resample_curves.cc

Go to the documentation of this file.

/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#include "BLI_array_utils.hh"
#include "BLI_math_color.hh"
#include "BLI_math_quaternion.hh"
#include "BLI_math_vector.hh"
 
#include "BLI_length_parameterize.hh"
#include "BLI_task.hh"
 
#include "FN_field.hh"
#include "FN_multi_function_builder.hh"
 
#include "BKE_attribute_math.hh"
#include "BKE_curves.hh"
#include "BKE_curves_utils.hh"
#include "BKE_deform.hh"
#include "BKE_geometry_fields.hh"
 
#include "GEO_resample_curves.hh"
 
namespace blender::geometry {
 
static fn::Field<int> get_count_input_max_one(const fn::Field<int> &count_field)
{
  static auto max_one_fn = mf::build::SI1_SO<int, int>(
      "Clamp Above One",
      [](int value) { return std::max(1, value); },
      mf::build::exec_presets::AllSpanOrSingle());
  return fn::Field<int>(fn::FieldOperation::from(max_one_fn, {count_field}));
}
 
static int get_count_from_length(const float curve_length,
                                 const float sample_length,
                                 const bool keep_last_segment)
{
  /* Find the number of sampled segments by dividing the total length by
   * the sample length. Then there is one more sampled point than segment. */
  if (UNLIKELY(sample_length == 0.0f)) {
    return 1;
  }
  const int count = int(curve_length / sample_length) + 1;
  return std::max(keep_last_segment ? 2 : 1, count);
}
 
static fn::Field<int> get_count_input_from_length(const fn::Field<float> &length_field,
                                                  const bool keep_last_segment)
{
  static auto get_count_fn = mf::build::SI3_SO<float, float, bool, int>(
      "Length Input to Count",
      get_count_from_length,
      mf::build::exec_presets::SomeSpanOrSingle<0, 1>());
 
  auto get_count_op = fn::FieldOperation::from(
      get_count_fn,
      {fn::Field<float>(std::make_shared<bke::CurveLengthFieldInput>()),
       length_field,
       fn::make_constant_field(keep_last_segment)});
 
  return fn::Field<int>(std::move(get_count_op));
}

static bool interpolate_attribute_to_curves(const StringRef attribute_id,
                                            const std::array<int, CURVE_TYPES_NUM> &type_counts)
{
  if (bke::attribute_name_is_anonymous(attribute_id)) {
    return true;
  }
  if (ELEM(attribute_id, "handle_type_left", "handle_type_right", "handle_left", "handle_right")) {
    return type_counts[CURVE_TYPE_BEZIER] != 0;
  }
  if (ELEM(attribute_id, "nurbs_weight")) {
    return type_counts[CURVE_TYPE_NURBS] != 0;
  }
  return true;
}

static bool interpolate_attribute_to_poly_curve(const StringRef attribute_id)
{
  static const Set<StringRef> no_interpolation{{
      "handle_type_left",
      "handle_type_right",
      "handle_right",
      "handle_left",
      "nurbs_weight",
  }};
  return !no_interpolation.contains(attribute_id);
}

static void retrieve_attribute_spans(const Span<StringRef> ids,
                                     const CurvesGeometry &src_curves,
                                     CurvesGeometry &dst_curves,
                                     Vector<GVArraySpan> &src,
                                     Vector<GMutableSpan> &dst,
                                     Vector<bke::GSpanAttributeWriter> &dst_attributes)
{
  const bke::AttributeAccessor src_attributes = src_curves.attributes();
  for (const int i : ids.index_range()) {
    const bke::GAttributeReader src_attribute = src_attributes.lookup(ids[i],
                                                                      bke::AttrDomain::Point);
    src.append(src_attribute.varray);
 
    const bke::AttrType data_type = bke::cpp_type_to_attribute_type(src_attribute.varray.type());
    bke::GSpanAttributeWriter dst_attribute =
        dst_curves.attributes_for_write().lookup_or_add_for_write_only_span(
            ids[i], bke::AttrDomain::Point, data_type);
    dst.append(dst_attribute.span);
    dst_attributes.append(std::move(dst_attribute));
  }
}
 
struct AttributesForResample : NonCopyable, NonMovable {
  Vector<GVArraySpan> src;
  Vector<GMutableSpan> dst;
 
