Implements a light-weight self-contained VDB data-structure in a single file! In other words, this is a significantly watered-down version of the OpenVDB implementation, with few dependencies - so a one-stop-shop for a minimalistic VDB data structure that run on most platforms! More...

#include <nanovdb/util/Util.h>
#include <nanovdb/math/Math.h>

Classes
class	ValueIndex
	Dummy type for a voxel whose value equals an offset into an external value array. More...

class	ValueOnIndex
	Dummy type for a voxel whose value equals an offset into an external value array of active values. More...

class	ValueIndexMask
	Like `ValueIndex` but with a mutable mask. More...

class	ValueOnIndexMask
	Like `ValueOnIndex` but with a mutable mask. More...

class	ValueMask
	Dummy type for a voxel whose value equals its binary active state. More...

class	Half
	Dummy type for a 16 bit floating point values (placeholder for IEEE 754 Half) More...

class	Fp4
	Dummy type for a 4bit quantization of float point values. More...

class	Fp8
	Dummy type for a 8bit quantization of float point values. More...

class	Fp16
	Dummy type for a 16bit quantization of float point values. More...

class	FpN
	Dummy type for a variable bit quantization of floating point values. More...

class	Point
	Dummy type for indexing points into voxels. More...

struct	BuildTraits< T >
	Define static boolean tests for template build types. More...

struct	BuildToValueMap< T >
	Maps one type (e.g. the build types above) to other (actual) types. More...

struct	BuildToValueMap< ValueIndex >

struct	BuildToValueMap< ValueOnIndex >

struct	BuildToValueMap< ValueIndexMask >

struct	BuildToValueMap< ValueOnIndexMask >

struct	BuildToValueMap< ValueMask >

struct	BuildToValueMap< Half >

struct	BuildToValueMap< Fp4 >

struct	BuildToValueMap< Fp8 >

struct	BuildToValueMap< Fp16 >

struct	BuildToValueMap< FpN >

struct	BuildToValueMap< Point >

class	Version
	Bit-compacted representation of all three version numbers. More...

struct	TensorTraits< T, Rank >

struct	TensorTraits< T, 0 >

struct	TensorTraits< T, 1 >

struct	FloatTraits< T, int >

struct	FloatTraits< T, 8 >

struct	FloatTraits< bool, 1 >

struct	FloatTraits< ValueIndex, 1 >

struct	FloatTraits< ValueIndexMask, 1 >

struct	FloatTraits< ValueOnIndex, 1 >

struct	FloatTraits< ValueOnIndexMask, 1 >

struct	FloatTraits< ValueMask, 1 >

struct	FloatTraits< Point, 1 >

struct	BitArray< N >

struct	BitArray< 8 >

struct	BitArray< 16 >

struct	BitArray< 32 >

struct	BitArray< 64 >

class	BitFlags< N >

class	Mask< LOG2DIM >
	Bit-mask to encode active states and facilitate sequential iterators and a fast codec for I/O compression. More...

class	Mask< LOG2DIM >::Iterator< On >

class	Mask< LOG2DIM >::DenseIterator

struct	Map
	Defines an affine transform and its inverse represented as a 3x3 matrix and a vec3 translation. More...

struct	GridBlindMetaData

struct	NodeTrait< GridOrTreeOrRootT, LEVEL >
	Struct to derive node type from its level in a given grid, tree or root while preserving constness. More...

struct	NodeTrait< GridOrTreeOrRootT, 0 >

struct	NodeTrait< const GridOrTreeOrRootT, 0 >

struct	NodeTrait< GridOrTreeOrRootT, 1 >

struct	NodeTrait< const GridOrTreeOrRootT, 1 >

struct	NodeTrait< GridOrTreeOrRootT, 2 >

struct	NodeTrait< const GridOrTreeOrRootT, 2 >

struct	NodeTrait< GridOrTreeOrRootT, 3 >

struct	NodeTrait< const GridOrTreeOrRootT, 3 >

struct	GetValue< BuildT >
	Implements Tree::getValue(math::Coord), i.e. return the value associated with a specific coordinate `ijk`. More...

struct	SetValue< BuildT >

struct	SetVoxel< BuildT >

struct	GetState< BuildT >
	Implements Tree::isActive(math::Coord) More...

