vtkHull Class Reference

#include <vtkHull.h>

Inheritance diagram for vtkHull:

[legend]Collaboration diagram for vtkHull:

[legend]List of all members.

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.

Created by:

Avila, Lisa

CVS contributions (if > 5%):

Avila, Lisa (45%)
Schroeder, Will (41%)

CVS logs (CVSweb):

.h (/Graphics/vtkHull.h)
.cxx (/Graphics/vtkHull.cxx)

Tests:: vtkHull (Tests)

Definition at line 64 of file vtkHull.h.

Public Types

typedef vtkPolyDataToPolyDataFilter 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

vtkHull * New ()

int IsTypeOf (const char *type)

vtkHull * SafeDownCast (vtkObject *o)

Protected Member Functions

vtkHull ()

~vtkHull ()

void ComputePlaneDistances ()

void ClipPolygonsFromPlanes (vtkPoints *points, vtkCellArray *polys, double *bounds)

void CreateInitialPolygon (double *, int, double *)

void Execute ()

Protected Attributes

double * Planes

int PlanesStorageSize

int NumberOfPlanes

Member Typedef Documentation

typedef vtkPolyDataToPolyDataFilter vtkHull::Superclass

Reimplemented from vtkPolyDataToPolyDataFilter.
Definition at line 68 of file vtkHull.h.

Constructor & Destructor Documentation

vtkHull::vtkHull ( ) [protected]

vtkHull::~vtkHull ( ) [protected]

Member Function Documentation

vtkHull* vtkHull::New ( ) [static]

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

virtual const char* vtkHull::GetClassName ( ) [virtual]

Reimplemented from vtkPolyDataToPolyDataFilter.

int vtkHull::IsTypeOf ( const char * type ) [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 vtkPolyDataToPolyDataFilter.

virtual int vtkHull::IsA ( const char * type ) [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 vtkPolyDataToPolyDataFilter.

vtkHull* vtkHull::SafeDownCast ( vtkObject * o ) [static]

Reimplemented from vtkPolyDataToPolyDataFilter.

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 vtkPolyDataToPolyDataFilter.

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 ( ) [protected]

void vtkHull::ClipPolygonsFromPlanes ( vtkPoints * points,

vtkCellArray * polys,

double * bounds

) [protected]

void vtkHull::CreateInitialPolygon ( double * ,

int ,

double *

) [protected]

void vtkHull::Execute ( ) [protected, virtual]

This method is the old style execute method
Reimplemented from vtkSource.

Member Data Documentation

double* vtkHull::Planes [protected]

Definition at line 161 of file vtkHull.h.

int vtkHull::PlanesStorageSize [protected]

Definition at line 166 of file vtkHull.h.

int vtkHull::NumberOfPlanes [protected]

Definition at line 169 of file vtkHull.h.

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

dox/Graphics/vtkHull.h


Public Types
typedef vtkPolyDataToPolyDataFilter	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
vtkHull *	New ()
int	IsTypeOf (const char *type)
vtkHull *	SafeDownCast (vtkObject *o)
Protected Member Functions
	vtkHull ()
	~vtkHull ()
void	ComputePlaneDistances ()
void	ClipPolygonsFromPlanes (vtkPoints points, vtkCellArray polys, double *bounds)
void	CreateInitialPolygon (double , int, double )
void	Execute ()
Protected Attributes
double *	Planes
int	PlanesStorageSize
int	NumberOfPlanes