Geometry Nodes: Port the trim curve node to the new data-block

The trim functionality is implemented in the geometry module, and
generalized a bit to be potentially useful for bisecting in the future.
The implementation is based on a helper type called `IndexRangeCyclic`
which allows iteration over all control points between two points on a
curve.

Catmull Rom curves are now supported-- trimmed without resampling first.
However, maintaining the exact shape is not possible. NURBS splines are
still converted to polylines using the evaluated curve concept.

Performance is equivalent or faster then a 3.1 build with regards to
node timings. Compared to 3.3 and 3.2, it's easy to observe test cases
where the node is at least 3 or 4 times faster.

Differential Revision: https://developer.blender.org/D14481

source/blender/blenkernel/BKE_attribute.hh

@@ -710,6 +710,19 @@ Vector<AttributeTransferData> retrieve_attributes_for_transfer(
     eAttrDomainMask domain_mask,
     const Set<std::string> &skip = {});
 
+/**
+ * Copy attributes for the domain based on the elementwise mask.
+ *
+ * \param mask_indices: Indexed elements to copy from the source data-block.
+ * \param domain: Attribute domain to transfer.
+ * \param skip: Named attributes to ignore/skip.
+ */
+void copy_attribute_domain(AttributeAccessor src_attributes,
+                           MutableAttributeAccessor dst_attributes,
+                           IndexMask selection,
+                           eAttrDomain domain,
+                           const Set<std::string> &skip = {});
+
 bool allow_procedural_attribute_access(StringRef attribute_name);
 extern const char *no_procedural_access_message;
 

source/blender/blenkernel/BKE_curves.hh

@@ -22,6 +22,7 @@
 #include "BLI_virtual_array.hh"
 
 #include "BKE_attribute.hh"
+#include "BKE_attribute_math.hh"
 
 namespace blender::bke {
 
@@ -161,6 +162,11 @@ class CurvesGeometry : public ::CurvesGeometry {
   IndexRange points_range() const;
   IndexRange curves_range() const;
 
+  /**
+   * Number of control points in the indexed curve.
+   */
+  int points_num_for_curve(const int index) const;
+
   /**
    * The index of the first point in every curve. The size of this span is one larger than the
    * number of curves. Consider using #points_for_curve rather than using the offsets directly.
@@ -531,6 +537,16 @@ bool segment_is_vector(Span<int8_t> handle_types_left,
                        Span<int8_t> handle_types_right,
                        int segment_index);
 
+/**
+ * True if the Bezier curve contains polygonal segments of HandleType::BEZIER_HANDLE_VECTOR.
+ *
+ * \param num_curve_points: Number of points in the curve.
+ * \param evaluated_size: Number of evaluated points in the curve.
+ * \param cyclic: If curve is cyclic.
+ * \param resolution: Curve resolution.
+ */
+bool has_vector_handles(int num_curve_points, int64_t evaluated_size, bool cyclic, int resolution);
+
 /**
  * Return true if the curve's last cyclic segment has a vector type.
  * This only makes a difference in the shape of cyclic curves.
@@ -693,6 +709,36 @@ void interpolate_to_evaluated(const GSpan src,
                               const Span<int> evaluated_offsets,
                               GMutableSpan dst);
 
+void calculate_basis(const float parameter, float r_weights[4]);
+
+/**
+ * Interpolate the control point values for the given parameter on the piecewise segment.
+ * \param a: Value associated with the first control point influencing the segment.
+ * \param d: Value associated with the fourth control point.
+ * \param parameter: Parameter in range [0, 1] to compute the interpolation for.
+ */
+template<typename T>
+T interpolate(const T &a, const T &b, const T &c, const T &d, const float parameter)
+{
+  float n[4];
+  calculate_basis(parameter, n);
+  /* TODO: Use DefaultMixer or other generic mixing in the basis evaluation function to simplify
+   * supporting more types. */
+  if constexpr (!is_same_any_v<T, float, float2, float3, float4, int8_t, int, int64_t>) {
+    T return_value;
+    attribute_math::DefaultMixer<T> mixer({&return_value, 1});
+    mixer.mix_in(0, a, n[0] * 0.5f);
+    mixer.mix_in(0, b, n[1] * 0.5f);
+    mixer.mix_in(0, c, n[2] * 0.5f);
+    mixer.mix_in(0, d, n[3] * 0.5f);
+    mixer.finalize();
+    return return_value;
+  }
+  else {
+    return 0.5f * (a * n[0] + b * n[1] + c * n[2] + d * n[3]);
+  }
+}
+
 }  // namespace catmull_rom
 
 /** \} */
@@ -807,6 +853,16 @@ inline IndexRange CurvesGeometry::curves_range() const
   return IndexRange(this->curves_num());
 }
 
+inline int CurvesGeometry::points_num_for_curve(const int index) const
+{
+  BLI_assert(this->curve_num > 0);
+  BLI_assert(this->curve_num > index);
+  BLI_assert(this->curve_offsets != nullptr);
+  const int offset = this->curve_offsets[index];
+  const int offset_next = this->curve_offsets[index + 1];
+  return offset_next - offset;
+}
+
 inline bool CurvesGeometry::is_single_type(const CurveType type) const
 {
   return this->curve_type_counts()[type] == this->curves_num();
@@ -833,6 +889,7 @@ inline IndexRange CurvesGeometry::points_for_curve(const int index) const
 {
   /* Offsets are not allocated when there are no curves. */
   BLI_assert(this->curve_num > 0);
+  BLI_assert(this->curve_num > index);
   BLI_assert(this->curve_offsets != nullptr);
   const int offset = this->curve_offsets[index];
   const int offset_next = this->curve_offsets[index + 1];
@@ -905,11 +962,13 @@ inline float CurvesGeometry::evaluated_length_total_for_curve(const int curve_in
 
