source/blender/blenkernel/BKE_attribute.hh

@@ -929,6 +929,11 @@ void gather_attributes(AttributeAccessor src_attributes,
                        const IndexMask &selection,
                        MutableAttributeAccessor dst_attributes);
 
+/**
+ * Copy attribute values from groups groups defined by \a src_offsets to groups defined by \a
+ * dst_offsets. The group indices are gathered to the result by \a selection. The size of each
+ * source and result group must be the same.
+ */
 void gather_attributes_group_to_group(AttributeAccessor src_attributes,
                                       eAttrDomain domain,
                                       const AnonymousAttributePropagationInfo &propagation_info,

source/blender/blenlib/BLI_offset_indices.hh

@@ -146,6 +146,7 @@ void copy_group_sizes(OffsetIndices<int> offsets, const IndexMask &mask, Mutable
 /** Gather the number of indices in each indexed group to sizes. */
 void gather_group_sizes(OffsetIndices<int> offsets, const IndexMask &mask, MutableSpan<int> sizes);
 
+/** Build new offsets that contains only the groups chosen by \a selection. */
 OffsetIndices<int> gather_selected_offsets(OffsetIndices<int> src_offsets,
                                            const IndexMask &selection,
                                            MutableSpan<int> dst_offsets);