/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkPlanes.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$


Copyright (c) 1993-2000 Ken Martin, Will Schroeder, Bill Lorensen 
All rights reserved.

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 * Neither name of Ken Martin, Will Schroeder, or Bill Lorensen nor the names
   of any contributors may be used to endorse or promote products derived
   from this software without specific prior written permission.

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=========================================================================*/
// .NAME vtkPlanes - implicit function for convex set of planes
// .SECTION Description
// vtkPlanes computes the implicit function and function gradient for a set
// of planes. The planes must define a convex space.
//
// The function value is the closest first order distance of a point to the
// convex region defined by the planes. The function gradient is the plane
// normal at the function value.  Note that the normals must point outside of
// the convex region. Thus, a negative function value means that a point is
// inside the convex region.
//
// To define the planes you must create two objects: a subclass of 
// vtkPoints (e.g., vtkPoints) and a subclass of vtkNormals (e.g., 
// vtkNormals). The points define a point on the plane, and the normals
// specify plane normals.

#ifndef __vtkPlanes_h
#define __vtkPlanes_h

#include "vtkImplicitFunction.h"

class vtkPlane;
class vtkCamera;

class VTK_EXPORT vtkPlanes : public vtkImplicitFunction
{
public:
  static vtkPlanes *New();
  vtkTypeMacro(vtkPlanes,vtkImplicitFunction);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description
  // Evaluate plane equations. Return smallest absolute value.
  float EvaluateFunction(float x[3]);
  float EvaluateFunction(float x, float y, float z)
    {return this->vtkImplicitFunction::EvaluateFunction(x, y, z); } ;

  // Description
  // Evaluate planes gradient.
  void EvaluateGradient(float x[3], float n[3]);

  // Description:
  // Specify a list of points defining points through which the planes pass.
  vtkSetObjectMacro(Points,vtkPoints);
  vtkGetObjectMacro(Points,vtkPoints);
  
  // Description:
  // Specify a list of normal vectors for the planes. There is a one-to-one
  // correspondence between plane points and plane normals.
  vtkSetObjectMacro(Normals,vtkNormals);
  vtkGetObjectMacro(Normals,vtkNormals);

  // Description:
  // Specify the planes via a camera frustrum definition.
  void SetFrustumPlanes(float aspect, vtkCamera *camera);

protected:
  vtkPlanes();
  ~vtkPlanes();
  vtkPlanes(const vtkPlanes&) {};
  void operator=(const vtkPlanes&) {};

  vtkPoints *Points;
  vtkNormals *Normals;
  vtkPlane *Plane;

private:
  float Planes[24];

};

#endif


