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

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


Copyright (c) 1993-2000 Ken Martin, Will Schroeder, Bill Lorensen 
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=========================================================================*/
// .NAME vtkTextureMapToSphere - generate texture coordinates by mapping points to sphere
// .SECTION Description
// vtkTextureMapToSphere is a filter that generates 2D texture coordinates by
// mapping input dataset points onto a sphere. The sphere can either be user
// specified or generated automatically. (The sphere is generated
// automatically by computing the center (i.e., averaged coordinates) of the
// sphere.)  Note that the generated texture coordinates range beween
// (0,1). The s-coordinate lies in the angular direction around the z-axis,
// measured counter-clockwise from the x-axis. The t-coordinate lies in the
// angular direction measured down from the north pole towards the south
// pole.
//
// A special ivar controls how the s-coordinate is generated. If PreventSeam
// is set to true, the s-texture varies from 0->1 and then 1->0 (corresponding
// to angles of 0->180 and 180->360).

// .SECTION Caveats
// The resulting texture coordinates will lie between (0,1), and the texture
// coordinates are determined with respect to the modeller's x-y-z coordinate
// system. Use the class vtkTransformTextureCoords to linearly scale and
// shift the origin of the texture coordinates (if necessary).

// .SECTION See Also
// vtkTextureMapToPlane vtkTextureMapToCylinder vtkTextureMapToBox
// vtkTransformTexture vtkThresholdTextureCoords

#ifndef __vtkTextureMapToSphere_h
#define __vtkTextureMapToSphere_h

#include "vtkDataSetToDataSetFilter.h"

class VTK_EXPORT vtkTextureMapToSphere : public vtkDataSetToDataSetFilter 
{
public:
  vtkTypeMacro(vtkTextureMapToSphere,vtkDataSetToDataSetFilter);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Create object with Center (0,0,0) and the PreventSeam ivar is set to
  // true. The sphere center is automatically computed.
  static vtkTextureMapToSphere *New();

  // Description:
  // Specify a point defining the center of the sphere.
  vtkSetVector3Macro(Center,float);
  vtkGetVectorMacro(Center,float,3);

  // Description:
  // Turn on/off automatic sphere generation. This means it automatically
  // finds the sphere center.
  vtkSetMacro(AutomaticSphereGeneration,int);
  vtkGetMacro(AutomaticSphereGeneration,int);
  vtkBooleanMacro(AutomaticSphereGeneration,int);

  // Description:
  // Control how the texture coordinates are generated. If PreventSeam is
  // set, the s-coordinate ranges from 0->1 and 1->0 corresponding to the
  // theta angle variation between 0->180 and 180->0 degrees. Otherwise, the
  // s-ccordinate ranges from 0->1 between 0->360 degrees.
  vtkSetMacro(PreventSeam,int);
  vtkGetMacro(PreventSeam,int);
  vtkBooleanMacro(PreventSeam,int);

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

  void Execute();

  float Center[3];
  int AutomaticSphereGeneration;
  int PreventSeam;

};

#endif


