGeometry &curves = *static_cast<const CurvesGeometry *>(owner);
        return &curves.curve_data;
      },
      [](const void *owner) -> int {
        const CurvesGeometry &curves = *static_cast<const CurvesGeometry *>(owner);
        return curves.curves_num();
      }};
  static CustomDataAccessInfo point_access = {
      [](void *owner) -> CustomData * {
        CurvesGeometry &curves = *static_cast<CurvesGeometry *>(owner);
        return &curves.point_data;
      },
      [](const void *owner) -> const CustomData * {
        const CurvesGeometry &curves = *static_cast<const CurvesGeometry *>(owner);
        return &curves.point_data;
      },
      [](const void *owner) -> int {
        const CurvesGeometry &curves = *static_cast<const CurvesGeometry *>(owner);
        return curves.points_num();
      }};
 
  static BuiltinCustomDataLayerProvider position("position",
                                                 AttrDomain::Point,
                                                 CD_PROP_FLOAT3,
                                                 BuiltinAttributeProvider::NonDeletable,
                                                 point_access,
                                                 tag_component_positions_changed);
 
  static BuiltinCustomDataLayerProvider radius("radius",
                                               AttrDomain::Point,
                                               CD_PROP_FLOAT,
                                               BuiltinAttributeProvider::Deletable,
                                               point_access,
                                               tag_component_radii_changed);
 
  static BuiltinCustomDataLayerProvider id("id",
                                           AttrDomain::Point,
                                           CD_PROP_INT32,
                                           BuiltinAttributeProvider::Deletable,
                                           point_access,
                                           nullptr);
 
  static BuiltinCustomDataLayerProvider tilt("tilt",
                                             AttrDomain::Point,
                                             CD_PROP_FLOAT,
                                             BuiltinAttributeProvider::Deletable,
                                             point_access,
                                             tag_component_normals_changed);
 
  static BuiltinCustomDataLayerProvider handle_right("handle_right",
                                                     AttrDomain::Point,
                                                     CD_PROP_FLOAT3,
                                                     BuiltinAttributeProvider::Deletable,
                                                     point_access,
                                                     tag_component_positions_changed);
 
  static BuiltinCustomDataLayerProvider handle_left("handle_left",
                                                    AttrDomain::Point,
                                                    CD_PROP_FLOAT3,
                                                    BuiltinAttributeProvider::Deletable,
                                                    point_access,
                                                    tag_component_positions_changed);
 
  static auto handle_type_clamp = mf::build::SI1_SO<int8_t, int8_t>(
      "Handle Type Validate",
      [](int8_t value) {
        return std::clamp<int8_t>(value, BEZIER_HANDLE_FREE, BEZIER_HANDLE_ALIGN);
      },
      mf::build::exec_presets::AllSpanOrSingle());
  static BuiltinCustomDataLayerProvider handle_type_right("handle_type_right",
                                                          AttrDomain::Point,
                                                          CD_PROP_INT8,
                                                          BuiltinAttributeProvider::Deletable,
                                                          point_access,
                                                          tag_component_topology_changed,
                                                          AttributeValidator{&handle_type_clamp});
 
  static BuiltinCustomDataLayerProvider handle_type_left("handle_type_left",
                                                         AttrDomain::Point,
                                                         CD_PROP_INT8,
                                                         BuiltinAttributeProvider::Deletable,
                                                         point_access,
                                                         tag_component_topology_changed,
                                                         AttributeValidator{&handle_type_clamp});
 
  static BuiltinCustomDataLayerProvider nurbs_weight("nurbs_weight",
                                                     AttrDomain::Point,
                                                     CD_PROP_FLOAT,
                                                     BuiltinAttributeProvider::Deletable,
                                                     point_access,
                                                     tag_component_positions_changed);
 
  static const auto nurbs_order_clamp = mf::build::SI1_SO<int8_t, int8_t>(
      "NURBS Order Validate",
      [](int8_t value) { return std::max<int8_t>(value, 1); },
      mf::build::exec_presets::AllSpanOrSingle());
  static int nurbs_order_default = 4;
  static BuiltinCustomDataLayerProvider nurbs_order("nurbs_order",
                                                    AttrDomain::Curve,
                                                    CD_PROP_INT8,
                                                    BuiltinAttributeProvider::Deletable,
                                                    curve_access,
                                                    tag_component_topology_changed,
                                                    AttributeValidator{&nurbs_order_clamp},
                                                    &nurbs_order_default);
 
  static const auto normal_mode_clamp = mf::build::SI1_SO<int8_t, int8_t>(
      "Normal Mode Validate",
      [](int8_t value) {
        return std::clamp<int8_t>(value, NORMAL_MODE_MINIMUM_TWIST, NORMAL_MODE_FREE);
      },
      mf::build::exec_presets::AllSpanOrSingle());
  static BuiltinCustomDataLayerProvider normal_mode("normal_mode",
                                                    AttrDomain::Curve,
                                                    CD_PROP_INT8,
                                                    BuiltinAttributeProvider::Deletable,
                                                    curve_access,
                                                    tag_component_normals_changed,
                                                    AttributeValidator{&normal_mode_clamp});
 
  static BuiltinCustomDataLayerProvider custom_normal("custom_normal",
                                                      AttrDomain::Point,
                                                      CD_PROP_FLOAT3,
                                                      BuiltinAttributeProvider::Deletable,
                                                      point_access,
                                                      tag_component_normals_changed);
 
