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Program: Visualization Toolkit
Module: vtkPiecewiseFunction.h
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or for details.
This software is distributed WITHOUT ANY WARRANTY; without even
PURPOSE. See the above copyright notice for more information.
// .NAME vtkPiecewiseFunction - Defines a 1D piecewise function.
// .SECTION Description
// Defines a piecewise function mapping. This mapping allows the addition
// of control points, and allows the user to control the function between
// the control points. A piecewise hermite curve is used between control
// points, based on the sharpness and midpoint parameters. A sharpness of
// 0 yields a piecewise linear function and a sharpness of 1 yields a
// piecewise constant function. The midpoint is the normalized distance
// between control points at which the curve reaches the median Y value.
// The midpoint and sharpness values specified when adding a node are used
// to control the transition to the next node (the last node's values are
// ignored) Outside the range of nodes, the values are 0 if Clamping is off,
// or the nearest node point if Clamping is on. Using the legacy methods for
// adding points (which do not have Sharpness and Midpoint parameters)
// will default to Midpoint = 0.5 (halfway between the control points) and
// Sharpness = 0.0 (linear).
#ifndef __vtkPiecewiseFunction_h
#define __vtkPiecewiseFunction_h
#include "vtkDataObject.h"
class vtkPiecewiseFunctionInternals;
class VTK_FILTERING_EXPORT vtkPiecewiseFunction : public vtkDataObject
static vtkPiecewiseFunction *New();
void PrintSelf(ostream& os, vtkIndent indent);
void DeepCopy( vtkDataObject *f );
void ShallowCopy( vtkDataObject *f );
// Description:
// Return what type of dataset this is.
int GetDataObjectType() {return VTK_PIECEWISE_FUNCTION;};
// Description:
// Get the number of points used to specify the function
int GetSize();
// Description:
// Add/Remove points to/from the function. If a duplicate point is added
// then the function value is changed at that location.
// Return the index of the point (0 based), or -1 on error.
int AddPoint( double x, double y );
int AddPoint( double x, double y, double midpoint, double sharpness );
int RemovePoint( double x );
// Description:
// Removes all points from the function.
void RemoveAllPoints();
// Description:
// Add a line segment to the function. All points defined between the
// two points specified are removed from the function. This is a legacy
// method that does not allow the specification of the sharpness and
// midpoint values for the two nodes.
void AddSegment( double x1, double y1, double x2, double y2 );
// Description:
// Returns the value of the function at the specified location using
// the specified interpolation.
double GetValue( double x );
// Description:
// For the node specified by index, set/get the
// location (X), value (Y), midpoint, and sharpness
// values at the node.
int GetNodeValue( int index, double val[4] );
int SetNodeValue( int index, double val[4] );
// Description:
// Returns a pointer to the data stored in the table.
// Fills from a pointer to data stored in a similar table. These are
// legacy methods which will be maintained for compatibility - however,
// note that the vtkPiecewiseFunction no longer stores the nodes
// in a double array internally.
double *GetDataPointer();
void FillFromDataPointer(int, double*);
// Description:
// Returns the min and max node locations of the function.
vtkGetVector2Macro( Range, double );
// Description:
// Remove all points out of the new range, and make sure there is a point
// at each end of that range.
// Return 1 on success, 0 otherwise.
int AdjustRange(double range[2]);
// Description:
// Fills in an array of function values evaluated at regular intervals.
// Parameter "stride" is used to step through the output "table".
void GetTable( double x1, double x2, int size, float *table, int stride=1 );
void GetTable( double x1, double x2, int size, double *table, int stride=1 );
// Description:
// Constructs a piecewise function from a table. Function range is
// is set to [x1, x2], function size is set to size, and function points
// are regularly spaced between x1 and x2. Parameter "stride" is
// is step through the input table.
void BuildFunctionFromTable( double x1, double x2, int size,
double *table, int stride=1 );
// Description:
// When zero range clamping is Off, GetValue() returns 0.0 when a
// value is requested outside of the points specified.
// When zero range clamping is On, GetValue() returns the value at
// the value at the lowest point for a request below all points
// specified and returns the value at the highest point for a request
// above all points specified. On is the default.
vtkSetMacro( Clamping, int );
vtkGetMacro( Clamping, int );
vtkBooleanMacro( Clamping, int );
// Description:
// Return the type of function:
// Function Types:
// 0 : Constant (No change in slope between end points)
// 1 : NonDecreasing (Always increasing or zero slope)
// 2 : NonIncreasing (Always decreasing or zero slope)
// 3 : Varied (Contains both decreasing and increasing slopes)
const char *GetType();
// Description:
// Returns the first point location which precedes a non-zero segment of the
// function. Note that the value at this point may be zero.
double GetFirstNonZeroValue();
// Description:
// Clears out the current function. A newly created vtkPiecewiseFunction
// is alreay initialized, so there is no need to call this method which
// in turn simply calls RemoveAllPoints()
void Initialize();
// Description:
// Retrieve an instance of this class from an information object.
static vtkPiecewiseFunction* GetData(vtkInformation* info);
static vtkPiecewiseFunction* GetData(vtkInformationVector* v, int i=0);
// Description:
// Toggle whether to allow duplicate scalar values in the piecewise
// function (off by default).
vtkSetMacro(AllowDuplicateScalars, int);
vtkGetMacro(AllowDuplicateScalars, int);
vtkBooleanMacro(AllowDuplicateScalars, int);
// The internal STL structures
vtkPiecewiseFunctionInternals *Internal;
// Determines the function value outside of defined points
// Zero = always return 0.0 outside of defined points
// One = clamp to the lowest value below defined points and
// highest value above defined points
int Clamping;
// Array of points ((X,Y) pairs)
double *Function;
// Min and max range of function point locations
double Range[2];
// Internal method to sort the vector and update the
// Range whenever a node is added or removed
void SortAndUpdateRange();
int AllowDuplicateScalars;
vtkPiecewiseFunction(const vtkPiecewiseFunction&); // Not implemented.
void operator=(const vtkPiecewiseFunction&); // Not implemented.