struct	GetDim< BuildT >
	Implements Tree::getDim(math::Coord) More...

struct	GetLeaf< BuildT >
	Return the pointer to the leaf node that contains math::Coord. Implements Tree::probeLeaf(math::Coord) More...

struct	ProbeValue< BuildT >
	Implements Tree::probeLeaf(math::Coord) More...

struct	GetNodeInfo< BuildT >
	Implements Tree::getNodeInfo(math::Coord) More...

class	Checksum
	Class that encapsulates two CRC32 checksums, one for the Grid, Tree and Root node meta data and one for the remaining grid nodes. More...

struct	GridData
	Struct with all the member data of the Grid (useful during serialization of an openvdb grid) More...

class	ReadAccessor< BuildT, LEVEL0, LEVEL1, LEVEL2 >

class	Grid< TreeT >
	Highest level of the data structure. Contains a tree and a world->index transform (that currently only supports uniform scaling and translation). More...

struct	TreeData

struct	GridTree< GridT >
	defines a tree type from a grid type while preserving constness More...

struct	GridTree< const GridT >

class	Tree< RootT >
	VDB Tree, which is a thin wrapper around a RootNode. More...

struct	RootData< ChildT >
	Struct with all the member data of the RootNode (useful during serialization of an openvdb RootNode) More...

struct	RootData< ChildT >::Tile

class	RootNode< ChildT >
	Top-most node of the VDB tree structure. More...

class	RootNode< ChildT >::BaseIter< RootT >

class	RootNode< ChildT >::ChildIter< RootT >

class	RootNode< ChildT >::ValueIter< RootT >

class	RootNode< ChildT >::ValueOnIter< RootT >

class	RootNode< ChildT >::DenseIter< RootT >

struct	InternalData< ChildT, LOG2DIM >
	Struct with all the member data of the InternalNode (useful during serialization of an openvdb InternalNode) More...

union	InternalData< ChildT, LOG2DIM >::Tile

class	InternalNode< ChildT, Log2Dim >
	Internal nodes of a VDB tree. More...

class	InternalNode< ChildT, Log2Dim >::ChildIter< ParentT >
	Visits child nodes of this node only. More...

class	InternalNode< ChildT, Log2Dim >::ValueIterator
	Visits all tile values in this node, i.e. both inactive and active tiles. More...

class	InternalNode< ChildT, Log2Dim >::ValueOnIterator
	Visits active tile values of this node only. More...

class	InternalNode< ChildT, Log2Dim >::DenseIterator
	Visits all tile values and child nodes of this node. More...

struct	LeafData< ValueT, CoordT, MaskT, LOG2DIM >
	Stuct with all the member data of the LeafNode (useful during serialization of an openvdb LeafNode) More...

struct	LeafFnBase< CoordT, MaskT, LOG2DIM >
	Base-class for quantized float leaf nodes. More...

struct	LeafData< Fp4, CoordT, MaskT, LOG2DIM >
	Stuct with all the member data of the LeafNode (useful during serialization of an openvdb LeafNode) More...

struct	LeafData< Fp8, CoordT, MaskT, LOG2DIM >

struct	LeafData< Fp16, CoordT, MaskT, LOG2DIM >

struct	LeafData< FpN, CoordT, MaskT, LOG2DIM >

struct	LeafData< bool, CoordT, MaskT, LOG2DIM >

struct	LeafData< ValueMask, CoordT, MaskT, LOG2DIM >

struct	LeafIndexBase< CoordT, MaskT, LOG2DIM >

struct	LeafData< ValueIndex, CoordT, MaskT, LOG2DIM >

struct	LeafData< ValueOnIndex, CoordT, MaskT, LOG2DIM >

struct	LeafData< ValueIndexMask, CoordT, MaskT, LOG2DIM >

struct	LeafData< ValueOnIndexMask, CoordT, MaskT, LOG2DIM >

struct	LeafData< Point, CoordT, MaskT, LOG2DIM >

class	LeafNode< BuildT, CoordT, MaskT, Log2Dim >
	Leaf nodes of the VDB tree. (defaults to 8x8x8 = 512 voxels) More...

struct	LeafNode< BuildT, CoordT, MaskT, Log2Dim >::ChildNodeType

class	LeafNode< BuildT, CoordT, MaskT, Log2Dim >::ValueOnIterator
	Visits all active values in a leaf node. More...