  Vector<bke::GSpanAttributeWriter> dst_attributes;
 
  Vector<GVArraySpan> src_no_interpolation;
  Vector<GMutableSpan> dst_no_interpolation;
 
  Span<float3> src_evaluated_tangents;
  Span<float3> src_evaluated_normals;
  MutableSpan<float3> dst_tangents;
  MutableSpan<float3> dst_normals;
};

static void gather_point_attributes_to_interpolate(
    const CurvesGeometry &src_curves,
    CurvesGeometry &dst_curves,
    AttributesForResample &result,
    const ResampleCurvesOutputAttributeIDs &output_ids)
{
  VectorSet<StringRef> ids;
  VectorSet<StringRef> ids_no_interpolation;
  src_curves.attributes().foreach_attribute([&](const bke::AttributeIter &iter) {
    if (iter.domain != bke::AttrDomain::Point) {
      return;
    }
    if (iter.data_type == bke::AttrType::String) {
      return;
    }
    if (!interpolate_attribute_to_curves(iter.name, dst_curves.curve_type_counts())) {
      return;
    }
    if (interpolate_attribute_to_poly_curve(iter.name)) {
      ids.add_new(iter.name);
    }
    else {
      ids_no_interpolation.add_new(iter.name);
    }
  });
 
  /* Position is handled differently since it has non-generic interpolation for Bezier
   * curves and because the evaluated positions are cached for each evaluated point. */
  ids.remove_contained("position");
 
  retrieve_attribute_spans(
      ids, src_curves, dst_curves, result.src, result.dst, result.dst_attributes);
 
  /* Attributes that aren't interpolated like Bezier handles still have to be copied
   * to the result when there are any unselected curves of the corresponding type. */
  retrieve_attribute_spans(ids_no_interpolation,
                           src_curves,
                           dst_curves,
                           result.src_no_interpolation,
                           result.dst_no_interpolation,
                           result.dst_attributes);
 
  bke::MutableAttributeAccessor dst_attributes = dst_curves.attributes_for_write();
  if (output_ids.tangent_id) {
    result.src_evaluated_tangents = src_curves.evaluated_tangents();
    bke::GSpanAttributeWriter dst_attribute = dst_attributes.lookup_or_add_for_write_only_span(
        *output_ids.tangent_id, bke::AttrDomain::Point, bke::AttrType::Float3);
    result.dst_tangents = dst_attribute.span.typed<float3>();
    result.dst_attributes.append(std::move(dst_attribute));
  }
  if (output_ids.normal_id) {
    result.src_evaluated_normals = src_curves.evaluated_normals();
    bke::GSpanAttributeWriter dst_attribute = dst_attributes.lookup_or_add_for_write_only_span(
        *output_ids.normal_id, bke::AttrDomain::Point, bke::AttrType::Float3);
    result.dst_normals = dst_attribute.span.typed<float3>();
    result.dst_attributes.append(std::move(dst_attribute));
  }
}
 
static void copy_or_defaults_for_unselected_curves(const CurvesGeometry &src_curves,
                                                   const IndexMask &unselected_curves,
                                                   const AttributesForResample &attributes,
                                                   CurvesGeometry &dst_curves)
{
  const OffsetIndices src_points_by_curve = src_curves.points_by_curve();
  const OffsetIndices dst_points_by_curve = dst_curves.points_by_curve();
  array_utils::copy_group_to_group(src_points_by_curve,
                                   dst_points_by_curve,
                                   unselected_curves,
                                   src_curves.positions(),
                                   dst_curves.positions_for_write());
 
