vtkHull Class Reference

#include <vtkHull.h>

Inheritance diagram for vtkHull:

[legend]

Collaboration diagram for vtkHull:

[legend]

List of all members.

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Detailed Description

produce an n-sided convex hull

vtkHull is a filter which will produce an n-sided convex hull given a set of n planes. (The convex hull bounds the input polygonal data.) The hull is generated by squeezing the planes towards the input vtkPolyData, until the planes just touch the vtkPolyData. Then, the resulting planes are used to generate a polyhedron (i.e., hull) that is represented by triangles.

The n planes can be defined in a number of ways including 1) manually specifying each plane; 2) choosing the six face planes of the input's bounding box; 3) choosing the eight vertex planes of the input's bounding box; 4) choosing the twelve edge planes of the input's bounding box; and/or 5) using a recursively subdivided octahedron. Note that when specifying planes, the plane normals should point outside of the convex region.

The output of this filter can be used in combination with vtkLODActor to represent a levels-of-detail in the LOD hierarchy. Another use of this class is to manually specify the planes, and then generate the polyhedron from the planes (without squeezing the planes towards the input). The method GenerateHull() is used to do this.

Tests:

vtkHull (Tests)

Definition at line 53 of file vtkHull.h.

Public Types
typedef vtkPolyDataAlgorithm	Superclass
Public Member Functions
virtual const char *	GetClassName ()
virtual int	IsA (const char *type)
void	PrintSelf (ostream &os, vtkIndent indent)
void	RemoveAllPlanes (void)
void	SetPlanes (vtkPlanes *planes)
void	AddCubeVertexPlanes ()
void	AddCubeEdgePlanes ()
void	AddCubeFacePlanes ()
void	AddRecursiveSpherePlanes (int level)
int	AddPlane (double A, double B, double C)
int	AddPlane (double plane[3])
void	SetPlane (int i, double A, double B, double C)
void	SetPlane (int i, double plane[3])
int	AddPlane (double A, double B, double C, double D)
int	AddPlane (double plane[3], double D)
void	SetPlane (int i, double A, double B, double C, double D)
void	SetPlane (int i, double plane[3], double D)
virtual int	GetNumberOfPlanes ()
void	GenerateHull (vtkPolyData *pd, double *bounds)
void	GenerateHull (vtkPolyData *pd, double xmin, double xmax, double ymin, double ymax, double zmin, double zmax)
Static Public Member Functions
static vtkHull *	New ()
static int	IsTypeOf (const char *type)
static vtkHull *	SafeDownCast (vtkObject *o)
Protected Member Functions
	vtkHull ()
	~vtkHull ()
void	ComputePlaneDistances (vtkPolyData *input)
void	ClipPolygonsFromPlanes (vtkPoints *points, vtkCellArray *polys, double *bounds)
void	CreateInitialPolygon (double *, int, double *)
int	RequestData (vtkInformation *, vtkInformationVector **, vtkInformationVector *)
Protected Attributes
double *	Planes
int	PlanesStorageSize
int	NumberOfPlanes

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Member Typedef Documentation

typedef vtkPolyDataAlgorithm vtkHull::Superclass

Reimplemented from vtkPolyDataAlgorithm.

Definition at line 57 of file vtkHull.h.

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Constructor & Destructor Documentation

vtkHull::vtkHull

(

)

[protected]

vtkHull::~vtkHull

(

)

[protected]

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Member Function Documentation

static vtkHull* vtkHull::New

(

)

[static]

Create an object with Debug turned off, modified time initialized to zero, and reference counting on.

Reimplemented from vtkPolyDataAlgorithm.

virtual const char* vtkHull::GetClassName

(

)

[virtual]

Reimplemented from vtkPolyDataAlgorithm.

static int vtkHull::IsTypeOf

(

const char *

name

)

[static]

Return 1 if this class type is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeRevisionMacro found in vtkSetGet.h.

Reimplemented from vtkPolyDataAlgorithm.

virtual int vtkHull::IsA

(

const char *

name

)

[virtual]

Return 1 if this class is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeRevisionMacro found in vtkSetGet.h.

Reimplemented from vtkPolyDataAlgorithm.

static vtkHull* vtkHull::SafeDownCast

(

vtkObject *

o

)

[static]

Reimplemented from vtkPolyDataAlgorithm.

void vtkHull::PrintSelf	(	ostream &	os,
		vtkIndent	indent
	)			[virtual]

Methods invoked by print to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from vtkPolyDataAlgorithm.

void vtkHull::RemoveAllPlanes

(

void

)

Remove all planes from the current set of planes.

int vtkHull::AddPlane	(	double	A,
		double	B,
		double	C
	)

Add a plane to the current set of planes. It will be added at the end of the list, and an index that can later be used to set this plane's normal will be returned. The values A, B, C are from the plane equation Ax + By + Cz + D = 0. This vector does not have to have unit length (but it must have a non-zero length!). If a value 0 > i >= -NumberOfPlanes is returned, then the plane is parallel with a previously inserted plane, and |-i-1| is the index of the plane that was previously inserted. If a value i < -NumberOfPlanes is returned, then the plane normal is zero length.

int vtkHull::AddPlane

(

double

plane[3]

)

Add a plane to the current set of planes. It will be added at the end of the list, and an index that can later be used to set this plane's normal will be returned. The values A, B, C are from the plane equation Ax + By + Cz + D = 0. This vector does not have to have unit length (but it must have a non-zero length!). If a value 0 > i >= -NumberOfPlanes is returned, then the plane is parallel with a previously inserted plane, and |-i-1| is the index of the plane that was previously inserted. If a value i < -NumberOfPlanes is returned, then the plane normal is zero length.