class	LeafNode< BuildT, CoordT, MaskT, Log2Dim >::ValueOffIterator
	Visits all inactive values in a leaf node. More...

class	LeafNode< BuildT, CoordT, MaskT, Log2Dim >::ValueIterator
	Visits all values in a leaf node, i.e. both active and inactive values. More...

struct	NanoNode< BuildT, LEVEL >
	Trait to map from LEVEL to node type. More...

struct	NanoNode< BuildT, 0 >

struct	NanoNode< BuildT, 1 >

struct	NanoNode< BuildT, 2 >

struct	NanoNode< BuildT, 3 >

class	ReadAccessor< BuildT,-1,-1,-1 >
	A read-only value accessor with three levels of node caching. This allows for inverse tree traversal during lookup, which is on average significantly faster than calling the equivalent method on the tree (i.e. top-down traversal). More...

class	ReadAccessor< BuildT, LEVEL0,-1,-1 >
	Node caching at a single tree level. More...

class	ReadAccessor< BuildT, LEVEL0, LEVEL1,-1 >

class	ReadAccessor< BuildT, 0, 1, 2 >
	Node caching at all (three) tree levels. More...

class	GridMetaData
	This is a convenient class that allows for access to grid meta-data that are independent of the value type of a grid. That is, this class can be used to get information about a grid without actually knowing its ValueType. More...

class	PointAccessor< AttT, BuildT >
	Class to access points at a specific voxel location. More...

class	PointAccessor< AttT, Point >

class	ChannelAccessor< ChannelT, IndexT >
	Class to access values in channels at a specific voxel location. More...

struct	FileHeader
	Data encoded at the head of each segment of a file or stream. More...

struct	FileMetaData

struct	GetValue< BuildT >
	Implements Tree::getValue(math::Coord), i.e. return the value associated with a specific coordinate `ijk`. More...

struct	SetValue< BuildT >

struct	SetVoxel< BuildT >

struct	GetState< BuildT >
	Implements Tree::isActive(math::Coord) More...

struct	GetDim< BuildT >
	Implements Tree::getDim(math::Coord) More...

struct	GetLeaf< BuildT >
	Return the pointer to the leaf node that contains math::Coord. Implements Tree::probeLeaf(math::Coord) More...

struct	GetLower< BuildT >
	Return point to the lower internal node where math::Coord maps to one of its values, i.e. terminates. More...

struct	GetUpper< BuildT >
	Return point to the upper internal node where math::Coord maps to one of its values, i.e. terminates. More...

struct	ProbeValue< BuildT >
	Implements Tree::probeLeaf(math::Coord) More...

struct	GetNodeInfo< BuildT >
	Implements Tree::getNodeInfo(math::Coord) More...

struct	GetNodeInfo< BuildT >::NodeInfo

Namespaces
	nanovdb

	nanovdb::io

Macros
#define	NANOVDB_DATA_ALIGNMENT 32

#define	NANOVDB_MAGIC_NUMB 0x304244566f6e614eUL

#define	NANOVDB_MAGIC_GRID 0x314244566f6e614eUL

#define	NANOVDB_MAGIC_FILE 0x324244566f6e614eUL

#define	NANOVDB_MAGIC_NODE 0x334244566f6e614eUL

#define	NANOVDB_MAGIC_FRAG 0x344244566f6e614eUL

#define	NANOVDB_MAGIC_MASK 0x00FFFFFFFFFFFFFFUL

#define	NANOVDB_MAJOR_VERSION_NUMBER 32

#define	NANOVDB_MINOR_VERSION_NUMBER 7

#define	NANOVDB_PATCH_VERSION_NUMBER 0

#define	TBB_SUPPRESS_DEPRECATED_MESSAGES 1

#define	NANOVDB_USE_SINGLE_ROOT_KEY

#define	NANOVDB_NEW_ACCESSOR_METHODS

#define	NANOVDB_FPN_BRANCHLESS

#define	NANOVDB_ALIGN(n) alignas(n)

Typedefs
template<typename BuildT >
using	DefaultReadAccessor = ReadAccessor< BuildT, 0, 1, 2 >

template<typename BuildT >
using	NanoLeaf = LeafNode< BuildT, Coord, Mask, 3 >
	Template specializations to the default configuration used in OpenVDB: Root -> 32^3 -> 16^3 -> 8^3. More...