  for (const int i : attributes.src.index_range()) {
    array_utils::copy_group_to_group(src_points_by_curve,
                                     dst_points_by_curve,
                                     unselected_curves,
                                     attributes.src[i],
                                     attributes.dst[i]);
  }
  for (const int i : attributes.src_no_interpolation.index_range()) {
    array_utils::copy_group_to_group(src_points_by_curve,
                                     dst_points_by_curve,
                                     unselected_curves,
                                     attributes.src_no_interpolation[i],
                                     attributes.dst_no_interpolation[i]);
  }
 
  if (!attributes.dst_tangents.is_empty()) {
    bke::curves::fill_points(
        dst_points_by_curve, unselected_curves, float3(0), attributes.dst_tangents);
  }
  if (!attributes.dst_normals.is_empty()) {
    bke::curves::fill_points(
        dst_points_by_curve, unselected_curves, float3(0), attributes.dst_normals);
  }
}
 
static void normalize_span(MutableSpan<float3> data)
{
  for (const int i : data.index_range()) {
    data[i] = math::normalize(data[i]);
  }
}
 
static void normalize_curve_point_data(const IndexMaskSegment curve_selection,
                                       const OffsetIndices<int> points_by_curve,
                                       MutableSpan<float3> data)
{
  for (const int i_curve : curve_selection) {
    normalize_span(data.slice(points_by_curve[i_curve]));
  }
}

struct EvalDataBuffer {
  using AllocatorType = GuardedAlignedAllocator<>;
  /* Use a default alignment that works for all attribute types, and don't use the inline buffer
   * because it doesn't necessarily have the correct alignment. */
  Vector<std::byte, 0, AllocatorType> heap_allocated;
  alignas(AllocatorType::min_alignment) std::array<std::byte, 1024> inline_buffer;
 
  template<typename T> MutableSpan<T> resize(const int64_t size)
  {
    const int64_t size_in_bytes = sizeof(T) * size;
    if (size_in_bytes <= this->inline_buffer.size()) {
      return MutableSpan<std::byte>(this->inline_buffer).slice(0, size_in_bytes).cast<T>();
    }
    this->heap_allocated.resize(size_in_bytes);
    return this->heap_allocated.as_mutable_span().cast<T>();
  }
};
 
static void resample_to_uniform(const CurvesGeometry &src_curves,
                                const IndexMask &selection,
                                const ResampleCurvesOutputAttributeIDs &output_ids,
                                CurvesGeometry &dst_curves)
{
  if (src_curves.curves_range().is_empty()) {
    return;
  }
 
  const OffsetIndices src_points_by_curve = src_curves.points_by_curve();
  const OffsetIndices evaluated_points_by_curve = src_curves.evaluated_points_by_curve();
  const VArray<bool> curves_cyclic = src_curves.cyclic();
  const VArray<int8_t> curve_types = src_curves.curve_types();
  const Span<float3> evaluated_positions = src_curves.evaluated_positions();
 
  /* All resampled curves are poly curves. */
  dst_curves.fill_curve_types(selection, CURVE_TYPE_POLY);
 
  MutableSpan<float3> dst_positions = dst_curves.positions_for_write();
 
  AttributesForResample attributes;
  gather_point_attributes_to_interpolate(src_curves, dst_curves, attributes, output_ids);
 
  src_curves.ensure_evaluated_lengths();
 
  /* Sampling arbitrary attributes works by first interpolating them to the curve's standard
   * "evaluated points" and then interpolating that result with the uniform samples. This is
   * potentially wasteful when down-sampling a curve to many fewer points. There are two possible
   * solutions: only sample the necessary points for interpolation, or first sample curve
   * parameter/segment indices and evaluate the curve directly. */
  Array<int> sample_indices(dst_curves.points_num());
  Array<float> sample_factors(dst_curves.points_num());
 
  const OffsetIndices dst_points_by_curve = dst_curves.points_by_curve();
 
