Curves: Port fillet node to the new data-block

This commit ports the fillet curves node to the new curves data-block,
and moves the fillet node implementation to the geometry module to help
separate the implementation from the node.

The changes are similar to the subdivide node or resample node. I've
resused common utilities where it makes sense, though some things like
the iteration over attributes can be generalized further. The node
is now multi-threaded per-curve and inside each curve, and some buffers
are reused per curve to avoid many allocations.

The code is more explicit now, and though there is more boilerplate to
pass around many spans, the more complex logic should be more readable.

Differential Revision: https://developer.blender.org/D15346

1 files changed, 16 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_attribute.hh b/source/blender/blenkernel/BKE_attribute.hh
index 05ab4f1f1f1..108993d91c0 100644
--- a/source/blender/blenkernel/BKE_attribute.hh
+++ b/source/blender/blenkernel/BKE_attribute.hh
@@ -666,6 +666,22 @@ class MutableAttributeAccessor : public AttributeAccessor {
   void remove_anonymous();
 };
 
+struct AttributeTransferData {
+  /* Expect that if an attribute exists, it is stored as a contiguous array internally anyway. */
+  GVArraySpan src;
+  AttributeMetaData meta_data;
+  bke::GSpanAttributeWriter dst;
+};
+/**
+ * Retrieve attribute arrays and writers for attributes that should be transferred between
+ * data-blocks of the same type.
+ */
+Vector<AttributeTransferData> retrieve_attributes_for_transfer(
+    const bke::AttributeAccessor &src_attributes,
+    bke::MutableAttributeAccessor &dst_attributes,
+    eAttrDomainMask domain_mask,
+    const Set<std::string> &skip = {});
+
 bool allow_procedural_attribute_access(StringRef attribute_name);
 extern const char *no_procedural_access_message;