template<typename BuildT >
using	NanoLower = InternalNode< NanoLeaf< BuildT >, 4 >

template<typename BuildT >
using	NanoUpper = InternalNode< NanoLower< BuildT >, 5 >

template<typename BuildT >
using	NanoRoot = RootNode< NanoUpper< BuildT >>

template<typename BuildT >
using	NanoTree = Tree< NanoRoot< BuildT >>

template<typename BuildT >
using	NanoGrid = Grid< NanoTree< BuildT >>

using	FloatTree = NanoTree< float >

using	Fp4Tree = NanoTree< Fp4 >

using	Fp8Tree = NanoTree< Fp8 >

using	Fp16Tree = NanoTree< Fp16 >

using	FpNTree = NanoTree< FpN >

using	DoubleTree = NanoTree< double >

using	Int32Tree = NanoTree< int32_t >

using	UInt32Tree = NanoTree< uint32_t >

using	Int64Tree = NanoTree< int64_t >

using	Vec3fTree = NanoTree< Vec3f >

using	Vec3dTree = NanoTree< Vec3d >

using	Vec4fTree = NanoTree< Vec4f >

using	Vec4dTree = NanoTree< Vec4d >

using	Vec3ITree = NanoTree< Vec3i >

using	MaskTree = NanoTree< ValueMask >

using	BoolTree = NanoTree< bool >

using	IndexTree = NanoTree< ValueIndex >

using	OnIndexTree = NanoTree< ValueOnIndex >

using	IndexMaskTree = NanoTree< ValueIndexMask >

using	OnIndexMaskTree = NanoTree< ValueOnIndexMask >

using	FloatGrid = Grid< FloatTree >

using	Fp4Grid = Grid< Fp4Tree >

using	Fp8Grid = Grid< Fp8Tree >

using	Fp16Grid = Grid< Fp16Tree >

using	FpNGrid = Grid< FpNTree >

using	DoubleGrid = Grid< DoubleTree >

using	Int32Grid = Grid< Int32Tree >

using	UInt32Grid = Grid< UInt32Tree >

using	Int64Grid = Grid< Int64Tree >

using	Vec3fGrid = Grid< Vec3fTree >

using	Vec3dGrid = Grid< Vec3dTree >

using	Vec4fGrid = Grid< Vec4fTree >

using	Vec4dGrid = Grid< Vec4dTree >

using	Vec3IGrid = Grid< Vec3ITree >

using	MaskGrid = Grid< MaskTree >

using	BoolGrid = Grid< BoolTree >

using	PointGrid = Grid< Point >

using	IndexGrid = Grid< IndexTree >

using	OnIndexGrid = Grid< OnIndexTree >

using	IndexMaskGrid = Grid< IndexMaskTree >

using	OnIndexMaskGrid = Grid< OnIndexMaskTree >

Enumerations
enum	GridType : uint32_t { Unknown = 0, Float = 1, Double = 2, Int16 = 3, Int32 = 4, Int64 = 5, Vec3f = 6, Vec3d = 7, Mask = 8, Half = 9, UInt32 = 10, Boolean = 11, RGBA8 = 12, Fp4 = 13, Fp8 = 14, Fp16 = 15, FpN = 16, Vec4f = 17, Vec4d = 18, Index = 19, OnIndex = 20, IndexMask = 21, OnIndexMask = 22, PointIndex = 23, Vec3u8 = 24, Vec3u16 = 25, UInt8 = 26, End = 27, StrLen = End + 12 }
	List of types that are currently supported by NanoVDB. More...

enum	GridClass : uint32_t { Unknown = 0, LevelSet = 1, FogVolume = 2, Staggered = 3, PointIndex = 4, PointData = 5, Topology = 6, VoxelVolume = 7, IndexGrid = 8, TensorGrid = 9, End = 10, StrLen = End + 7 }
	Classes (superset of OpenVDB) that are currently supported by NanoVDB. More...

enum	GridFlags : uint32_t { HasLongGridName = 1 << 0, HasBBox = 1 << 1, HasMinMax = 1 << 2, HasAverage = 1 << 3, HasStdDeviation = 1 << 4, IsBreadthFirst = 1 << 5, End = 1 << 6, StrLen = End + 23 }
	Grid flags which indicate what extra information is present in the grid buffer. More...