 /** \} */
 
+namespace curves {
+
 /* -------------------------------------------------------------------- */
 /** \name Bezier Inline Methods
  * \{ */
 
-namespace curves::bezier {
+namespace bezier {
 
 inline bool point_is_sharp(const Span<int8_t> handle_types_left,
                            const Span<int8_t> handle_types_right,
@@ -929,14 +988,24 @@ inline bool segment_is_vector(const int8_t left, const int8_t right)
   return segment_is_vector(HandleType(left), HandleType(right));
 }
 
+inline bool has_vector_handles(const int num_curve_points,
+                               const int64_t evaluated_size,
+                               const bool cyclic,
+                               const int resolution)
+{
+  return evaluated_size - !cyclic != (int64_t)segments_num(num_curve_points, cyclic) * resolution;
+}
+
 inline float3 calculate_vector_handle(const float3 &point, const float3 &next_point)
 {
   return math::interpolate(point, next_point, 1.0f / 3.0f);
 }
 
+}  // namespace bezier
+
 /** \} */
 
-}  // namespace curves::bezier
+}  // namespace curves
 
 struct CurvesSurfaceTransforms {
   float4x4 curves_to_world;

source/blender/blenkernel/BKE_curves_utils.hh

@@ -11,9 +11,301 @@
 
 #include "BLI_function_ref.hh"
 #include "BLI_generic_pointer.hh"
+#include "BLI_index_range.hh"
 
 namespace blender::bke::curves {
 
+/* --------------------------------------------------------------------
+ * Utility structs.
+ */
+
+/**
+ * Reference to a piecewise segment on a spline curve.
+ */
+struct CurveSegment {
+  /**
+   * Index of the previous control/evaluated point on the curve. First point on the segment.
+   */
+  int index;
+  /**
+   * Index of the next control/evaluated point on the curve. Last point on the curve segment.
+   * Should be 0 for looped segments.
+   */
+  int next_index;
+};
+
+/**
+ * Reference to a point on a piecewise curve (spline).
+ *
+ * Tracks indices of the neighbouring control/evaluated point pair associated with the segment
+ * in which the point resides. Referenced point within the segment is defined by a
+ * normalized parameter in the range [0, 1].
+ */
+struct CurvePoint : public CurveSegment {
+  /**
+   * Normalized parameter in the range [0, 1] defining the point on the piecewise segment.
+   * Note that the curve point representation is not unique at segment endpoints.
+   */
+  float parameter;
+
+  /**
+   * True if the parameter is an integer and references a control/evaluated point.
+   */
+  inline bool is_controlpoint() const;
+
+  /*
+   * Compare if the points are equal.
+   */
+  inline bool operator==(const CurvePoint &other) const;
+  inline bool operator!=(const CurvePoint &other) const;
+
+  /**
+   * Compare if 'this' point comes before 'other'. Loop segment for cyclical curves counts
+   * as the first (least) segment.
+   */
+  inline bool operator<(const CurvePoint &other) const;
+};
+
+/**
+ * Cyclical index range. Iterates the interval [start, end).
+ */
+class IndexRangeCyclic {
+  /* Index to the start and end of the iterated range.
+   */
+  int64_t start_ = 0;
+  int64_t end_ = 0;
+  /* Index for the start and end of the entire iterable range which contains the iterated range
+   * (e.g. the point range for an indiviudal spline/curve within the entire Curves point domain).
+   */
+  int64_t range_start_ = 0;
+  int64_t range_end_ = 0;
+  /* Number of times the range end is passed when the range is iterated.
+   */
+  int64_t cycles_ = 0;
+
+  constexpr IndexRangeCyclic(int64_t begin,
+                             int64_t end,
+                             int64_t iterable_range_start,
+                             int64_t iterable_range_end,
+                             int64_t cycles)
+      : start_(begin),
+        end_(end),
+        range_start_(iterable_range_start),
+        range_end_(iterable_range_end),
+        cycles_(cycles)
+  {
+  }
+
+ public:
+  constexpr IndexRangeCyclic() = default;
+  ~IndexRangeCyclic() = default;
+
+  constexpr IndexRangeCyclic(int64_t start, int64_t end, IndexRange iterable_range, int64_t cycles)
+      : start_(start),
+        end_(end),
+        range_start_(iterable_range.first()),
+        range_end_(iterable_range.one_after_last()),
+        cycles_(cycles)
+  {
+  }
+
+  /**
+   * Create an iterator over the cyclical interval [start_index, end_index).
+   */
+  constexpr IndexRangeCyclic(int64_t start, int64_t end, IndexRange iterable_range)
+      : start_(start),
+        end_(end == iterable_range.one_after_last() ? iterable_range.first() : end),
+        range_start_(iterable_range.first()),
+        range_end_(iterable_range.one_after_last()),
+        cycles_(end < start)
+  {
+  }
+
+  /**
+   * Increment the range by adding the given number of indices to the beginning of the range.
+   */
+  constexpr IndexRangeCyclic push_forward(int n)
+  {
+    BLI_assert(n >= 0);
+    int64_t nstart = start_ - n;
+    int64_t cycles = cycles_;
+    if (nstart < range_start_) {
+
+      cycles += (int64_t)(n / (range_end_ - range_start_)) + (end_ < nstart) - (end_ < start_);
+    }
+    return {nstart, end_, range_start_, range_end_, cycles};
+  }
+  /**
+   * Increment the range by adding the given number of indices to the end of the range.
+   */
+  constexpr IndexRangeCyclic push_backward(int n)
+  {
+    BLI_assert(n >= 0);
+    int64_t new_end = end_ + n;
+    int64_t cycles = cycles_;
+    if (range_end_ <= new_end) {
+      cycles += (int64_t)(n / (range_end_ - range_start_)) + (new_end < start_) - (end_ < start_);
+    }
+    return {start_, new_end, range_start_, range_end_, cycles};
+  }
+
+  /**
+   * Get the index range for the curve buffer.
+   */
+  constexpr IndexRange curve_range() const
+  {
+    return IndexRange(range_start_, total_size());
+  }
+
+  /**
+   * Range between the first element up to the end of the range.
+   */
+  constexpr IndexRange range_before_loop() const
+  {
+    return IndexRange(start_, size_before_loop());
+  }
+
+  /**
+   * Range between the first element in the iterable range up to the last element in the range.
+   */
+  constexpr IndexRange range_after_loop() const
+  {
+    return IndexRange(range_start_, size_after_loop());
+  }
+
+  /**
+   * Size of the entire iterable range.
+   */
+  constexpr int64_t total_size() const
+  {
+    return range_end_ - range_start_;
+  }
+
+  /**
+   * Number of elements between the first element in the range up to the last element in the curve.
+   */
+  constexpr int64_t size_before_loop() const
+  {
+    return range_end_ - start_;
+  }
+
+  /**
+   * Number of elements between the first element in the iterable range up to the last element in
+   * the range.
+   */
+  constexpr int64_t size_after_loop() const
+  {
+    return end_ - range_start_;
+  }
+
+  /**
+   * Get number of elements iterated by the cyclical index range.
+   */
+  constexpr int64_t size() const
+  {
+    if (cycles_ > 0) {
+      return size_before_loop() + end_ + (cycles_ - 1) * (range_end_ - range_start_);
+    }
+    else {
+      return end_ - start_;
+    }
+  }
+
+  /**
+   * Return the number of times the iterator will cycle before ending.
+   */
+  constexpr int64_t cycles() const
+  {
+    return cycles_;
+  }
+
+  constexpr int64_t first() const
+  {
+    return start_;
+  }
+
+  constexpr int64_t one_after_last() const
+  {
+    return end_;
+  }
+
+  struct CyclicIterator; /* Forward declaration */
+
+  constexpr CyclicIterator begin() const
+  {
+    return CyclicIterator(range_start_, range_end_, start_, 0);
+  }
+
+  constexpr CyclicIterator end() const
+  {
+    return CyclicIterator(range_start_, range_end_, end_, cycles_);
+  }
+
+  struct CyclicIterator {
+    int64_t index_, begin_, end_, cycles_;
+
+    constexpr CyclicIterator(int64_t range_begin, int64_t range_end, int64_t index, int64_t cycles)
+        : index_(index), begin_(range_begin), end_(range_end), cycles_(cycles)
+    {
+      BLI_assert(range_begin <= index && index <= range_end);
+    }
+
+    constexpr CyclicIterator(const CyclicIterator &copy)
+        : index_(copy.index_), begin_(copy.begin_), end_(copy.end_), cycles_(copy.cycles_)
+    {
+    }
+    ~CyclicIterator() = default;
+
+    constexpr CyclicIterator &operator=(const CyclicIterator &copy)
+    {
+      if (this == &copy) {
+        return *this;
+      }
+      index_ = copy.index_;
+      begin_ = copy.begin_;
+      end_ = copy.end_;
+      cycles_ = copy.cycles_;
+      return *this;
+    }
+    constexpr CyclicIterator &operator++()
+    {
+      index_++;
+      if (index_ == end_) {
+        index_ = begin_;
+        cycles_++;
+      }
+      return *this;
+    }
+
+    void increment(int64_t n)
+    {
+      for (int i = 0; i < n; i++) {
+        ++*this;
+      }
+    }
+
+    constexpr const int64_t &operator*() const
+    {
+      return index_;
+    }
+
+    constexpr bool operator==(const CyclicIterator &other) const
+    {
+      return index_ == other.index_ && cycles_ == other.cycles_;
+    }
+    constexpr bool operator!=(const CyclicIterator &other) const
+    {
+      return !this->operator==(other);
+    }
+  };
+};
+
+/** \} */
+
+/* --------------------------------------------------------------------
+ * Utility functions.
+ */
+
 /**
  * Copy the provided point attribute values between all curves in the #curve_ranges index
  * ranges, assuming that all curves have the same number of control points in #src_curves
@@ -88,4 +380,40 @@ void foreach_curve_by_type(const VArray<int8_t> &types,
                            FunctionRef<void(IndexMask)> bezier_fn,
                            FunctionRef<void(IndexMask)> nurbs_fn);
 
