fcb::Feature Class Reference

One decoded feature that OWNS the bytes it points into. More...

#include <fcb/feature.hpp>

Public Member Functions
	Feature ()=default
	Feature (std::shared_ptr< const std::vector< std::uint8_t > > buffer, std::uint64_t byte_offset, std::size_t body_offset)
bool	empty () const
	True for a default-constructed Feature.
std::string	id () const
	The feature's CityJSON id. Empty when empty().
std::size_t	city_object_count () const
	How many CityObjects this feature carries. Zero when empty().
bytes_view	object_attributes (std::size_t i) const
	Raw attribute blob of CityObject i, or empty if it has none.
bool	object_has_attributes (std::size_t i) const
	Whether CityObject i declares an attributes vector at all.
bool	object_extent (std::size_t i, std::array< double, 6 > &out) const
	CityObject i's own bounding box, if it declares one.
bool	object_has_columns (std::size_t i) const
	CityObject i's own column schema, if it declares one.
std::vector< ColumnInfo >	object_columns (std::size_t i) const
std::string	object_id (std::size_t i) const
	CityObject i's id.
std::uint64_t	byte_offset () const
	Byte offset of this feature RELATIVE to the start of the features section, matching the offsets stored in the R-tree leaves.
const ::CityFeature *	raw () const
	The generated CityFeature table behind this Feature.

Friends
struct	detail::FeatureAccess

Detailed Description

One decoded feature that OWNS the bytes it points into.

Copying a Feature copies a shared_ptr, not the buffer, so features stay valid after the iterator and reader that produced them are destroyed.

The generated ::CityFeature pointer is deliberately not public: a caller could retain it past this object's destruction. Internal decoders reach it via detail::FeatureAccess.

Definition at line 33 of file feature.hpp.

Constructor & Destructor Documentation

Feature() [1/2]

fcb::Feature::Feature ( )

default

Feature() [2/2]

fcb::Feature::Feature	(	std::shared_ptr< const std::vector< std::uint8_t > >	buffer,
		std::uint64_t	byte_offset,
		std::size_t	body_offset
	)

Definition at line 22 of file reader.cpp.

Member Function Documentation

byte_offset()

std::uint64_t fcb::Feature::byte_offset ( ) const

inline

Byte offset of this feature RELATIVE to the start of the features section, matching the offsets stored in the R-tree leaves.

Definition at line 81 of file feature.hpp.

Referenced by fcb::FcbReader::select_attr().

city_object_count()

std::size_t fcb::Feature::city_object_count

(

)

const

How many CityObjects this feature carries. Zero when empty().

Definition at line 111 of file reader.cpp.

Referenced by fcb::FcbReader::select_attr(), and fcb::to_cityjson_feature().

empty()

bool fcb::Feature::empty ( ) const

inline

True for a default-constructed Feature.

Definition at line 40 of file feature.hpp.

id()

std::string fcb::Feature::id

(

)

const

The feature's CityJSON id. Empty when empty().

Definition at line 34 of file reader.cpp.

Referenced by fcb::to_cityjson_feature().

object_attributes()

bytes_view fcb::Feature::object_attributes

(

std::size_t

i

)

const

Raw attribute blob of CityObject i, or empty if it has none.

Objects commonly differ: in the 3DBAG data a Building parent carries no attributes while its BuildingPart child carries them all.

Definition at line 51 of file reader.cpp.

Referenced by fcb::FcbReader::select_attr(), and fcb::to_cityjson_feature().

object_columns()

std::vector< ColumnInfo > fcb::Feature::object_columns

(

std::size_t

i

)

const

Definition at line 85 of file reader.cpp.

References fcb::ColumnInfo::index.

Referenced by fcb::FcbReader::select_attr(), and fcb::to_cityjson_feature().

object_extent()

bool fcb::Feature::object_extent	(	std::size_t	i,
		std::array< double, 6 > &	out
	)		const

CityObject i's own bounding box, if it declares one.

Returns false when absent.

Definition at line 64 of file reader.cpp.

Referenced by fcb::to_cityjson_feature().

object_has_attributes()

bool fcb::Feature::object_has_attributes

(

std::size_t

i

)

const

Whether CityObject i declares an attributes vector at all.

Distinct from object_attributes(i).empty(): a present-but-empty vector is emitted as "attributes": {}, an absent one is omitted.

Definition at line 59 of file reader.cpp.

Referenced by fcb::to_cityjson_feature().

object_has_columns()

bool fcb::Feature::object_has_columns

(

std::size_t

i

)

const

CityObject i's own column schema, if it declares one.

feature.fbs documents CityObject.columns as overriding the header schema when set. Decoding with the wrong schema silently desynchronises the blob – records are not self-delimiting – so this must be consulted before decode_attributes(). Empty means "use the header's columns". Whether CityObject i DECLARES its own column schema. FlatBuffers presence is what selects the override, not vector non-emptiness: an explicitly empty schema must not silently fall back to the header's.

Definition at line 80 of file reader.cpp.

Referenced by fcb::FcbReader::select_attr(), and fcb::to_cityjson_feature().

object_id()

std::string fcb::Feature::object_id

(

std::size_t

i

)

const

CityObject i's id.

Definition at line 104 of file reader.cpp.

Referenced by fcb::to_cityjson_feature().

raw()

const ::CityFeature * fcb::Feature::raw

(

)

const

The generated CityFeature table behind this Feature.

This is the supported way to reach the ENCODED geometry – the format's own five count arrays (solids/shells/surfaces/strings plus the flat boundaries index list) and the quantised vertices they index into – for analysis that does not want CityJSON built first. Nothing has to be nested or allocated to compute over them. See examples/geometry_analysis.cpp.

NESTING DEPTH COMES FROM Geometry::type(), NEVER FROM THE ARRAYS: a Solid with one shell and a MultiSolid with one solid flatten to byte-identical arrays. Inferring depth from which array is populated is upstream finding #8.

Include <fcb/generated/feature_generated.h> for the complete type; this header only forward-declares it.

Definition at line 26 of file reader.cpp.

Referenced by fcb::detail::FeatureAccess::get().

Friends And Related Symbol Documentation

detail::FeatureAccess

friend struct detail::FeatureAccess

friend

Definition at line 102 of file feature.hpp.

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The documentation for this class was generated from the following files:

• include/fcb/feature.hpp
• src/reader.cpp