enum	MagicType : uint32_t { Unknown = 0, OpenVDB = 1, NanoVDB = 2, NanoGrid = 3, NanoFile = 4, NanoNode = 5, NanoFrag = 6, End = 7, StrLen = End + 25 }
	Enums used to identify magic numbers recognized by NanoVDB. More...

enum	PointType : uint32_t { Disable = 0, PointID = 1, World64 = 2, World32 = 3, Grid64 = 4, Grid32 = 5, Voxel32 = 6, Voxel16 = 7, Voxel8 = 8, Default = 9, End =10 }

enum	GridBlindDataClass : uint32_t { Unknown = 0, IndexArray = 1, AttributeArray = 2, GridName = 3, ChannelArray = 4, End = 5 }
	Blind-data Classes that are currently supported by NanoVDB. More...

enum	GridBlindDataSemantic : uint32_t { Unknown = 0, PointPosition = 1, PointColor = 2, PointNormal = 3, PointRadius = 4, PointVelocity = 5, PointId = 6, WorldCoords = 7, GridCoords = 8, VoxelCoords = 9, End = 10 }
	Blind-data Semantics that are currently understood by NanoVDB. More...

enum	CheckMode : uint32_t { Disable = 0, Empty = 0, Half = 1, Partial = 1, Default = 1, Full = 2, End = 3, StrLen = 9 + End }
	List of different modes for computing for a checksum. More...

enum	Codec : uint16_t { NONE = 0, ZIP = 1, BLOSC = 2, End = 3, StrLen = 6 + End }
	Define compression codecs. More...

Functions
template<class EnumT >
__hostdev__ constexpr uint32_t	strlen ()
	return the number of characters (including null termination) required to convert enum type to a string More...

__hostdev__ char *	toStr (char *dst, GridType gridType)
	Maps a GridType to a c-string. More...

__hostdev__ char *	toStr (char *dst, GridClass gridClass)
	Retuns a c-string used to describe a GridClass. More...

__hostdev__ const char *	toStr (char *dst, GridFlags gridFlags)
	Retuns a c-string used to describe a GridFlags. More...

__hostdev__ MagicType	toMagic (uint64_t magic)
	maps 64 bits of magic number to enum More...

__hostdev__ char *	toStr (char *dst, MagicType magic)
	print 64-bit magic number to string More...

static __hostdev__ bool	isAligned (const void *p)
	return true if the specified pointer is 32 byte aligned More...

static __hostdev__ uint64_t	alignmentPadding (const void *p)
	return the smallest number of bytes that when added to the specified pointer results in a 32 byte aligned pointer. More...

template<typename T >
static __hostdev__ T *	alignPtr (T *p)
	offset the specified pointer so it is 32 byte aligned. Works with both const and non-const pointers. More...

__hostdev__ bool	isFloatingPoint (GridType gridType)
	return true if the GridType maps to a floating point type More...

__hostdev__ bool	isFloatingPointVector (GridType gridType)
	return true if the GridType maps to a floating point vec3. More...

__hostdev__ bool	isInteger (GridType gridType)
	Return true if the GridType maps to a POD integer type. More...

__hostdev__ bool	isIndex (GridType gridType)
	Return true if the GridType maps to a special index type (not a POD integer type). More...

__hostdev__ bool	isValid (GridType gridType, GridClass gridClass)
	return true if the combination of GridType and GridClass is valid. More...

__hostdev__ bool	isValid (const GridBlindDataClass &blindClass, const GridBlindDataSemantic &blindSemantics, const GridType &blindType)
	return true if the combination of GridBlindDataClass, GridBlindDataSemantic and GridType is valid. More...