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name #CurvePoint Inline Methods
+ * \{ */
+
+inline bool CurvePoint::is_controlpoint() const
+{
+  return parameter == 0.0 || parameter == 1.0;
+}
+
+inline bool CurvePoint::operator==(const CurvePoint &other) const
+{
+  return (parameter == other.parameter && index == other.index) ||
+         (parameter == 1.0 && other.parameter == 0.0 && next_index == other.index) ||
+         (parameter == 0.0 && other.parameter == 1.0 && index == other.next_index);
+}
+inline bool CurvePoint::operator!=(const CurvePoint &other) const
+{
+  return !this->operator==(other);
+}
+
+inline bool CurvePoint::operator<(const CurvePoint &other) const
+{
+  if (index == other.index) {
+    return parameter < other.parameter;
+  }
+  else {
+    /* Use next index for cyclic comparison due to loop segment < first segment. */
+    return next_index < other.next_index &&
+           !(next_index == other.index && parameter == 1.0 && other.parameter == 0.0);
+  }
+}
+
+/** \} */
+
 }  // namespace blender::bke::curves

source/blender/blenkernel/intern/attribute_access.cc

@@ -14,6 +14,7 @@
 #include "DNA_meshdata_types.h"
 #include "DNA_pointcloud_types.h"
 
+#include "BLI_array_utils.hh"
 #include "BLI_color.hh"
 #include "BLI_math_vec_types.hh"
 #include "BLI_span.hh"
@@ -974,6 +975,37 @@ Vector<AttributeTransferData> retrieve_attributes_for_transfer(
   return attributes;
 }
 
