Basic type: arbitrarily oriented 3D bounding box. More...

#include <bbox3d.h>

Public Member Functions
	GfBBox3d ()
	The default constructor leaves the box empty, the transformation matrix identity, and the zero-areaprimitives flag" `false`.

	GfBBox3d (const GfRange3d &box)
	This constructor takes a box and sets the matrix to identity.

	GfBBox3d (const GfRange3d &box, const GfMatrix4d &matrix)
	This constructor takes a box and a transformation matrix.

void	Set (const GfRange3d &box, const GfMatrix4d &matrix)
	Sets the axis-aligned box and transformation matrix.

void	SetMatrix (const GfMatrix4d &matrix)
	Sets the transformation matrix only.

void	SetRange (const GfRange3d &box)
	Sets the range of the axis-aligned box only.

const GfRange3d &	GetRange () const
	Returns the range of the axis-aligned untransformed box.

const GfRange3d &	GetBox () const
	Returns the range of the axis-aligned untransformed box.

const GfMatrix4d &	GetMatrix () const
	Returns the transformation matrix.

const GfMatrix4d &	GetInverseMatrix () const
	Returns the inverse of the transformation matrix.

void	SetHasZeroAreaPrimitives (bool hasThem)
	Sets the zero-area primitives flag to the given value.

bool	HasZeroAreaPrimitives () const
	Returns the current state of the zero-areaprimitives flag".

GF_API double	GetVolume () const
	Returns the volume of the box (0 for an empty box).

void	Transform (const GfMatrix4d &matrix)
	Transforms the bounding box by the given matrix, which is assumed to be a global transformation to apply to the box.

GF_API GfRange3d	ComputeAlignedRange () const
	Returns the axis-aligned range (as a `GfRange3d`) that results from applying the transformation matrix to the wxis-aligned box and aligning the result.

GfRange3d	ComputeAlignedBox () const
	Returns the axis-aligned range (as a `GfRange3d`) that results from applying the transformation matrix to the axis-aligned box and aligning the result.

GF_API GfVec3d	ComputeCentroid () const
	Returns the centroid of the bounding box.

bool	operator== (const GfBBox3d &b) const
	Component-wise equality test.

bool	operator!= (const GfBBox3d &that) const
	Component-wise inequality test.

Static Public Member Functions
static GF_API GfBBox3d	Combine (const GfBBox3d &b1, const GfBBox3d &b2)
	Combines two bboxes, returning a new bbox that contains both.

Friends
size_t	hash_value (const GfBBox3d &b)
	Hash.

Detailed Description

Basic type: arbitrarily oriented 3D bounding box.

This class represents a three-dimensional bounding box as an axis-aligned box (GfRange3d) and a matrix (GfMatrix4d) to transform it into the correct space.

A GfBBox3d is more useful than using just GfRange3d instances (which are always axis-aligned) for these reasons:

When an axis-aligned bounding box is transformed several times, each transformation can result in inordinate growth of the bounding box. By storing the transformation separately, it can be applied once at the end, resulting in a much better fit. For example, if the bounding box at the leaf of a scene graph is transformed through several levels of the graph hierarchy to the coordinate space at the root, a GfBBox3d is generally much smaller than the GfRange3d computed by transforming the box at each level.

When two or more such bounding boxes are combined, having the transformations stored separately means that there is a better opportunity to choose a better coordinate space in which to combine the boxes.

The Zero-area Primitives Flag

When bounding boxes are used in intersection test culling, it is sometimes useful to extend them a little bit to allow lower-dimensional objects with zero area, such as lines and points, to be intersected. For example, consider a cube constructed of line segments. The bounding box for this shape fits the cube exactly. If an application wants to allow a near-miss of the silhouette edges of the cube to be considered an intersection, it has to loosen the bbox culling test a little bit.

To distinguish when this loosening is necessary, each GfBBox3d instance maintains a flag indicating whether any zero-area primitives are contained within it. The application is responsible for setting this flag correctly by calling SetHasZeroAreaPrimitives(). The flag can be accessed during intersection tests by calling HasZeroAreaPrimitives(). This flag is set by default in all constructors to false.

Definition at line 67 of file bbox3d.h.

Constructor & Destructor Documentation

◆ GfBBox3d() [1/3]

GfBBox3d ( )

inline

The default constructor leaves the box empty, the transformation matrix identity, and the zero-areaprimitives flag" false.

Definition at line 74 of file bbox3d.h.

◆ GfBBox3d() [2/3]

GfBBox3d ( const GfRange3d & box )

inline

This constructor takes a box and sets the matrix to identity.

Definition at line 82 of file bbox3d.h.

◆ GfBBox3d() [3/3]

GfBBox3d	(	const GfRange3d &	box,
		const GfMatrix4d &	matrix
	)

inline

This constructor takes a box and a transformation matrix.

Definition at line 91 of file bbox3d.h.