  /* Use a "for each group of curves: for each attribute: for each curve" pattern to work on
   * smaller sections of data that ideally fit into CPU cache better than simply one attribute at a
   * time or one curve at a time. */
  selection.foreach_segment(GrainSize(512), [&](const IndexMaskSegment selection_segment) {
    EvalDataBuffer evaluated_buffer;
 
    /* Gather uniform samples based on the accumulated lengths of the original curve. */
    for (const int i_curve : selection_segment) {
      const bool cyclic = curves_cyclic[i_curve];
      const IndexRange dst_points = dst_points_by_curve[i_curve];
      const Span<float> lengths = src_curves.evaluated_lengths_for_curve(i_curve, cyclic);
      if (lengths.is_empty()) {
        /* Handle curves with only one evaluated point. */
        sample_indices.as_mutable_span().slice(dst_points).fill(0);
        sample_factors.as_mutable_span().slice(dst_points).fill(0.0f);
      }
      else {
        length_parameterize::sample_uniform(lengths,
                                            !curves_cyclic[i_curve],
                                            sample_indices.as_mutable_span().slice(dst_points),
                                            sample_factors.as_mutable_span().slice(dst_points));
      }
    }
 
    /* For every attribute, evaluate attributes from every curve in the range in the original
     * curve's "evaluated points", then use linear interpolation to sample to the result. */
    for (const int i_attribute : attributes.dst.index_range()) {
      const CPPType &type = attributes.src[i_attribute].type();
      bke::attribute_math::convert_to_static_type(type, [&](auto dummy) {
        using T = decltype(dummy);
        Span<T> src = attributes.src[i_attribute].typed<T>();
        MutableSpan<T> dst = attributes.dst[i_attribute].typed<T>();
 
        for (const int i_curve : selection_segment) {
          const IndexRange src_points = src_points_by_curve[i_curve];
          const IndexRange dst_points = dst_points_by_curve[i_curve];
 
          if (curve_types[i_curve] == CURVE_TYPE_POLY) {
            length_parameterize::interpolate(src.slice(src_points),
                                             sample_indices.as_span().slice(dst_points),
                                             sample_factors.as_span().slice(dst_points),
                                             dst.slice(dst_points));
          }
          else {
            MutableSpan evaluated = evaluated_buffer.resize<T>(
                evaluated_points_by_curve[i_curve].size());
            src_curves.interpolate_to_evaluated(i_curve, src.slice(src_points), evaluated);
 
            length_parameterize::interpolate(evaluated.as_span(),
                                             sample_indices.as_span().slice(dst_points),
                                             sample_factors.as_span().slice(dst_points),
                                             dst.slice(dst_points));
          }
        }
      });
    }
 
    auto interpolate_evaluated_data = [&](const Span<float3> src, MutableSpan<float3> dst) {
      for (const int i_curve : selection_segment) {
        const IndexRange src_points = evaluated_points_by_curve[i_curve];
        const IndexRange dst_points = dst_points_by_curve[i_curve];
        length_parameterize::interpolate(src.slice(src_points),
                                         sample_indices.as_span().slice(dst_points),
                                         sample_factors.as_span().slice(dst_points),
                                         dst.slice(dst_points));
      }
    };
 
    /* Interpolate the evaluated positions to the resampled curves. */
    interpolate_evaluated_data(evaluated_positions, dst_positions);
 
    if (!attributes.dst_tangents.is_empty()) {
      interpolate_evaluated_data(attributes.src_evaluated_tangents, attributes.dst_tangents);
      normalize_curve_point_data(selection_segment, dst_points_by_curve, attributes.dst_tangents);
    }
    if (!attributes.dst_normals.is_empty()) {
      interpolate_evaluated_data(attributes.src_evaluated_normals, attributes.dst_normals);
      normalize_curve_point_data(selection_segment, dst_points_by_curve, attributes.dst_normals);
    }
 
