Metadatas are one of the basic object in Atoms. They are wrapper around basic data types and they hinerit the basic object AtomsCore::Metadata.
The basic Metadata class has function to clone, copy, serialize etc.. to abstract the data type.
These are the basic metadata type that can be used inside Atoms:
- BoolMetadata
- BoolArrayMetadata
- IntMetadata
- IntArrayMetadata
- DoubleMetadata
- DoubleArrayMetadata
- Vector3Metadata
- Vector3ArrayMetadata
- QuaternionMetadata
- QuaternionArrayMetadata
- MatrixMetadata
- MatrixArrayMetadata
- CurveMetadata
- CurveArrayetadata
- MeshMetadata
- MeshArrayMetadata
- ImageMetadata
- PoseMetadata
- SkeletonMetadata
These are container metadata data type:
- MapMetadata
- ArrayMetadata
Creating metadatas
You can create metadata using the normal constructor of each type or you can use the metadata factory. Every metadata type as a unique typeId, it's used to register the metadata inside he metadata factory. Since the serialization code rely on this factory.
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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 metadata. It can store different type od metadata at the same time. It uses strings as key.
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 conunter.
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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
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AtomsPtr<AtomsCore::Vector3Metadata> vecData = mapMeta.getTypedEntry<AtomsCore::Vector3Metadata>("myKey3");
AtomsPtr<Metadata> intData = mapMeta.getEntry("myKey1"); |
ArrayMetadata
The array metadata si similar to the mapmetadata but it store metadata in a vector rather than a map.
Creating a new metadata type
To create a new metadata type you must hinerit the base Metadata class and register the new type to the metadata factory.
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#include <AtomsCore/Metadata/MetadataImpl.h>
class FooData
{
public:
float a;
double b;
char c;
};
typedef AtomsCore::MetadataImpl<FooData> FooMetadata;
template<> bool AtomsCore::MetadataImpl<FooData>::serialise(Archive& outStream) const;
template<> bool AtomsCore::MetadataImpl<FooData>::deserialise(Archive& inStream);
template<> size_t MetadataImpl<FooData>::memSize() const;
template<> void AtomsCore::MetadataImpl<FooData>::toString(std::stringstream& inStream) const;
template class AtomsCore::MetadataImpl<FooData>;
template<> std::string AtomsCore::MetadataImpl<FooData>::staticTypeStr() { return "FooMetadata"; } //!< Bool metadata static type
template<> unsigned int AtomsCore::MetadataImpl<FooData>::staticTypeId() { return 9999999; } //!< This must be a unique id
template<> bool AtomsCore::MetadataImpl<FooData>::serialise(Archive& outStream) const
{
if (outStream.size == 0)
{
outStream.resize(memSize());
}
// the type id must be the first data to serialise
outStream << typeId();
outStream << m_value.a;
outStream << m_value.b;
outStream << m_value.c;
}
template<> bool AtomsCore::MetadataImpl<FooData>::deserialise(Archive& inStream)
{
unsigned int typeIdValue;
inStream >> typeIdValue;
if (typeIdValue != staticTypeId())
return false;
inStream >> m_value.a;
inStream >> m_value.b;
inStream >> m_value.c;
return true;
}
template<> void AtomsCore::MetadataImpl<FooData>::toString(std::stringstream& inStream) const
{
inStream << "FooData: a - " << m_value.a << " b - " << m_value.b << " c - " << m_value.c;
}
template<> size_t TypedArrayMetadata<FooData>::memSize() const
{
return sizeof(unsigned int) + sizeof(float) + sizeof(double) + sizeof(char); //typeid + a + b + c
}
template class AtomsCore::MetadataImpl<FooData>;
void registerMetadata()
{
MetadataFactory& factory = MetadataFactory::instance();
//Register default metadata classes
factory.registerMetadata(FooMetadata::staticTypeStr(), FooMetadata::staticTypeId(), &FooMetadata::creator);
} |