+void copy_attribute_domain(const AttributeAccessor src_attributes,
+                           MutableAttributeAccessor dst_attributes,
+                           const IndexMask selection,
+                           const eAttrDomain domain,
+                           const Set<std::string> &skip)
+{
+  src_attributes.for_all(
+      [&](const bke::AttributeIDRef &id, const bke::AttributeMetaData &meta_data) {
+        if (meta_data.domain != domain) {
+          return true;
+        }
+        if (id.is_named() && skip.contains(id.name())) {
+          return true;
+        }
+        if (!id.should_be_kept()) {
+          return true;
+        }
+
+        const GVArray src = src_attributes.lookup(id, meta_data.domain);
+        BLI_assert(src);
+
+        /* Copy attribute. */
+        GSpanAttributeWriter dst = dst_attributes.lookup_or_add_for_write_only_span(
+            id, domain, meta_data.data_type);
+        array_utils::copy(src, selection, dst.span);
+        dst.finish();
+
+        return true;
+      });
+}
+
 }  // namespace blender::bke
 
 /** \} */

source/blender/blenkernel/intern/curve_catmull_rom.cc

@@ -17,16 +17,14 @@ int calculate_evaluated_num(const int points_num, const bool cyclic, const int r
 }
 
 /* Adapted from Cycles #catmull_rom_basis_eval function. */
-template<typename T>
+void calculate_basis(const float parameter, float r_weights[4])
-static T calculate_basis(const T &a, const T &b, const T &c, const T &d, const float parameter)
 {
   const float t = parameter;
   const float s = 1.0f - parameter;
-  const float n0 = -t * s * s;
+  r_weights[0] = -t * s * s;
-  const float n1 = 2.0f + t * t * (3.0f * t - 5.0f);
+  r_weights[1] = 2.0f + t * t * (3.0f * t - 5.0f);
-  const float n2 = 2.0f + s * s * (3.0f * s - 5.0f);
+  r_weights[2] = 2.0f + s * s * (3.0f * s - 5.0f);
-  const float n3 = -s * t * t;
+  r_weights[3] = -s * t * t;
-  return 0.5f * (a * n0 + b * n1 + c * n2 + d * n3);
 }
 
 template<typename T>
@@ -35,7 +33,7 @@ static void evaluate_segment(const T &a, const T &b, const T &c, const T &d, Mut
   const float step = 1.0f / dst.size();
   dst.first() = b;
   for (const int i : dst.index_range().drop_front(1)) {
-    dst[i] = calculate_basis<T>(a, b, c, d, i * step);
+    dst[i] = interpolate<T>(a, b, c, d, i * step);
   }
 }
 

source/blender/blenlib/BLI_array_utils.hh

@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#pragma once
+
+#include "BLI_generic_span.hh"
+#include "BLI_generic_virtual_array.hh"
+#include "BLI_index_mask.hh"
+#include "BLI_task.hh"
+
+namespace blender::array_utils {
+
+/**
+ * Fill the destination span by copying masked values from the src array. Threaded based on
+ * grainsize.
+ */
+void copy(const GVArray &src, IndexMask selection, GMutableSpan dst, int64_t grain_size = 4096);
+
+/**
+ * Fill the destination span by copying values from the src array. Threaded based on
+ * grainsize.
+ */
+template<typename T>
+inline void copy(const Span<T> src,
+                 const IndexMask selection,
+                 MutableSpan<T> dst,
+                 const int64_t grain_size = 4096)
+{
+  threading::parallel_for(selection.index_range(), grain_size, [&](const IndexRange range) {
+    for (const int64_t index : selection.slice(range)) {
+      dst[index] = src[index];
+    }
+  });
+}
+
+}  // namespace blender::array_utils

source/blender/blenlib/CMakeLists.txt

@@ -47,6 +47,7 @@ set(SRC
   intern/array_store.c
   intern/array_store_utils.c
   intern/array_utils.c
+  intern/array_utils.cc
   intern/astar.c
   intern/bitmap.c
   intern/bitmap_draw_2d.c
@@ -164,6 +165,7 @@ set(SRC
   BLI_array_store.h
   BLI_array_store_utils.h
   BLI_array_utils.h
+  BLI_array_utils.hh
   BLI_asan.h
   BLI_assert.h
   BLI_astar.h

source/blender/blenlib/intern/array_utils.cc

@@ -0,0 +1,18 @@
+#include "BLI_array_utils.hh"
+#include "BLI_task.hh"
+
+namespace blender::array_utils {
+
+void copy(const GVArray &src,
+          const IndexMask selection,
+          GMutableSpan dst,
+          const int64_t grain_size)
+{
+  BLI_assert(src.type() == dst.type());
+  BLI_assert(src.size() == dst.size());
+  threading::parallel_for(selection.index_range(), grain_size, [&](const IndexRange range) {
+    src.materialize_to_uninitialized(selection.slice(range), dst.data());
+  });
+}
+
+}  // namespace blender::array_utils

source/blender/geometry/CMakeLists.txt

@@ -27,6 +27,7 @@ set(SRC
   intern/reverse_uv_sampler.cc
   intern/set_curve_type.cc
   intern/subdivide_curves.cc
+  intern/trim_curves.cc
   intern/uv_parametrizer.cc
 