    /* Fill the default value for non-interpolating attributes that still must be copied. */
    for (GMutableSpan dst : attributes.dst_no_interpolation) {
      for (const int i_curve : selection_segment) {
        const IndexRange dst_points = dst_points_by_curve[i_curve];
        dst.type().value_initialize_n(dst.slice(dst_points).data(), dst_points.size());
      }
    }
  });
 
  IndexMaskMemory memory;
  const IndexMask unselected = selection.complement(src_curves.curves_range(), memory);
  copy_or_defaults_for_unselected_curves(src_curves, unselected, attributes, dst_curves);
 
  for (bke::GSpanAttributeWriter &attribute : attributes.dst_attributes) {
    attribute.finish();
  }
}
 
static CurvesGeometry resample_to_uniform(const CurvesGeometry &src_curves,
                                          const fn::FieldContext &field_context,
                                          const fn::Field<bool> &selection_field,
                                          const fn::Field<int> &count_field,
                                          const ResampleCurvesOutputAttributeIDs &output_ids)
{
  if (src_curves.curves_range().is_empty()) {
    return {};
  }
  const OffsetIndices src_points_by_curve = src_curves.points_by_curve();
 
  CurvesGeometry dst_curves = bke::curves::copy_only_curve_domain(src_curves);
  /* Copy vertex groups from source curves to allow copying vertex group attributes. */
  BKE_defgroup_copy_list(&dst_curves.vertex_group_names, &src_curves.vertex_group_names);
  MutableSpan<int> dst_offsets = dst_curves.offsets_for_write();
 
  fn::FieldEvaluator evaluator{field_context, src_curves.curves_num()};
  evaluator.set_selection(selection_field);
  evaluator.add_with_destination(count_field, dst_offsets.drop_back(1));
  evaluator.evaluate();
  const IndexMask selection = evaluator.get_evaluated_selection_as_mask();
  IndexMaskMemory memory;
  const IndexMask unselected = selection.complement(src_curves.curves_range(), memory);
 
  /* Fill the counts for the curves that aren't selected and accumulate the counts into offsets. */
  offset_indices::copy_group_sizes(src_points_by_curve, unselected, dst_offsets);
  if (!offset_indices::accumulate_counts_to_offsets_with_overflow_check(dst_offsets)) {
    return {};
  }
  dst_curves.resize(dst_offsets.last(), dst_curves.curves_num());
 
  resample_to_uniform(src_curves, selection, output_ids, dst_curves);
 
  bke::curves::nurbs::copy_custom_knots(src_curves, selection, dst_curves);
  return dst_curves;
}
 
CurvesGeometry resample_to_count(const CurvesGeometry &src_curves,
                                 const IndexMask &selection,
                                 const VArray<int> &counts,
                                 const ResampleCurvesOutputAttributeIDs &output_ids)
{
  if (src_curves.curves_range().is_empty()) {
    return {};
  }
  const OffsetIndices src_points_by_curve = src_curves.points_by_curve();
 
  CurvesGeometry dst_curves = bke::curves::copy_only_curve_domain(src_curves);
  /* Copy vertex groups from source curves to allow copying vertex group attributes. */
  BKE_defgroup_copy_list(&dst_curves.vertex_group_names, &src_curves.vertex_group_names);
  MutableSpan<int> dst_offsets = dst_curves.offsets_for_write();
 
  array_utils::copy(counts, selection, dst_offsets);
 
  IndexMaskMemory memory;
  const IndexMask unselected = selection.complement(src_curves.curves_range(), memory);
 
  /* Fill the counts for the curves that aren't selected and accumulate the counts into offsets. */
  offset_indices::copy_group_sizes(src_points_by_curve, unselected, dst_offsets);
  /* We assume the counts are at least 1. */
  BLI_assert(std::all_of(dst_offsets.begin(),
                         dst_offsets.drop_back(1).end(),
                         [&](const int count) { return count > 0; }));
  offset_indices::accumulate_counts_to_offsets(dst_offsets);
  dst_curves.resize(dst_offsets.last(), dst_curves.curves_num());
 
  resample_to_uniform(src_curves, selection, output_ids, dst_curves);
 
  bke::curves::nurbs::copy_custom_knots(src_curves, selection, dst_curves);
  return dst_curves;
}
 
