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Program: Visualization Toolkit
Module: vtkImplicitSelectionLoop.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 vtkImplicitSelectionLoop - implicit function for a selection loop
// .SECTION Description
// vtkImplicitSelectionLoop computes the implicit function value and
// function gradient for a irregular, cylinder-like object whose cross
// section is defined by a set of points forming a loop. The loop need
// not be convex nor its points coplanar. However, the loop must be
// non-self-intersecting when projected onto the plane defined by the
// accumulated cross product around the loop (i.e., the axis of the
// loop). (Alternatively, you can specify the normal to use.)
// The following procedure is used to compute the implicit function
// value for a point x. Each point of the loop is first projected onto
// the plane defined by the loop normal. This forms a polygon. Then,
// to evaluate the implicit function value, inside/outside tests are
// used to determine if x is inside the polygon, and the distance to
// the loop boundary is computed (negative values are inside the
// loop).
// One example application of this implicit function class is to draw a
// loop on the surface of a mesh, and use the loop to clip or extract
// cells from within the loop. Remember, the selection loop is "infinite"
// in length, you can use a plane (in boolean combination) to cap the extent
// of the selection loop. Another trick is to use a connectivity filter to
// extract the closest region to a given point (i.e., one of the points used
// to define the selection loop).
// .SECTION See Also
// vtkImplicitFunction vtkImplicitBoolean vtkExtractGeometry vtkClipPolyData
// vtkConnectivityFilter vtkPolyDataConnectivityFilter
#ifndef __vtkImplicitSelectionLoop_h
#define __vtkImplicitSelectionLoop_h
#include "vtkImplicitFunction.h"
class vtkPoints;
class vtkPolygon;
class VTK_FILTERING_EXPORT vtkImplicitSelectionLoop : public vtkImplicitFunction
// Description:
// Standard VTK methods for printing and type information.
void PrintSelf(ostream& os, vtkIndent indent);
// Description:
// Instantiate object with no initial loop.
static vtkImplicitSelectionLoop *New();
// Description:
// Evaluate selection loop returning a signed distance.
double EvaluateFunction(double x[3]);
double EvaluateFunction(double x, double y, double z)
{return this->vtkImplicitFunction::EvaluateFunction(x, y, z); } ;
// Description:
// Evaluate selection loop returning the gradient.
void EvaluateGradient(double x[3], double n[3]);
// Description:
// Set/Get the array of point coordinates defining the loop. There must
// be at least three points used to define a loop.
virtual void SetLoop(vtkPoints*);
// Description:
// Turn on/off automatic normal generation. By default, the normal is
// computed from the accumulated cross product of the edges. You can also
// specify the normal to use.
// Description:
// Set / get the normal used to determine whether a point is inside or outside
// the selection loop.
// Description:
// Overload GetMTime() because we depend on the Loop
unsigned long GetMTime();
vtkPoints *Loop;
double Normal[3];
int AutomaticNormalGeneration;
void Initialize();
vtkPolygon *Polygon;
double Origin[3];
double Bounds[6]; //bounds of the projected polyon
double DeltaX;
double DeltaY;
double DeltaZ;
vtkTimeStamp InitializationTime;
vtkImplicitSelectionLoop(const vtkImplicitSelectionLoop&); // Not implemented.
void operator=(const vtkImplicitSelectionLoop&); // Not implemented.