Cleanup: Refactor spline copying functions

Make the virtual functions protected and simpler, so that the logic is
better contained in the base class's implementation. Also introduce a
`copy_without_attributes` method to be used for realizing instances.

4 files changed, 86 insertions, 22 deletions

diff --git a/source/blender/blenkernel/intern/spline_base.cc b/source/blender/blenkernel/intern/spline_base.cc
index c18f44e07b2..aa0d95d4d61 100644
--- a/source/blender/blenkernel/intern/spline_base.cc
+++ b/source/blender/blenkernel/intern/spline_base.cc
@@ -40,6 +40,60 @@ Spline::Type Spline::type() const
   return type_;
 }
 
+void Spline::copy_base_settings(const Spline &src, Spline &dst)
+{
+  dst.normal_mode = src.normal_mode;
+  dst.is_cyclic_ = src.is_cyclic_;
+}
+
+static SplinePtr create_spline(const Spline::Type type)
+{
+  switch (type) {
+    case Spline::Type::Poly:
+      return std::make_unique<PolySpline>();
+    case Spline::Type::Bezier:
+      return std::make_unique<BezierSpline>();
+    case Spline::Type::NURBS:
+      return std::make_unique<NURBSpline>();
+  }
+  BLI_assert_unreachable();
+  return {};
+}
+
+/**
+ * Return a new spline with the same data, settings, and attributes.
+ */
+SplinePtr Spline::copy() const
+{
+  SplinePtr dst = this->copy_without_attributes();
+  dst->attributes = this->attributes;
+  return dst;
+}
+
+/**
+ * Return a new spline with the same type and settings like "cyclic", but without any data.
+ */
+SplinePtr Spline::copy_only_settings() const
+{
+  SplinePtr dst = create_spline(type_);
+  this->copy_base_settings(*this, *dst);
+  this->copy_settings(*dst);
+  return dst;
+}
+
+/**
+ * The same as #copy, but skips copying dynamic attributes to the new spline.
+ */
+SplinePtr Spline::copy_without_attributes() const
+{
+  SplinePtr dst = this->copy_only_settings();
+  this->copy_data(*dst);
+
+  /* Though the attributes storage is empty, it still needs to know the correct size. */
+  dst->attributes.reallocate(dst->size());
+  return dst;
+}
+
 void Spline::translate(const blender::float3 &translation)
 {
   for (float3 &position : this->positions()) {
diff --git a/source/blender/blenkernel/intern/spline_bezier.cc b/source/blender/blenkernel/intern/spline_bezier.cc
index daae03167ef..02d26ac715b 100644
--- a/source/blender/blenkernel/intern/spline_bezier.cc
+++ b/source/blender/blenkernel/intern/spline_bezier.cc
@@ -29,17 +29,22 @@ using blender::fn::GVArray;
 using blender::fn::GVArray_For_ArrayContainer;
 using blender::fn::GVArrayPtr;
 
-SplinePtr BezierSpline::copy() const
+void BezierSpline::copy_settings(Spline &dst) const
 {
-  return std::make_unique<BezierSpline>(*this);
+  BezierSpline &bezier = static_cast<BezierSpline &>(dst);
+  bezier.resolution_ = resolution_;
 }
 
-SplinePtr BezierSpline::copy_settings() const
+void BezierSpline::copy_data(Spline &dst) const
 {
-  std::unique_ptr<BezierSpline> copy = std::make_unique<BezierSpline>();
-  copy_base_settings(*this, *copy);
-  copy->resolution_ = resolution_;
-  return copy;
+  BezierSpline &bezier = static_cast<BezierSpline &>(dst);
+  bezier.positions_ = positions_;
+  bezier.handle_types_left_ = handle_types_left_;
+  bezier.handle_positions_left_ = handle_positions_left_;
+  bezier.handle_types_right_ = handle_types_right_;
+  bezier.handle_positions_right_ = handle_positions_right_;
+  bezier.radii_ = radii_;
+  bezier.tilts_ = tilts_;
 }
 
 int BezierSpline::size() const
diff --git a/source/blender/blenkernel/intern/spline_nurbs.cc b/source/blender/blenkernel/intern/spline_nurbs.cc
index 31ac23589be..85fb9730e83 100644
--- a/source/blender/blenkernel/intern/spline_nurbs.cc
+++ b/source/blender/blenkernel/intern/spline_nurbs.cc
@@ -31,19 +31,23 @@ using blender::fn::GVArray_For_ArrayContainer;
 using blender::fn::GVArray_Typed;
 using blender::fn::GVArrayPtr;
 
-SplinePtr NURBSpline::copy() const
+void NURBSpline::copy_settings(Spline &dst) const
 {
-  return std::make_unique<NURBSpline>(*this);
+  NURBSpline &nurbs = static_cast<NURBSpline &>(dst);
+  nurbs.knots_mode = knots_mode;
+  nurbs.resolution_ = resolution_;
+  nurbs.order_ = order_;
 }
 
-SplinePtr NURBSpline::copy_settings() const
+void NURBSpline::copy_data(Spline &dst) const
 {
-  std::unique_ptr<NURBSpline> copy = std::make_unique<NURBSpline>();
-  copy_base_settings(*this, *copy);
-  copy->knots_mode = knots_mode;
-  copy->resolution_ = resolution_;
-  copy->order_ = order_;
-  return copy;
+  NURBSpline &nurbs = static_cast<NURBSpline &>(dst);
+  nurbs.positions_ = positions_;
+  nurbs.weights_ = weights_;
+  nurbs.knots_ = knots_;
+  nurbs.knots_dirty_ = false;
+  nurbs.radii_ = radii_;
+  nurbs.tilts_ = tilts_;
 }
 
 int NURBSpline::size() const
diff --git a/source/blender/blenkernel/intern/spline_poly.cc b/source/blender/blenkernel/intern/spline_poly.cc
index e344b8d4910..dfd24b2566e 100644
--- a/source/blender/blenkernel/intern/spline_poly.cc
+++ b/source/blender/blenkernel/intern/spline_poly.cc
@@ -25,16 +25,17 @@ using blender::Span;
 using blender::fn::GVArray;
 using blender::fn::GVArrayPtr;
 
-SplinePtr PolySpline::copy() const
+void PolySpline::copy_settings(Spline &UNUSED(dst)) const
 {
-  return std::make_unique<PolySpline>(*this);
+  /* Poly splines have no settings not covered by the base class. */
 }
 
-SplinePtr PolySpline::copy_settings() const
+void PolySpline::copy_data(Spline &dst) const
 {
-  std::unique_ptr<PolySpline> copy = std::make_unique<PolySpline>();
-  copy_base_settings(*this, *copy);
-  return copy;
+  PolySpline &poly = static_cast<PolySpline &>(dst);
+  poly.positions_ = positions_;
+  poly.radii_ = radii_;
+  poly.tilts_ = tilts_;
 }
 
 int PolySpline::size() const