CurvesGeometry resample_to_count(const CurvesGeometry &src_curves,
                                 const fn::FieldContext &field_context,
                                 const fn::Field<bool> &selection_field,
                                 const fn::Field<int> &count_field,
                                 const ResampleCurvesOutputAttributeIDs &output_ids)
{
  return resample_to_uniform(src_curves,
                             field_context,
                             selection_field,
                             get_count_input_max_one(count_field),
                             output_ids);
}
 
CurvesGeometry resample_to_length(const CurvesGeometry &src_curves,
                                  const IndexMask &selection,
                                  const VArray<float> &sample_lengths,
                                  const ResampleCurvesOutputAttributeIDs &output_ids,
                                  const bool keep_last_segment)
{
  if (src_curves.curves_range().is_empty()) {
    return {};
  }
  const OffsetIndices src_points_by_curve = src_curves.points_by_curve();
  const VArray<bool> curves_cyclic = src_curves.cyclic();
 
  CurvesGeometry dst_curves = bke::curves::copy_only_curve_domain(src_curves);
  /* Copy vertex groups from source curves to allow copying vertex group attributes. */
  BKE_defgroup_copy_list(&dst_curves.vertex_group_names, &src_curves.vertex_group_names);
  MutableSpan<int> dst_offsets = dst_curves.offsets_for_write();
 
  src_curves.ensure_evaluated_lengths();
  selection.foreach_index(GrainSize(1024), [&](const int curve_i) {
    const float curve_length = src_curves.evaluated_length_total_for_curve(curve_i,
                                                                           curves_cyclic[curve_i]);
    dst_offsets[curve_i] = get_count_from_length(
        curve_length, sample_lengths[curve_i], keep_last_segment);
  });
 
  IndexMaskMemory memory;
  const IndexMask unselected = selection.complement(src_curves.curves_range(), memory);
 
  /* Fill the counts for the curves that aren't selected and accumulate the counts into offsets. */
  offset_indices::copy_group_sizes(src_points_by_curve, unselected, dst_offsets);
  offset_indices::accumulate_counts_to_offsets(dst_offsets);
  dst_curves.resize(dst_offsets.last(), dst_curves.curves_num());
 
  resample_to_uniform(src_curves, selection, output_ids, dst_curves);
 
  bke::curves::nurbs::copy_custom_knots(src_curves, selection, dst_curves);
  return dst_curves;
}
 
CurvesGeometry resample_to_length(const CurvesGeometry &src_curves,
                                  const fn::FieldContext &field_context,
                                  const fn::Field<bool> &selection_field,
                                  const fn::Field<float> &segment_length_field,
                                  const ResampleCurvesOutputAttributeIDs &output_ids,
                                  const bool keep_last_segment)
{
  return resample_to_uniform(src_curves,
                             field_context,
                             selection_field,
                             get_count_input_from_length(segment_length_field, keep_last_segment),
                             output_ids);
}
 
CurvesGeometry resample_to_evaluated(const CurvesGeometry &src_curves,
                                     const IndexMask &selection,
                                     const ResampleCurvesOutputAttributeIDs &output_ids)
{
  if (src_curves.curves_range().is_empty()) {
    return {};
  }
  const OffsetIndices src_points_by_curve = src_curves.points_by_curve();
  const OffsetIndices src_evaluated_points_by_curve = src_curves.evaluated_points_by_curve();
  const Span<float3> evaluated_positions = src_curves.evaluated_positions();
 
  IndexMaskMemory memory;
  const IndexMask unselected = selection.complement(src_curves.curves_range(), memory);
 