__hostdev__ char *	toStr (char *dst, const Version &v)
	print the verion number to a c-string More...

template<typename BuildT >
__hostdev__ GridType	toGridType ()
	Maps from a templated build type to a GridType enum. More...

template<typename BuildT >
__hostdev__ GridType	mapToGridType ()

template<typename BuildT >
__hostdev__ GridClass	toGridClass (GridClass defaultClass=GridClass::Unknown)
	Maps from a templated build type to a GridClass enum. More...

template<typename BuildT >
__hostdev__ GridClass	mapToGridClass (GridClass defaultClass=GridClass::Unknown)

__hostdev__ char *	toStr (char *dst, CheckMode mode)
	Prints CheckMode enum to a c-string. More...

__hostdev__ CheckMode	toCheckMode (const Checksum &checksum)
	Maps 64 bit checksum to CheckMode enum. More...

template<typename OpT , typename GridDataT , typename... ArgsT>
auto	callNanoGrid (GridDataT *gridData, ArgsT &&...args)
	Below is an example of the struct used for generic programming with callNanoGrid. More...

template<int LEVEL0 = -1, int LEVEL1 = -1, int LEVEL2 = -1, typename ValueT = float>
ReadAccessor< ValueT, LEVEL0, LEVEL1, LEVEL2 >	createAccessor (const NanoGrid< ValueT > &grid)
	Free-standing function for convenient creation of a ReadAccessor with optional and customizable node caching. More...

template<int LEVEL0 = -1, int LEVEL1 = -1, int LEVEL2 = -1, typename ValueT = float>
ReadAccessor< ValueT, LEVEL0, LEVEL1, LEVEL2 >	createAccessor (const NanoTree< ValueT > &tree)

template<int LEVEL0 = -1, int LEVEL1 = -1, int LEVEL2 = -1, typename ValueT = float>
ReadAccessor< ValueT, LEVEL0, LEVEL1, LEVEL2 >	createAccessor (const NanoRoot< ValueT > &root)

__hostdev__ const char *	toStr (char *dst, Codec codec)

__hostdev__ Codec	toCodec (const char *str)

template<typename StreamT >
void	writeUncompressedGrid (StreamT &os, const GridData *gridData, bool raw=false)
	This is a standalone alternative to io::writeGrid(...,Codec::NONE) defined in util/IO.h Unlike the latter this function has no dependencies at all, not even NanoVDB.h, so it also works if client code only includes PNanoVDB.h! More...

template<typename GridHandleT , template< typename... > class VecT>
void	writeUncompressedGrids (const char *fileName, const VecT< GridHandleT > &handles, bool raw=false)
	write multiple NanoVDB grids to a single file, without compression. More...

template<typename GridHandleT , typename StreamT , template< typename... > class VecT>
VecT< GridHandleT >	readUncompressedGrids (StreamT &is, const typename GridHandleT::BufferType &pool=typename GridHandleT::BufferType())
	read all uncompressed grids from a stream and return their handles. More...

template<typename GridHandleT , template< typename... > class VecT>
VecT< GridHandleT >	readUncompressedGrids (const char *fileName, const typename GridHandleT::BufferType &buffer=typename GridHandleT::BufferType())
	Read a multiple un-compressed NanoVDB grids from a file and return them as a vector. More...

Detailed Description

Implements a light-weight self-contained VDB data-structure in a single file! In other words, this is a significantly watered-down version of the OpenVDB implementation, with few dependencies - so a one-stop-shop for a minimalistic VDB data structure that run on most platforms!

Author: Ken Museth

Date: January 8, 2020

Note: It is important to note that NanoVDB (by design) is a read-only sparse GPU (and CPU) friendly data structure intended for applications like rendering and collision detection. As such it obviously lacks a lot of the functionality and features of OpenVDB grids. NanoVDB is essentially a compact linearized (or serialized) representation of an OpenVDB tree with getValue methods only. For best performance use the ReadAccessor::getValue method as opposed to the Tree::getValue method. Note that since a ReadAccessor caches previous access patterns it is by design not thread-safe, so use one instantiation per thread (it is very light-weight). Also, it is not safe to copy accessors between the GPU and CPU! In fact, client code should only interface with the API of the Grid class (all other nodes of the NanoVDB data structure can safely be ignored by most client codes)!

Warning: NanoVDB grids can only be constructed via tools like createNanoGrid or the GridBuilder. This explains why none of the grid nodes defined below have public constructors or destructors.