  static const auto knots_mode_clamp = mf::build::SI1_SO<int8_t, int8_t>(
      "Knots Mode Validate",
      [](int8_t value) {
        return std::clamp<int8_t>(value, NURBS_KNOT_MODE_NORMAL, NURBS_KNOT_MODE_ENDPOINT_BEZIER);
      },
      mf::build::exec_presets::AllSpanOrSingle());
  static BuiltinCustomDataLayerProvider nurbs_knots_mode("knots_mode",
                                                         AttrDomain::Curve,
                                                         CD_PROP_INT8,
                                                         BuiltinAttributeProvider::Deletable,
                                                         curve_access,
                                                         tag_component_topology_changed,
                                                         AttributeValidator{&knots_mode_clamp});
 
  static const auto curve_type_clamp = mf::build::SI1_SO<int8_t, int8_t>(
      "Curve Type Validate",
      [](int8_t value) {
        return std::clamp<int8_t>(value, CURVE_TYPE_CATMULL_ROM, CURVE_TYPES_NUM);
      },
      mf::build::exec_presets::AllSpanOrSingle());
  static BuiltinCustomDataLayerProvider curve_type("curve_type",
                                                   AttrDomain::Curve,
                                                   CD_PROP_INT8,
                                                   BuiltinAttributeProvider::Deletable,
                                                   curve_access,
                                                   tag_component_curve_types_changed,
                                                   AttributeValidator{&curve_type_clamp});
 
  static const auto resolution_clamp = mf::build::SI1_SO<int, int>(
      "Resolution Validate",
      [](int value) { return std::max<int>(value, 1); },
      mf::build::exec_presets::AllSpanOrSingle());
  static int resolution_default = 12;
  static BuiltinCustomDataLayerProvider resolution("resolution",
                                                   AttrDomain::Curve,
                                                   CD_PROP_INT32,
                                                   BuiltinAttributeProvider::Deletable,
                                                   curve_access,
                                                   tag_component_topology_changed,
                                                   AttributeValidator{&resolution_clamp},
                                                   &resolution_default);
 
  static BuiltinCustomDataLayerProvider cyclic("cyclic",
                                               AttrDomain::Curve,
                                               CD_PROP_BOOL,
                                               BuiltinAttributeProvider::Deletable,
                                               curve_access,
                                               tag_component_topology_changed);
 
  static CurvesVertexGroupsAttributeProvider vertex_groups;
  static CustomDataAttributeProvider curve_custom_data(AttrDomain::Curve, curve_access);
  static CustomDataAttributeProvider point_custom_data(AttrDomain::Point, point_access);
 
  return ComponentAttributeProviders({&position,
                                      &radius,
                                      &id,
                                      &tilt,
                                      &handle_right,
                                      &handle_left,
                                      &handle_type_right,
                                      &handle_type_left,
                                      &normal_mode,
                                      &custom_normal,
                                      &nurbs_order,
                                      &nurbs_knots_mode,
                                      &nurbs_weight,
                                      &curve_type,
                                      &resolution,
                                      &cyclic},
                                     {&vertex_groups, &curve_custom_data, &point_custom_data});
}
 
static AttributeAccessorFunctions get_curves_accessor_functions()
{
  static const ComponentAttributeProviders providers = create_attribute_providers_for_curve();
  AttributeAccessorFunctions fn =
      attribute_accessor_functions::accessor_functions_for_providers<providers>();
  fn.domain_size = [](const void *owner, const AttrDomain domain) {
    if (owner == nullptr) {
      return 0;
    }
    const CurvesGeometry &curves = *static_cast<const CurvesGeometry *>(owner);
    switch (domain) {
      case AttrDomain::Point:
        return curves.points_num();
      case AttrDomain::Curve:
        return curves.curves_num();
      default:
        return 0;
    }
  };
  fn.domain_supported = [](const void * /*owner*/, const AttrDomain domain) {
    return ELEM(domain, AttrDomain::Point, AttrDomain::Curve);
  };
  fn.adapt_domain = [](const void *owner,
                       const GVArray &varray,
                       const AttrDomain from_domain,
                       const AttrDomain to_domain) -> GVArray {
    if (owner == nullptr) {
      return {};
    }
    const CurvesGeometry &curves = *static_cast<const CurvesGeometry *>(owner);
    return curves.adapt_domain(varray, from_domain, to_domain);
  };
  return fn;
}
 
static const AttributeAccessorFunctions &get_curves_accessor_functions_ref()
{
  static const AttributeAccessorFunctions fn = get_curves_accessor_functions();
  return fn;
}
 
AttributeAccessor CurvesGeometry::attributes() const
{
  return AttributeAccessor(this, get_curves_accessor_functions_ref());
}
 
MutableAttributeAccessor CurvesGeometry::attributes_for_write()
{
  return MutableAttributeAccessor(this, get_curves_accessor_functions_ref());
}
 
std::optional<AttributeAccessor> CurveComponent::attributes() const
{
  return AttributeAccessor(curves_ ? &curves_->geometry : nullptr,
                           get_curves_accessor_functions_ref());
}
 
std::optional<MutableAttributeAccessor> CurveComponent::attributes_for_write()
{
  Curves *curves = this->get_for_write();
  return MutableAttributeAccessor(curves ? &curves->geometry : nullptr,
                                  get_curves_accessor_functions_ref());
}
 
}  // namespace blender::bke