   GEO_add_curves_on_mesh.hh
@@ -41,6 +42,7 @@ set(SRC
   GEO_reverse_uv_sampler.hh
   GEO_set_curve_type.hh
   GEO_subdivide_curves.hh
+  GEO_trim_curves.hh
   GEO_uv_parametrizer.h
 )
 

source/blender/geometry/GEO_trim_curves.hh

@@ -0,0 +1,32 @@
+#include "BLI_span.hh"
+
+#include "BKE_curves.hh"
+#include "BKE_curves_utils.hh"
+#include "BKE_geometry_set.hh"
+
+namespace blender::geometry {
+
+/*
+ * Create a new Curves instance by trimming the input curves. Copying the selected splines
+ * between the start and end points.
+ */
+bke::CurvesGeometry trim_curves(const bke::CurvesGeometry &src_curves,
+                                IndexMask selection,
+                                Span<bke::curves::CurvePoint> start_points,
+                                Span<bke::curves::CurvePoint> end_points);
+
+/**
+ * Find the point(s) and piecewise segment corresponding to the given distance along the length of
+ * the curve. Returns points on the evaluated curve for Catmull-Rom and NURBS splines.
+ *
+ * \param curves: Curve geometry to sample.
+ * \param lengths: Distance along the curve on form [0.0, length] to determine the point for.
+ * \param curve_indices: Curve index to lookup for each 'length', negative index are set to 0.
+ * \param is_normalized: If true, 'lengths' are normalized to the interval [0.0, 1.0].
+ */
+Array<bke::curves::CurvePoint, 12> lookup_curve_points(const bke::CurvesGeometry &curves,
+                                                       Span<float> lengths,
+                                                       Span<int64_t> curve_indices,
+                                                       bool is_normalized);
+
+}  // namespace blender::geometry

source/blender/nodes/geometry/nodes/node_geo_curve_trim.cc

@@ -9,12 +9,12 @@
 
 #include "NOD_socket_search_link.hh"
 
+#include "GEO_trim_curves.hh"
+
 #include "node_geometry_util.hh"
 
 namespace blender::nodes::node_geo_curve_trim_cc {
 
-using blender::attribute_math::mix2;
-
 NODE_STORAGE_FUNCS(NodeGeometryCurveTrim)
 
 static void node_declare(NodeDeclarationBuilder &b)
@@ -108,394 +108,6 @@ static void node_gather_link_searches(GatherLinkSearchOpParams &params)
   }
 }
 