Please see the following paper for more details on the data structure: K. Museth, “VDB: High-Resolution Sparse Volumes with Dynamic Topology”, ACM Transactions on Graphics 32(3), 2013, which can be found here: http://www.museth.org/Ken/Publications_files/Museth_TOG13.pdf

NanoVDB was first published there: https://dl.acm.org/doi/fullHtml/10.1145/3450623.3464653

Overview: This file implements the following fundamental class that when combined forms the backbone of the VDB tree data structure:

Coord- a signed integer coordinate Vec3 - a 3D vector Vec4 - a 4D vector BBox - a bounding box Mask - a bitmask essential to the non-root tree nodes Map - an affine coordinate transformation Grid - contains a Tree and a map for world<->index transformations. Use this class as the main API with client code! Tree - contains a RootNode and getValue methods that should only be used for debugging RootNode - the top-level node of the VDB data structure InternalNode - the internal nodes of the VDB data structure LeafNode - the lowest level tree nodes that encode voxel values and state ReadAccessor - implements accelerated random access operations

Semantics: A VDB data structure encodes values and (binary) states associated with signed integer coordinates. Values encoded at the leaf node level are denoted voxel values, and values associated with other tree nodes are referred to as tile values, which by design cover a larger coordinate index domain.

Memory layout:

It's important to emphasize that all the grid data (defined below) are explicitly 32 byte aligned, which implies that any memory buffer that contains a NanoVDB grid must also be at 32 byte aligned. That is, the memory address of the beginning of a buffer (see ascii diagram below) must be divisible by 32, i.e. uintptr_t(&buffer)%32 == 0! If this is not the case, the C++ standard says the behaviour is undefined! Normally this is not a concerns on GPUs, because they use 256 byte aligned allocations, but the same cannot be said about the CPU.

GridData is always at the very beginning of the buffer immediately followed by TreeData! The remaining nodes and blind-data are allowed to be scattered throughout the buffer, though in practice they are arranged as:

GridData: 672 bytes (e.g. magic, checksum, major, flags, index, count, size, name, map, world bbox, voxel size, class, type, offset, count)

TreeData: 64 bytes (node counts and byte offsets)

... optional padding ...

RootData: size depends on ValueType (index bbox, voxel count, tile count, min/max/avg/standard deviation)

Array of: RootData::Tile

... optional padding ...

Array of: Upper InternalNodes of size 32^3: bbox, two bit masks, 32768 tile values, and min/max/avg/standard deviation values

... optional padding ...

Array of: Lower InternalNodes of size 16^3: bbox, two bit masks, 4096 tile values, and min/max/avg/standard deviation values

... optional padding ...

Array of: LeafNodes of size 8^3: bbox, bit masks, 512 voxel values, and min/max/avg/standard deviation values

Notation: "]---[" implies it has optional padding, and "][" implies zero padding

[GridData(672B)][TreeData(64B)]—[RootData][N x Root::Tile]—[InternalData<5>]—[InternalData<4>]—[LeafData<3>]—[BLINDMETA...]—[BLIND0]—[BLIND1]—etc. ^ ^ ^ ^ ^ ^ | | | | | | +– Start of 32B aligned buffer | | | | +– Node0::DataType* leafData GridType::DataType* gridData | | | | | | | +– Node1::DataType* lowerData RootType::DataType* rootData –+ | | | +– Node2::DataType* upperData | +– RootType::DataType::Tile* tile

Macro Definition Documentation

#define NANOVDB_ALIGN ( n ) alignas(n)

#define NANOVDB_DATA_ALIGNMENT 32

#define NANOVDB_FPN_BRANCHLESS

#define NANOVDB_MAGIC_FILE 0x324244566f6e614eUL

#define NANOVDB_MAGIC_FRAG 0x344244566f6e614eUL

#define NANOVDB_MAGIC_GRID 0x314244566f6e614eUL

#define NANOVDB_MAGIC_MASK 0x00FFFFFFFFFFFFFFUL

#define NANOVDB_MAGIC_NODE 0x334244566f6e614eUL

#define NANOVDB_MAGIC_NUMB 0x304244566f6e614eUL

#define NANOVDB_MAJOR_VERSION_NUMBER 32

#define NANOVDB_MINOR_VERSION_NUMBER 7

#define NANOVDB_NEW_ACCESSOR_METHODS

#define NANOVDB_PATCH_VERSION_NUMBER 0

#define NANOVDB_USE_SINGLE_ROOT_KEY

#define TBB_SUPPRESS_DEPRECATED_MESSAGES 1

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