Working with metadata (AtomsUnreal)

Metadatas are one of the basic entities in Atoms. They wrap basic data types and inherit the basic object AtomsCore::Metadata.

The basic Metadata class has functions to clone, copy, serialize etc.

These are the basic metadata type that can be used inside Atoms:

BoolMetadata
BoolArrayMetadata
IntMetadata
IntArrayMetadata
DoubleMetadata
DoubleArrayMetadata
Vector3Metadata
Vector3ArrayMetadata
EulerMetadata
EulerArrayMetadata
QuaternionMetadata
QuaternionArrayMetadata
MatrixMetadata
MatrixArrayMetadata
CurveMetadata
CurveArrayetadata
MeshMetadata
MeshArrayMetadata
ImageMetadata
PoseMetadata
SkeletonMetadata

These are container metadata types:

MapMetadata
ArrayMetadata

Unreal Specific metadata:

UnrealObjectMetadata (value is a TWeakObjectPtr - declared inside AtomsObjectMetadata.h)
UnrealObjectArrayMetadata (Array of TWeakObjectPtr - declared inside AtomsObjectMetadata.h)

Creating metadatas

You can create metadatas using the constructor of each type or you can use the metadata factory. Every metadata type has a unique typeId, it's used to register the metadata inside the metadata factory. Since the serialization code relies on this factory.

AtomsCore::IntMetadata intMeta(5);
AtomsCore::DoubleMetadata doubleMeta(654.4);

AtomsCore::MetadataFactory& factory = AtomsCore::MetadataFactory::instance();
AtomsPtr<AtomsCore::Metadata> data = factory.createMetadata(AtomsCore::Vector3Metadata::staticTypeId());

MapMetada

The MapMetadata is a map container for metadatas. It can store different metadata types at the same time. It uses strings as keys.

To insert data inside a MapMetadata use the addEntry function. This function can clone the input metadata or store directly the input smart pointer, increasing the reference counter.

AtomsCore::MapMetadata mapMeta;
// Insert element cloning the data
mapMeta.addEnetry("myKey1", &AtomsCore::IntMetadata(4));

AtomsPtr<AtomsCore::DoubleMetadata> doubleMeta(new AtomsCore::DoubleMetadata(5.7));
// Insert element cloning the data
mapMeta.addEntry("myKey2", std::static_pointer_cast<AtomsCore::Metadata>(doubleMeta), true);

AtomsPtr<AtomsCore::Vector3Metadata> vecMeta(new AtomsCore::Vector3Metadata(AtomsCore::Vector3(1,0,0));
// Insert element without cloning, copying the smart pointer and increasing the reference counter
mapMeta.addEntry("myKey3", std::static_pointer_cast<AtomsCore::Metadata>(vecMeta), false);

To get an entry from the map, use the getEntry or getTypedEntry function

AtomsPtr<AtomsCore::Vector3Metadata> vecData = mapMeta.getTypedEntry<AtomsCore::Vector3Metadata>("myKey3");
AtomsPtr<Metadata> intData = mapMeta.getEntry("myKey1");

ArrayMetadata

The array metadata is similar to the MapMetadata but it stores metadata in a vector rather than a map.

Creating a new metadata type

To create a new metadata type you must inherit the base Metadata class and register the new type in the metadata factory.