-struct TrimLocation {
-  /* Control point index at the start side of the trim location. */
-  int left_index;
-  /* Control point index at the end of the trim location's segment. */
-  int right_index;
-  /* The factor between the left and right indices. */
-  float factor;
-};
-
-template<typename T>
-static void shift_slice_to_start(MutableSpan<T> data, const int start_index, const int num)
-{
-  BLI_assert(start_index + num - 1 <= data.size());
-  memmove(data.data(), &data[start_index], sizeof(T) * num);
-}
-
-/* Shift slice to start of span and modifies start and end data. */
-template<typename T>
-static void linear_trim_data(const TrimLocation &start,
-                             const TrimLocation &end,
-                             MutableSpan<T> data)
-{
-  const int num = end.right_index - start.left_index + 1;
-
-  if (start.left_index > 0) {
-    shift_slice_to_start<T>(data, start.left_index, num);
-  }
-
-  const T start_data = mix2<T>(start.factor, data.first(), data[1]);
-  const T end_data = mix2<T>(end.factor, data[num - 2], data[num - 1]);
-
-  data.first() = start_data;
-  data[num - 1] = end_data;
-}
-
-/**
- * Identical operation as #linear_trim_data, but copy data to a new #MutableSpan rather than
- * modifying the original data.
- */
-template<typename T>
-static void linear_trim_to_output_data(const TrimLocation &start,
-                                       const TrimLocation &end,
-                                       Span<T> src,
-                                       MutableSpan<T> dst)
-{
-  const int num = end.right_index - start.left_index + 1;
-
-  const T start_data = mix2<T>(start.factor, src[start.left_index], src[start.right_index]);
-  const T end_data = mix2<T>(end.factor, src[end.left_index], src[end.right_index]);
-
-  dst.copy_from(src.slice(start.left_index, num));
-  dst.first() = start_data;
-  dst.last() = end_data;
-}
-
-/* Look up the control points to the left and right of factor, and get the factor between them. */
-static TrimLocation lookup_control_point_position(const Spline::LookupResult &lookup,
-                                                  const BezierSpline &spline)
-{
-  Span<int> offsets = spline.control_point_offsets();
-
-  const int *offset = std::lower_bound(offsets.begin(), offsets.end(), lookup.evaluated_index);
-  const int index = offset - offsets.begin();
-
-  const int left = offsets[index] > lookup.evaluated_index ? index - 1 : index;
-  const int right = left == (spline.size() - 1) ? 0 : left + 1;
-
-  const float offset_in_segment = lookup.evaluated_index + lookup.factor - offsets[left];
-  const int segment_eval_num = offsets[left + 1] - offsets[left];
-  const float factor = std::clamp(offset_in_segment / segment_eval_num, 0.0f, 1.0f);
-
-  return {left, right, factor};
-}
-
-static void trim_poly_spline(Spline &spline,
-                             const Spline::LookupResult &start_lookup,
-                             const Spline::LookupResult &end_lookup)
-{
-  /* Poly splines have a 1 to 1 mapping between control points and evaluated points. */
-  const TrimLocation start = {
-      start_lookup.evaluated_index, start_lookup.next_evaluated_index, start_lookup.factor};
-  const TrimLocation end = {
-      end_lookup.evaluated_index, end_lookup.next_evaluated_index, end_lookup.factor};
-
-  const int num = end.right_index - start.left_index + 1;
-
-  linear_trim_data<float3>(start, end, spline.positions());
-  linear_trim_data<float>(start, end, spline.radii());
-  linear_trim_data<float>(start, end, spline.tilts());
-
-  spline.attributes.foreach_attribute(
-      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &UNUSED(meta_data)) {
-        std::optional<GMutableSpan> src = spline.attributes.get_for_write(attribute_id);
-        BLI_assert(src);
-        attribute_math::convert_to_static_type(src->type(), [&](auto dummy) {
-          using T = decltype(dummy);
-          linear_trim_data<T>(start, end, src->typed<T>());
-        });
-        return true;
-      },
-      ATTR_DOMAIN_POINT);
-
-  spline.resize(num);
-}
-
-/**
- * Trim NURB splines by converting to a poly spline.
- */
-static PolySpline trim_nurbs_spline(const Spline &spline,
-                                    const Spline::LookupResult &start_lookup,
-                                    const Spline::LookupResult &end_lookup)
-{
-  /* Since this outputs a poly spline, the evaluated indices are the control point indices. */
-  const TrimLocation start = {
-      start_lookup.evaluated_index, start_lookup.next_evaluated_index, start_lookup.factor};
-  const TrimLocation end = {
-      end_lookup.evaluated_index, end_lookup.next_evaluated_index, end_lookup.factor};
-
-  const int num = end.right_index - start.left_index + 1;
-
-  /* Create poly spline and copy trimmed data to it. */
-  PolySpline new_spline;
-  new_spline.resize(num);
-
-  /* Copy generic attribute data. */
-  spline.attributes.foreach_attribute(
-      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
-        std::optional<GSpan> src = spline.attributes.get_for_read(attribute_id);
-        BLI_assert(src);
-        if (!new_spline.attributes.create(attribute_id, meta_data.data_type)) {
-          BLI_assert_unreachable();
-          return false;
-        }
-        std::optional<GMutableSpan> dst = new_spline.attributes.get_for_write(attribute_id);
-        BLI_assert(dst);
-
-        attribute_math::convert_to_static_type(src->type(), [&](auto dummy) {
-          using T = decltype(dummy);
-          VArray<T> eval_data = spline.interpolate_to_evaluated<T>(src->typed<T>());
-          linear_trim_to_output_data<T>(
-              start, end, eval_data.get_internal_span(), dst->typed<T>());
-        });
-        return true;
-      },
-      ATTR_DOMAIN_POINT);
-
-  linear_trim_to_output_data<float3>(
-      start, end, spline.evaluated_positions(), new_spline.positions());
-
-  VArray<float> evaluated_radii = spline.interpolate_to_evaluated(spline.radii());
-  linear_trim_to_output_data<float>(
-      start, end, evaluated_radii.get_internal_span(), new_spline.radii());
-
-  VArray<float> evaluated_tilts = spline.interpolate_to_evaluated(spline.tilts());
-  linear_trim_to_output_data<float>(
-      start, end, evaluated_tilts.get_internal_span(), new_spline.tilts());
-
-  return new_spline;
-}
-
-/**
- * Trim Bezier splines by adjusting the first and last handles
- * and control points to maintain the original shape.
- */
-static void trim_bezier_spline(Spline &spline,
-                               const Spline::LookupResult &start_lookup,
-                               const Spline::LookupResult &end_lookup)
-{
-  BezierSpline &bezier_spline = static_cast<BezierSpline &>(spline);
-
-  const TrimLocation start = lookup_control_point_position(start_lookup, bezier_spline);
-  TrimLocation end = lookup_control_point_position(end_lookup, bezier_spline);
-
-  const Span<int> control_offsets = bezier_spline.control_point_offsets();
-
-  /* The number of control points in the resulting spline. */
-  const int num = end.right_index - start.left_index + 1;
-
-  /* Trim the spline attributes. Done before end.factor recalculation as it needs
-   * the original end.factor value. */
-  linear_trim_data<float>(start, end, bezier_spline.radii());
-  linear_trim_data<float>(start, end, bezier_spline.tilts());
-  spline.attributes.foreach_attribute(
-      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &UNUSED(meta_data)) {
-        std::optional<GMutableSpan> src = spline.attributes.get_for_write(attribute_id);
-        BLI_assert(src);
-        attribute_math::convert_to_static_type(src->type(), [&](auto dummy) {
-          using T = decltype(dummy);
-          linear_trim_data<T>(start, end, src->typed<T>());
-        });
-        return true;
-      },
-      ATTR_DOMAIN_POINT);
-
-  /* Recalculate end.factor if the `num` is two, because the adjustment in the
-   * position of the control point of the spline to the left of the new end point will change the
-   * factor between them. */
-  if (num == 2) {
-    if (start_lookup.factor == 1.0f) {
-      end.factor = 0.0f;
-    }
-    else {
-      end.factor = (end_lookup.evaluated_index + end_lookup.factor -