  CurvesGeometry dst_curves = bke::curves::copy_only_curve_domain(src_curves);
  /* Copy vertex groups from source curves to allow copying vertex group attributes. */
  BKE_defgroup_copy_list(&dst_curves.vertex_group_names, &src_curves.vertex_group_names);
  dst_curves.fill_curve_types(selection, CURVE_TYPE_POLY);
  MutableSpan<int> dst_offsets = dst_curves.offsets_for_write();
  offset_indices::copy_group_sizes(src_evaluated_points_by_curve, selection, dst_offsets);
  offset_indices::copy_group_sizes(src_points_by_curve, unselected, dst_offsets);
  offset_indices::accumulate_counts_to_offsets(dst_offsets);
  const OffsetIndices dst_points_by_curve = dst_curves.points_by_curve();
 
  dst_curves.resize(dst_offsets.last(), dst_curves.curves_num());
 
  MutableSpan<float3> dst_positions = dst_curves.positions_for_write();
 
  AttributesForResample attributes;
  gather_point_attributes_to_interpolate(src_curves, dst_curves, attributes, output_ids);
 
  src_curves.ensure_can_interpolate_to_evaluated();
  selection.foreach_segment(GrainSize(512), [&](const IndexMaskSegment selection_segment) {
    /* Evaluate generic point attributes directly to the result attributes. */
    for (const int i_attribute : attributes.dst.index_range()) {
      for (const int i_curve : selection_segment) {
        const IndexRange src_points = src_points_by_curve[i_curve];
        const IndexRange dst_points = dst_points_by_curve[i_curve];
        src_curves.interpolate_to_evaluated(i_curve,
                                            attributes.src[i_attribute].slice(src_points),
                                            attributes.dst[i_attribute].slice(dst_points));
      }
    }
 
    auto copy_evaluated_data = [&](const Span<float3> src, MutableSpan<float3> dst) {
      for (const int i_curve : selection_segment) {
        const IndexRange src_points = src_evaluated_points_by_curve[i_curve];
        const IndexRange dst_points = dst_points_by_curve[i_curve];
        dst.slice(dst_points).copy_from(src.slice(src_points));
      }
    };
 
    /* Copy the evaluated positions to the selected curves. */
    copy_evaluated_data(evaluated_positions, dst_positions);
 
    if (!attributes.dst_tangents.is_empty()) {
      copy_evaluated_data(attributes.src_evaluated_tangents, attributes.dst_tangents);
      normalize_curve_point_data(selection_segment, dst_points_by_curve, attributes.dst_tangents);
    }
    if (!attributes.dst_normals.is_empty()) {
      copy_evaluated_data(attributes.src_evaluated_normals, attributes.dst_normals);
      normalize_curve_point_data(selection_segment, dst_points_by_curve, attributes.dst_normals);
    }
 
    /* Fill the default value for non-interpolating attributes that still must be copied. */
    for (GMutableSpan dst : attributes.dst_no_interpolation) {
      for (const int i_curve : selection_segment) {
        const IndexRange dst_points = dst_points_by_curve[i_curve];
        dst.type().value_initialize_n(dst.slice(dst_points).data(), dst_points.size());
      }
    }
  });
 
  copy_or_defaults_for_unselected_curves(src_curves, unselected, attributes, dst_curves);
 
  for (bke::GSpanAttributeWriter &attribute : attributes.dst_attributes) {
    attribute.finish();
  }
 
  bke::curves::nurbs::copy_custom_knots(src_curves, selection, dst_curves);
  return dst_curves;
}
 
CurvesGeometry resample_to_evaluated(const CurvesGeometry &src_curves,
                                     const fn::FieldContext &field_context,
                                     const fn::Field<bool> &selection_field,
                                     const ResampleCurvesOutputAttributeIDs &output_ids)
{
  if (src_curves.curves_range().is_empty()) {
    return {};
  }
  fn::FieldEvaluator evaluator{field_context, src_curves.curves_num()};
  evaluator.set_selection(selection_field);
  evaluator.evaluate();
  return resample_to_evaluated(
      src_curves, evaluator.get_evaluated_selection_as_mask(), output_ids);
}
 
}  // namespace blender::geometry