API Reference — dna/Writer

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class DNAAPI Writer : public RBFBehaviorWriter, public GeometryWriter, public MachineLearnedBehaviorExtWriter, public JointBehaviorMetadataWriter, public TwistSwingBehaviorWriter

Abstract unified write interface for all DNA data layers. Use this as the base type when you need to write a complete DNA asset — it combines geometry, behavior, machine-learned behavior, RBF, joint metadata, and twist/swing writing into a single entry point.

When to use this

Reach for Writer when you need to mutate or construct a DNA asset. Use setFrom to bulk-copy an entire existing asset from a Reader — optionally restricting which layers are transferred via DataLayer. Note that the layer hierarchy cannot be written selectively at the class level; the unified interface is intentional.

Example

// Obtain a Writer instance (e.g., from BinaryStreamWriter factory)
dna::Writer* writer = dna::BinaryStreamWriter::create(stream, memRes);
const dna::Reader* reader = dna::BinaryStreamReader::create(inputStream, memRes);

// Copy all layers, preserving any unknown data
writer->setFrom(reader, dna::DataLayer::All, dna::UnknownLayerPolicy::Preserve);

// Copy only geometry, discarding unrecognized layers
writer->setFrom(reader, dna::DataLayer::Geometry, dna::UnknownLayerPolicy::Discard);

Parameters

Name	Type	Description
source	const Reader*	required — the DNA Reader to copy data from
layer	DataLayer	optional — limits which layers are transferred; defaults to DataLayer::All
policy	UnknownLayerPolicy	optional — whether unrecognized layers are preserved or discarded; defaults to UnknownLayerPolicy::Preserve
memRes	MemoryResource*	optional — memory resource for temporary allocations during the copy; defaults to nullptr

Watch out for

• The Writer class intentionally cannot write only specific layers — the unified interface mirrors the Reader hierarchy by design. Use DataLayer in setFrom to control which layers are read from source, not which are written.
• setFrom is implemented in the abstract base class itself and calls every getter on source then every matching setter on this. For large DNA assets, pass a MemoryResource to avoid heap fragmentation during the copy.