-                    (start_lookup.evaluated_index + start_lookup.factor)) /
-                   (control_offsets[end.right_index] -
-                    (start_lookup.evaluated_index + start_lookup.factor));
-      end.factor = std::clamp(end.factor, 0.0f, 1.0f);
-    }
-  }
-
-  BezierSpline::InsertResult start_point = bezier_spline.calculate_segment_insertion(
-      start.left_index, start.right_index, start.factor);
-
-  /* Update the start control point parameters so they are used calculating the new end point. */
-  bezier_spline.positions()[start.left_index] = start_point.position;
-  bezier_spline.handle_positions_right()[start.left_index] = start_point.right_handle;
-  bezier_spline.handle_positions_left()[start.right_index] = start_point.handle_next;
-
-  const BezierSpline::InsertResult end_point = bezier_spline.calculate_segment_insertion(
-      end.left_index, end.right_index, end.factor);
-
-  /* If `num` is two, then the start point right handle needs to change to reflect the end point
-   * previous handle update. */
-  if (num == 2) {
-    start_point.right_handle = end_point.handle_prev;
-  }
-
-  /* Shift control point position data to start at beginning of array. */
-  if (start.left_index > 0) {
-    shift_slice_to_start(bezier_spline.positions(), start.left_index, num);
-    shift_slice_to_start(bezier_spline.handle_positions_left(), start.left_index, num);
-    shift_slice_to_start(bezier_spline.handle_positions_right(), start.left_index, num);
-  }
-
-  bezier_spline.positions().first() = start_point.position;
-  bezier_spline.positions()[num - 1] = end_point.position;
-
-  bezier_spline.handle_positions_left().first() = start_point.left_handle;
-  bezier_spline.handle_positions_left()[num - 1] = end_point.left_handle;
-
-  bezier_spline.handle_positions_right().first() = start_point.right_handle;
-  bezier_spline.handle_positions_right()[num - 1] = end_point.right_handle;
-
-  /* If there is at least one control point between the endpoints, update the control
-   * point handle to the right of the start point and to the left of the end point. */
-  if (num > 2) {
-    bezier_spline.handle_positions_left()[start.right_index - start.left_index] =
-        start_point.handle_next;
-    bezier_spline.handle_positions_right()[end.left_index - start.left_index] =
-        end_point.handle_prev;
-  }
-
-  bezier_spline.resize(num);
-}
-
-static void trim_spline(SplinePtr &spline,
-                        const Spline::LookupResult start,
-                        const Spline::LookupResult end)
-{
-  switch (spline->type()) {
-    case CURVE_TYPE_BEZIER:
-      trim_bezier_spline(*spline, start, end);
-      break;
-    case CURVE_TYPE_POLY:
-      trim_poly_spline(*spline, start, end);
-      break;
-    case CURVE_TYPE_NURBS:
-      spline = std::make_unique<PolySpline>(trim_nurbs_spline(*spline, start, end));
-      break;
-    case CURVE_TYPE_CATMULL_ROM:
-      BLI_assert_unreachable();
-      spline = {};
-  }
-  spline->mark_cache_invalid();
-}
-
-template<typename T>
-static void to_single_point_data(const TrimLocation &trim, MutableSpan<T> data)
-{
-  data.first() = mix2<T>(trim.factor, data[trim.left_index], data[trim.right_index]);
-}
-template<typename T>
-static void to_single_point_data(const TrimLocation &trim, Span<T> src, MutableSpan<T> dst)
-{
-  dst.first() = mix2<T>(trim.factor, src[trim.left_index], src[trim.right_index]);
-}
-
-static void to_single_point_bezier(Spline &spline, const Spline::LookupResult &lookup)
-{
-  BezierSpline &bezier = static_cast<BezierSpline &>(spline);
-
-  const TrimLocation trim = lookup_control_point_position(lookup, bezier);
-
-  const BezierSpline::InsertResult new_point = bezier.calculate_segment_insertion(
-      trim.left_index, trim.right_index, trim.factor);
-  bezier.positions().first() = new_point.position;
-  bezier.handle_types_left().first() = BEZIER_HANDLE_FREE;
-  bezier.handle_types_right().first() = BEZIER_HANDLE_FREE;
-  bezier.handle_positions_left().first() = new_point.left_handle;
-  bezier.handle_positions_right().first() = new_point.right_handle;
-
-  to_single_point_data<float>(trim, bezier.radii());
-  to_single_point_data<float>(trim, bezier.tilts());
-  spline.attributes.foreach_attribute(
-      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &UNUSED(meta_data)) {
-        std::optional<GMutableSpan> data = spline.attributes.get_for_write(attribute_id);
-        attribute_math::convert_to_static_type(data->type(), [&](auto dummy) {
-          using T = decltype(dummy);
-          to_single_point_data<T>(trim, data->typed<T>());
-        });
-        return true;
-      },
-      ATTR_DOMAIN_POINT);
-  spline.resize(1);
-}
-
-static void to_single_point_poly(Spline &spline, const Spline::LookupResult &lookup)
-{
-  const TrimLocation trim{lookup.evaluated_index, lookup.next_evaluated_index, lookup.factor};
-
-  to_single_point_data<float3>(trim, spline.positions());
-  to_single_point_data<float>(trim, spline.radii());
-  to_single_point_data<float>(trim, spline.tilts());
-  spline.attributes.foreach_attribute(
-      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &UNUSED(meta_data)) {
-        std::optional<GMutableSpan> data = spline.attributes.get_for_write(attribute_id);
-        attribute_math::convert_to_static_type(data->type(), [&](auto dummy) {
-          using T = decltype(dummy);
-          to_single_point_data<T>(trim, data->typed<T>());
-        });
-        return true;
-      },
-      ATTR_DOMAIN_POINT);
-  spline.resize(1);
-}
-
-static PolySpline to_single_point_nurbs(const Spline &spline, const Spline::LookupResult &lookup)
-{
-  /* Since this outputs a poly spline, the evaluated indices are the control point indices. */
-  const TrimLocation trim{lookup.evaluated_index, lookup.next_evaluated_index, lookup.factor};
-
-  /* Create poly spline and copy trimmed data to it. */
-  PolySpline new_spline;
-  new_spline.resize(1);
-
-  spline.attributes.foreach_attribute(
-      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
-        new_spline.attributes.create(attribute_id, meta_data.data_type);
-        std::optional<GSpan> src = spline.attributes.get_for_read(attribute_id);
-        std::optional<GMutableSpan> dst = new_spline.attributes.get_for_write(attribute_id);
-        attribute_math::convert_to_static_type(src->type(), [&](auto dummy) {
-          using T = decltype(dummy);
-          VArray<T> eval_data = spline.interpolate_to_evaluated<T>(src->typed<T>());
-          to_single_point_data<T>(trim, eval_data.get_internal_span(), dst->typed<T>());
-        });
-        return true;
-      },
-      ATTR_DOMAIN_POINT);
-
-  to_single_point_data<float3>(trim, spline.evaluated_positions(), new_spline.positions());
-
-  VArray<float> evaluated_radii = spline.interpolate_to_evaluated(spline.radii());
-  to_single_point_data<float>(trim, evaluated_radii.get_internal_span(), new_spline.radii());
-
-  VArray<float> evaluated_tilts = spline.interpolate_to_evaluated(spline.tilts());
-  to_single_point_data<float>(trim, evaluated_tilts.get_internal_span(), new_spline.tilts());
-
-  return new_spline;
-}
-
-static void to_single_point_spline(SplinePtr &spline, const Spline::LookupResult &lookup)
-{
-  switch (spline->type()) {
-    case CURVE_TYPE_BEZIER:
-      to_single_point_bezier(*spline, lookup);
-      break;
-    case CURVE_TYPE_POLY:
-      to_single_point_poly(*spline, lookup);
-      break;
-    case CURVE_TYPE_NURBS:
-      spline = std::make_unique<PolySpline>(to_single_point_nurbs(*spline, lookup));
-      break;
-    case CURVE_TYPE_CATMULL_ROM:
-      BLI_assert_unreachable();
-      spline = {};
-  }
-}
-
 static void geometry_set_curve_trim(GeometrySet &geometry_set,
                                     const GeometryNodeCurveSampleMode mode,
                                     Field<float> &start_field,
@@ -505,68 +117,49 @@ static void geometry_set_curve_trim(GeometrySet &geometry_set,
     return;
   }
   const Curves &src_curves_id = *geometry_set.get_curves_for_read();
-  const bke::CurvesGeometry &curves = bke::CurvesGeometry::wrap(src_curves_id.geometry);
+  const bke::CurvesGeometry &src_curves = bke::CurvesGeometry::wrap(src_curves_id.geometry);
+  if (src_curves.curves_num() == 0) {
+    return;
+  }
 
