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/*=========================================================================
Program: Visualization Toolkit
Module: vtkImplicitFunction.h
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
// .NAME vtkImplicitFunction - abstract interface for implicit functions
// .SECTION Description
// vtkImplicitFunction specifies an abstract interface for implicit
// functions. Implicit functions are real valued functions defined in 3D
// space, w = F(x,y,z). Two primitive operations are required: the ability to
// evaluate the function, and the function gradient at a given point. The
// implicit function divides space into three regions: on the surface
// (F(x,y,z)=w), outside of the surface (F(x,y,z)>c), and inside the
// surface (F(x,y,z)<c). (When c is zero, positive values are outside,
// negative values are inside, and zero is on the surface. Note also
// that the function gradient points from inside to outside.)
//
// Implicit functions are very powerful. It is possible to represent almost
// any type of geometry with the level sets w = const, especially if you use
// boolean combinations of implicit functions (see vtkImplicitBoolean).
//
// vtkImplicitFunction provides a mechanism to transform the implicit
// function(s) via a vtkAbstractTransform. This capability can be used to
// translate, orient, scale, or warp implicit functions. For example,
// a sphere implicit function can be transformed into an oriented ellipse.
// .SECTION Caveats
// The transformation transforms a point into the space of the implicit
// function (i.e., the model space). Typically we want to transform the
// implicit model into world coordinates. In this case the inverse of the
// transformation is required.
// .SECTION See Also
// vtkAbstractTransform vtkSphere vtkCylinder vtkImplicitBoolean vtkPlane
// vtkPlanes vtkQuadric vtkImplicitVolume vtkSampleFunction vtkCutter
// vtkClipPolyData
#ifndef __vtkImplicitFunction_h
#define __vtkImplicitFunction_h
#include "vtkObject.h"
class vtkAbstractTransform;
class VTK_COMMON_EXPORT vtkImplicitFunction : public vtkObject
{
public:
vtkTypeMacro(vtkImplicitFunction,vtkObject);
void PrintSelf(ostream& os, vtkIndent indent);
// Description:
// Overload standard modified time function. If Transform is modified,
// then this object is modified as well.
unsigned long GetMTime();
// Description:
// Evaluate function at position x-y-z and return value. Point x[3] is
// transformed through transform (if provided).
double FunctionValue(const double x[3]);
double FunctionValue(double x, double y, double z) {
double xyz[3] = {x, y, z}; return this->FunctionValue(xyz); };
// Description:
// Evaluate function gradient at position x-y-z and pass back vector. Point
// x[3] is transformed through transform (if provided).
void FunctionGradient(const double x[3], double g[3]);
double *FunctionGradient(const double x[3]) {
this->FunctionGradient(x,this->ReturnValue);
return this->ReturnValue; };
double *FunctionGradient(double x, double y, double z) {
double xyz[3] = {x, y, z}; return this->FunctionGradient(xyz); };
// Description:
// Set/Get a transformation to apply to input points before
// executing the implicit function.
virtual void SetTransform(vtkAbstractTransform*);
virtual void SetTransform(const double elements[16]);
vtkGetObjectMacro(Transform,vtkAbstractTransform);
// Description:
// Evaluate function at position x-y-z and return value. You should
// generally not call this method directly, you should use
// FunctionValue() instead. This method must be implemented by
// any derived class.
virtual double EvaluateFunction(double x[3]) = 0;
double EvaluateFunction(double x, double y, double z) {
double xyz[3] = {x, y, z}; return this->EvaluateFunction(xyz); };
// Description:
// Evaluate function gradient at position x-y-z and pass back vector.
// You should generally not call this method directly, you should use
// FunctionGradient() instead. This method must be implemented by
// any derived class.
virtual void EvaluateGradient(double x[3], double g[3]) = 0;
protected:
vtkImplicitFunction();
~vtkImplicitFunction();
vtkAbstractTransform *Transform;
double ReturnValue[3];
private:
vtkImplicitFunction(const vtkImplicitFunction&); // Not implemented.
void operator=(const vtkImplicitFunction&); // Not implemented.
};
#endif
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