Member Function Documentation

◆ Combine()

static GF_API GfBBox3d Combine	(	const GfBBox3d &	b1,
		const GfBBox3d &	b2
	)

static

Combines two bboxes, returning a new bbox that contains both.

This uses the coordinate space of one of the two original boxes as the space of the result; it uses the one that produces whe smaller of the two resulting boxes.

◆ ComputeAlignedBox()

GfRange3d ComputeAlignedBox ( ) const

inline

Returns the axis-aligned range (as a GfRange3d) that results from applying the transformation matrix to the axis-aligned box and aligning the result.

This synonym for ComputeAlignedRange exists for compatibility purposes.

Definition at line 169 of file bbox3d.h.

◆ ComputeAlignedRange()

GF_API GfRange3d ComputeAlignedRange ( ) const

Returns the axis-aligned range (as a GfRange3d) that results from applying the transformation matrix to the wxis-aligned box and aligning the result.

◆ ComputeCentroid()

GF_API GfVec3d ComputeCentroid ( ) const

Returns the centroid of the bounding box.

The centroid is computed as the transformed centroid of the range.

◆ GetBox()

const GfRange3d & GetBox ( ) const

inline

Returns the range of the axis-aligned untransformed box.

This synonym of GetRange exists for compatibility purposes.

Definition at line 121 of file bbox3d.h.

◆ GetInverseMatrix()

const GfMatrix4d & GetInverseMatrix ( ) const

inline

Returns the inverse of the transformation matrix.

This will be the identity matrix if the transformation matrix is not invertible.

Definition at line 132 of file bbox3d.h.

◆ GetMatrix()

const GfMatrix4d & GetMatrix ( ) const

inline

Returns the transformation matrix.

Definition at line 126 of file bbox3d.h.

◆ GetRange()

const GfRange3d & GetRange ( ) const

inline

Returns the range of the axis-aligned untransformed box.

Definition at line 115 of file bbox3d.h.

◆ GetVolume()

GF_API double GetVolume ( ) const

Returns the volume of the box (0 for an empty box).

◆ HasZeroAreaPrimitives()

bool HasZeroAreaPrimitives ( ) const

inline

Returns the current state of the zero-areaprimitives flag".

Definition at line 144 of file bbox3d.h.

◆ operator!=()

bool operator!= ( const GfBBox3d & that ) const

inline

Component-wise inequality test.

The axis-aligned boxes and transformation matrices match exactly for bboxes to be considered equal. (To compare equality of the actual boxes, you can compute both aligned boxes and test the results for equality.)

Definition at line 206 of file bbox3d.h.

◆ operator==()

bool operator== ( const GfBBox3d & b ) const

inline

Component-wise equality test.

The axis-aligned boxes and transformation matrices match exactly for bboxes to be considered equal. (To compare equality of the actual boxes, you can compute both aligned boxes and test the results for equality.)

Definition at line 197 of file bbox3d.h.

◆ Set()

void Set	(	const GfRange3d &	box,
		const GfMatrix4d &	matrix
	)

inline

Sets the axis-aligned box and transformation matrix.

Definition at line 97 of file bbox3d.h.

◆ SetHasZeroAreaPrimitives()

void SetHasZeroAreaPrimitives ( bool hasThem )

inline

Sets the zero-area primitives flag to the given value.

Definition at line 138 of file bbox3d.h.

◆ SetMatrix()

void SetMatrix ( const GfMatrix4d & matrix )

inline

Sets the transformation matrix only.

The axis-aligned box is not modified.

Definition at line 104 of file bbox3d.h.

◆ SetRange()

void SetRange ( const GfRange3d & box )

inline

Sets the range of the axis-aligned box only.

The transformation matrix is not modified.

Definition at line 110 of file bbox3d.h.

◆ Transform()

void Transform ( const GfMatrix4d & matrix )

inline

Transforms the bounding box by the given matrix, which is assumed to be a global transformation to apply to the box.

Therefore, this just post-multiplies the box's matrix by matrix.

Definition at line 155 of file bbox3d.h.

Friends And Related Function Documentation

◆ hash_value

size_t hash_value ( const GfBBox3d & b )

friend

Hash.

Definition at line 186 of file bbox3d.h.

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

pxr/base/gf/bbox3d.h

Public Member Functions

Static Public Member Functions

Friends

Detailed Description

Constructor & Destructor Documentation

◆ GfBBox3d() [1/3]

◆ GfBBox3d() [2/3]

◆ GfBBox3d() [3/3]

Member Function Documentation

◆ Combine()

◆ ComputeAlignedBox()

◆ ComputeAlignedRange()

◆ ComputeCentroid()

◆ GetBox()

◆ GetInverseMatrix()

◆ GetMatrix()

◆ GetRange()

◆ GetVolume()

◆ HasZeroAreaPrimitives()

◆ operator!=()

◆ operator==()

◆ Set()

◆ SetHasZeroAreaPrimitives()

◆ SetMatrix()

◆ SetRange()

◆ Transform()

Friends And Related Function Documentation

◆ hash_value