-  bke::CurvesFieldContext field_context{curves, ATTR_DOMAIN_CURVE};
+  bke::CurvesFieldContext field_context{src_curves, ATTR_DOMAIN_CURVE};
-  fn::FieldEvaluator evaluator{field_context, curves.curves_num()};
+  fn::FieldEvaluator evaluator{field_context, src_curves.curves_num()};
   evaluator.add(start_field);
   evaluator.add(end_field);
   evaluator.evaluate();
   const VArray<float> starts = evaluator.get_evaluated<float>(0);
   const VArray<float> ends = evaluator.get_evaluated<float>(1);
 
-  std::unique_ptr<CurveEval> curve = curves_to_curve_eval(src_curves_id);
+  const VArray<bool> cyclic = src_curves.cyclic();
-  MutableSpan<SplinePtr> splines = curve->splines();
 
-  threading::parallel_for(splines.index_range(), 128, [&](IndexRange range) {
+  /* If node length input is on form [0, 1] instead of [0, length]*/
-    for (const int i : range) {
+  const bool normalized_length_lookup = mode == GEO_NODE_CURVE_SAMPLE_FACTOR;
-      SplinePtr &spline = splines[i];
 
-      /* Currently trimming cyclic splines is not supported. It could be in the future though. */
+  /* Stack start + end field. */
-      if (spline->is_cyclic()) {
+  Vector<float> length_factors(src_curves.curves_num() * 2);
-        continue;
+  Vector<int64_t> lookup_indices(src_curves.curves_num() * 2);
-      }
+  threading::parallel_for(src_curves.curves_range(), 512, [&](IndexRange curve_range) {
-
+    for (const int64_t curve_i : curve_range) {
-      if (spline->evaluated_edges_num() == 0) {
+      const bool negative_trim = !cyclic[curve_i] && starts[curve_i] > ends[curve_i];
-        continue;
+      length_factors[curve_i] = starts[curve_i];
-      }
+      length_factors[curve_i + src_curves.curves_num()] = negative_trim ? starts[curve_i] :
-
+                                                                          ends[curve_i];
-      const float length = spline->length();
+      lookup_indices[curve_i] = curve_i;
-      if (length == 0.0f) {
+      lookup_indices[curve_i + src_curves.curves_num()] = curve_i;
-        continue;
-      }
-
-      const float start = starts[i];
-      const float end = ends[i];
-
-      /* When the start and end samples are reversed, instead of implicitly reversing the spline
-       * or switching the parameters, create a single point spline with the end sample point. */
-      if (end <= start) {
-        if (mode == GEO_NODE_CURVE_SAMPLE_LENGTH) {
-          to_single_point_spline(spline,
-                                 spline->lookup_evaluated_length(std::clamp(start, 0.0f, length)));
-        }
-        else {
-          to_single_point_spline(spline,
-                                 spline->lookup_evaluated_factor(std::clamp(start, 0.0f, 1.0f)));
-        }
-        continue;
-      }
-
-      if (mode == GEO_NODE_CURVE_SAMPLE_LENGTH) {
-        trim_spline(spline,
-                    spline->lookup_evaluated_length(std::clamp(start, 0.0f, length)),
-                    spline->lookup_evaluated_length(std::clamp(end, 0.0f, length)));
-      }
-      else {
-        trim_spline(spline,
-                    spline->lookup_evaluated_factor(std::clamp(start, 0.0f, 1.0f)),
-                    spline->lookup_evaluated_factor(std::clamp(end, 0.0f, 1.0f)));
-      }
     }
   });
 
-  Curves *dst_curves_id = curve_eval_to_curves(*curve);
+  /* Create curve trim lookup table. */
+  Array<bke::curves::CurvePoint, 12> point_lookups = geometry::lookup_curve_points(
+      src_curves, length_factors, lookup_indices, normalized_length_lookup);
+
+  bke::CurvesGeometry dst_curves = geometry::trim_curves(
+      src_curves,
+      src_curves.curves_range().as_span(),
+      point_lookups.as_span().slice(0, src_curves.curves_num()),
+      point_lookups.as_span().slice(src_curves.curves_num(), src_curves.curves_num()));
+
+  Curves *dst_curves_id = bke::curves_new_nomain(std::move(dst_curves));
   bke::curves_copy_parameters(src_curves_id, *dst_curves_id);
   geometry_set.replace_curves(dst_curves_id);
 }