void vtkHull::SetPlane	(	int	i,
		double	A,
		double	B,
		double	C
	)

Set the normal values for plane i. This is a plane that was already added to the current set of planes with AddPlane(), and is now being modified. The values A, B, C are from the plane equation Ax + By + Cz + D = 0. This vector does not have to have unit length. Note that D is set to zero, except in the case of the method taking a vtkPlanes* argument, where it is set to the D value defined there.

void vtkHull::SetPlane	(	int	i,
		double	plane[3]
	)

Set the normal values for plane i. This is a plane that was already added to the current set of planes with AddPlane(), and is now being modified. The values A, B, C are from the plane equation Ax + By + Cz + D = 0. This vector does not have to have unit length. Note that D is set to zero, except in the case of the method taking a vtkPlanes* argument, where it is set to the D value defined there.

int vtkHull::AddPlane	(	double	A,
		double	B,
		double	C,
		double	D
	)

Variations of AddPlane()/SetPlane() that allow D to be set. These methods are used when GenerateHull() is used.

int vtkHull::AddPlane	(	double	plane[3],
		double	D
	)

Variations of AddPlane()/SetPlane() that allow D to be set. These methods are used when GenerateHull() is used.

void vtkHull::SetPlane	(	int	i,
		double	A,
		double	B,
		double	C,
		double	D
	)

Variations of AddPlane()/SetPlane() that allow D to be set. These methods are used when GenerateHull() is used.

void vtkHull::SetPlane	(	int	i,
		double	plane[3],
		double	D
	)

Variations of AddPlane()/SetPlane() that allow D to be set. These methods are used when GenerateHull() is used.

void vtkHull::SetPlanes

(

vtkPlanes *

planes

)

Set all the planes at once using a vtkPlanes implicit function. This also sets the D value, so it can be used with GenerateHull().

virtual int vtkHull::GetNumberOfPlanes

(

)

[virtual]

Get the number of planes in the current set of planes.

void vtkHull::AddCubeVertexPlanes

(

)

Add the 8 planes that represent the vertices of a cube - the combination of the three face planes connecting to a vertex - (1,1,1), (1,1,-1), (1,-1,1), (1,-1,1), (-1,1,1), (-1,1,-1), (-1,-1,1), (-1,-1-1).

void vtkHull::AddCubeEdgePlanes

(

)

Add the 12 planes that represent the edges of a cube - halfway between the two connecting face planes - (1,1,0), (-1,-1,0), (-1,1,0), (1,-1,0), (0,1,1), (0,-1,-1), (0,1,-1), (0,-1,1), (1,0,1), (-1,0,-1), (1,0,-1), (-1,0,1)

void vtkHull::AddCubeFacePlanes

(

)

Add the six planes that make up the faces of a cube - (1,0,0), (-1, 0, 0), (0,1,0), (0,-1,0), (0,0,1), (0,0,-1)

void vtkHull::AddRecursiveSpherePlanes

(

int

level

)

Add the planes that represent the normals of the vertices of a polygonal sphere formed by recursively subdividing the triangles in an octahedron. Each triangle is subdivided by connecting the midpoints of the edges thus forming 4 smaller triangles. The level indicates how many subdivisions to do with a level of 0 used to add the 6 planes from the original octahedron, level 1 will add 18 planes, and so on.

void vtkHull::GenerateHull	(	vtkPolyData *	pd,
		double *	bounds
	)

A special method that is used to generate a polyhedron directly from a set of n planes. The planes that are supplied by the user are not squeezed towards the input data (in fact the user need not specify an input). To use this method, you must provide an instance of vtkPolyData into which the points and cells defining the polyhedron are placed. You must also provide a bounding box where you expect the resulting polyhedron to lie. This can be a very generous fit, it's only used to create the initial polygons that are eventually clipped.

void vtkHull::GenerateHull	(	vtkPolyData *	pd,
		double	xmin,
		double	xmax,
		double	ymin,
		double	ymax,
		double	zmin,
		double	zmax
	)

A special method that is used to generate a polyhedron directly from a set of n planes. The planes that are supplied by the user are not squeezed towards the input data (in fact the user need not specify an input). To use this method, you must provide an instance of vtkPolyData into which the points and cells defining the polyhedron are placed. You must also provide a bounding box where you expect the resulting polyhedron to lie. This can be a very generous fit, it's only used to create the initial polygons that are eventually clipped.

void vtkHull::ComputePlaneDistances

(

vtkPolyData *

input

)

[protected]

void vtkHull::ClipPolygonsFromPlanes	(	vtkPoints *	points,
		vtkCellArray *	polys,
		double *	bounds
	)			[protected]

void vtkHull::CreateInitialPolygon	(	double *	,
		int	,
		double *
	)			[protected]

int vtkHull::RequestData	(	vtkInformation *	request,
		vtkInformationVector **	inputVector,
		vtkInformationVector *	outputVector
	)			[protected, virtual]

This is called by the superclass. This is the method you should override.

Reimplemented from vtkPolyDataAlgorithm.

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Member Data Documentation

double* vtkHull::Planes [protected]

Definition at line 150 of file vtkHull.h.

int vtkHull::PlanesStorageSize [protected]

Definition at line 155 of file vtkHull.h.

int vtkHull::NumberOfPlanes [protected]

Definition at line 158 of file vtkHull.h.

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

• dox/Graphics/vtkHull.h