vtkViewDependentErrorMetric Class Reference

#include <vtkViewDependentErrorMetric.h>

Inheritance diagram for vtkViewDependentErrorMetric:

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Collaboration diagram for vtkViewDependentErrorMetric:

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List of all members.

Detailed Description

Objects that compute a screen-based error during cell tessellation.

It is a concrete error metric, based on a geometric criterium in the screen space: the variation of the projected edge from a projected straight line

See also:: vtkGenericCellTessellator vtkGenericSubdivisionErrorMetric

Tests:: vtkViewDependentErrorMetric (Tests)

Definition at line 39 of file vtkViewDependentErrorMetric.h.


typedef vtkGenericSubdivisionErrorMetric	Superclass
static int	IsTypeOf (const char *type)
static vtkViewDependentErrorMetric *	SafeDownCast (vtkObject *o)
virtual const char *	GetClassName ()
virtual int	IsA (const char *type)
void	PrintSelf (ostream &os, vtkIndent indent)
Public Member Functions
void	SetPixelTolerance (double value)

virtual double	GetPixelTolerance ()

virtual vtkViewport *	GetViewport ()
void	SetViewport (vtkViewport *viewport)

int	RequiresEdgeSubdivision (double leftPoint, double midPoint, double *rightPoint, double alpha)

double	GetError (double leftPoint, double midPoint, double *rightPoint, double alpha)
Static Public Member Functions
static vtkViewDependentErrorMetric *	New ()
Protected Member Functions
	vtkViewDependentErrorMetric ()
	~vtkViewDependentErrorMetric ()

double	Distance2LinePoint (double x[2], double y[2], double z[2])
Protected Attributes
double	PixelTolerance
vtkViewport *	Viewport
vtkCoordinate *	Coordinate

Member Typedef Documentation

typedef vtkGenericSubdivisionErrorMetric vtkViewDependentErrorMetric::Superclass

Standard VTK type and error macros.

Reimplemented from vtkGenericSubdivisionErrorMetric.

Definition at line 48 of file vtkViewDependentErrorMetric.h.

Constructor & Destructor Documentation

vtkViewDependentErrorMetric::vtkViewDependentErrorMetric ( ) [protected]

vtkViewDependentErrorMetric::~vtkViewDependentErrorMetric ( ) [protected]

Member Function Documentation

static vtkViewDependentErrorMetric* vtkViewDependentErrorMetric::New ( ) [static]

Construct the error metric with a default squared screen-based geometric accuracy measured in pixels equal to 0.25 (0.5^2).

Reimplemented from vtkObject.

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

Standard VTK type and error macros.

Reimplemented from vtkGenericSubdivisionErrorMetric.

static int vtkViewDependentErrorMetric::IsTypeOf ( const char * type ) [static]

Standard VTK type and error macros.

Reimplemented from vtkGenericSubdivisionErrorMetric.

virtual int vtkViewDependentErrorMetric::IsA ( const char * type ) [virtual]

Standard VTK type and error macros.

Reimplemented from vtkGenericSubdivisionErrorMetric.

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

Standard VTK type and error macros.

Reimplemented from vtkGenericSubdivisionErrorMetric.

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

Standard VTK type and error macros.

Reimplemented from vtkGenericSubdivisionErrorMetric.

virtual double vtkViewDependentErrorMetric::GetPixelTolerance ( ) [virtual]

Return the squared screen-based geometric accurary measured in pixels. An accuracy less or equal to 0.25 (0.5^2) ensures that the screen-space interpolation of a mid-point matchs exactly with the projection of the mid-point (a value less than 1 but greater than 0.25 is not enough, because of 8-neighbors). Maybe it is useful for lower accuracy in case of anti-aliasing?

Postcondition:: positive_result: result>0

void vtkViewDependentErrorMetric::SetPixelTolerance ( double value )

Set the squared screen-based geometric accuracy measured in pixels. Subdivision will be required if the square distance between the projection of the real point and the straight line passing through the projection of the vertices of the edge is greater than `value'. For instance, 0.25 will give better result than 1.

Precondition:: positive_value: value>0

virtual vtkViewport* vtkViewDependentErrorMetric::GetViewport ( ) [virtual]

Set/Get the renderer with `renderer' on which the error metric is based. The error metric use the active camera of the renderer.

void vtkViewDependentErrorMetric::SetViewport ( vtkViewport * viewport )

Set/Get the renderer with `renderer' on which the error metric is based. The error metric use the active camera of the renderer.

int vtkViewDependentErrorMetric::RequiresEdgeSubdivision	(	double *	leftPoint,
		double *	midPoint,
		double *	rightPoint,
		double	alpha
	)			`[virtual]`

Does the edge need to be subdivided according to the distance between the line passing through its endpoints in screen space and the projection of its mid point? The edge is defined by its `leftPoint' and its `rightPoint'. `leftPoint', `midPoint' and `rightPoint' have to be initialized before calling RequiresEdgeSubdivision(). Their format is global coordinates, parametric coordinates and point centered attributes: xyx rst abc de... `alpha' is the normalized abscissa of the midpoint along the edge. (close to 0 means close to the left point, close to 1 means close to the right point)

Precondition:

leftPoint_exists: leftPoint!=0

midPoint_exists: midPoint!=0

rightPoint_exists: rightPoint!=0

clamped_alpha: alpha>0 && alpha<1

valid_size: sizeof(leftPoint)=sizeof(midPoint)=sizeof(rightPoint) =GetAttributeCollection()->GetNumberOfPointCenteredComponents()+6

Implements vtkGenericSubdivisionErrorMetric.

double vtkViewDependentErrorMetric::GetError	(	double *	leftPoint,
		double *	midPoint,
		double *	rightPoint,
		double	alpha
	)			`[virtual]`

Return the error at the mid-point. The type of error depends on the state of the concrete error metric. For instance, it can return an absolute or relative error metric. See RequiresEdgeSubdivision() for a description of the arguments.

Precondition:

leftPoint_exists: leftPoint!=0

midPoint_exists: midPoint!=0

rightPoint_exists: rightPoint!=0

clamped_alpha: alpha>0 && alpha<1

valid_size: sizeof(leftPoint)=sizeof(midPoint)=sizeof(rightPoint) =GetAttributeCollection()->GetNumberOfPointCenteredComponents()+6

Postcondition:: positive_result: result>=0

Implements vtkGenericSubdivisionErrorMetric.

double vtkViewDependentErrorMetric::Distance2LinePoint	(	double	x[2],
		double	y[2],
		double	z[2]
	)			`[protected]`

Square distance between a straight line (defined by points x and y) and a point z. Property: if x and y are equal, the line is a point and the result is the square distance between points x and z.