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

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkDecimatePro.h,v $
  Language:  C++
  Date:      $Date: 2001/11/13 14:13:49 $
  Version:   $Revision: 1.49 $


Copyright (c) 1993-2001 Ken Martin, Will Schroeder, Bill Lorensen 
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.

 * Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

 * 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.

 * Modified source versions must be plainly marked as such, and must not be
   misrepresented as being the original software.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

=========================================================================*/
// .NAME vtkDecimatePro - reduce the number of triangles in a mesh
// .SECTION Description
// vtkDecimatePro is a filter to reduce the number of triangles in a triangle 
// mesh, forming a good approximation to the original geometry. The input to 
// vtkDecimatePro is a vtkPolyData object, and only triangles are treated. If 
// you desire to decimate polygonal meshes, first triangulate the polygons
// with vtkTriangleFilter object.
// 
// The implementation of vtkDecimatePro is similar to the algorithm
// originally described in "Decimation of Triangle Meshes", Proc Siggraph
// `92, with three major differences. First, this algorithm does not
// necessarily preserve the topology of the mesh. Second, it is guaranteed to
// give the a mesh reduction factor specified by the user (as long as certain
// constraints are not set - see Caveats). Third, it is set up generate
// progressive meshes, that is a stream of operations that can be easily
// transmitted and incrementally updated (see Hugues Hoppe's Siggraph '96
// paper on progressive meshes).
// 
// The algorithm proceeds as follows. Each vertex in the mesh is classified
// and inserted into a priority queue. The priority is based on the error to
// delete the vertex and retriangulate the hole. Vertices that cannot be
// deleted or triangulated (at this point in the algorithm) are
// skipped. Then, each vertex in the priority queue is processed (i.e.,
// deleted followed by hole triangulation using edge collapse). This
// continues until the priority queue is empty. Next, all remaining vertices
// are processed, and the mesh is split into separate pieces along sharp
// edges or at non-manifold attachment points and reinserted into the
// priority queue. Again, the priority queue is processed until empty. If
// the desired reduction is still not achieved, the remaining vertices are
// split as necessary (in a recursive fashion) so that it is possible to
// eliminate every triangle as necessary.
// 
// To use this object, at a minimum you need to specify the ivar
// TargetReduction. The algorithm is guaranteed to generate a reduced mesh
// at this level as long as the following four conditions are met: 1)
// topology modification is allowed (i.e., the ivar PreserveTopology is off);
// 2) mesh splitting is enabled (i.e., the ivar Splitting is on); 3) the
// algorithm is allowed to modify the boundary of the mesh (i.e., the ivar
// BoundaryVertexDeletion is on); and 4) the maximum allowable error (i.e.,
// the ivar MaximumError) is set to VTK_LARGE_FLOAT.  Other important
// parameters to adjust include the FeatureAngle and SplitAngle ivars, since
// these can impact the quality of the final mesh. Also, you can set the
// ivar AccumulateError to force incremental error update and distribution
// to surrounding vertices as each vertex is deleted. The accumulated error
// is a conservative global error bounds and decimation error, but requires
// additional memory and time to compute.

// .SECTION Caveats
// To guarantee a given level of reduction, the ivar PreserveTopology must
// be off; the ivar Splitting is on; the ivar BoundaryVertexDeletion is on;
// and the ivar MaximumError is set to VTK_LARGE_FLOAT.
//
// If PreserveTopology is off, and SplitEdges is off; the mesh topology may
// be modified by closing holes.
//
// Once mesh splitting begins, the feature angle is set to the split angle.

// .SECTION See Also
// vtkDecimate vtkQuadricClustering vtkQuadricDecimation


#ifndef __vtkDecimatePro_h
#define __vtkDecimatePro_h

#include "vtkPolyDataToPolyDataFilter.h"
#include "vtkPriorityQueue.h"

// Special structures for building loops
typedef struct _vtkProLocalVertex 
  {
  vtkIdType     id;
  float   x[3];
  float   FAngle;
  } vtkProLocalVertex, *vtkProLocalVertexPtr;
    
typedef struct _vtkProLocalTri
  {
  vtkIdType     id;
  float   area;
  float   n[3];
  vtkIdType     verts[3];
  } vtkProLocalTri, *vtkProLocalTriPtr;

//
// Special classes for manipulating data
//
//BTX - begin tcl exclude
//
class vtkProVertexArray { //;prevent man page generation
public:
  vtkProVertexArray(const vtkIdType sz) 
    {this->MaxId = -1; this->Array = new vtkProLocalVertex[sz];};
  ~vtkProVertexArray()
    {
    if (this->Array)
      {
      delete [] this->Array;
      }
    };
  vtkIdType GetNumberOfVertices() {return this->MaxId + 1;};
  void InsertNextVertex(vtkProLocalVertex& v) 
    {this->MaxId++; this->Array[this->MaxId] = v;};
  vtkProLocalVertex& GetVertex(vtkIdType i) {return this->Array[i];};
  void Reset() {this->MaxId = -1;};

  vtkProLocalVertex *Array; // pointer to data
  vtkIdType MaxId;             // maximum index inserted thus far
};

class vtkProTriArray { //;prevent man page generation
public:
  vtkProTriArray(const vtkIdType sz) 
    {this->MaxId = -1; this->Array = new vtkProLocalTri[sz];};
  ~vtkProTriArray()
    {
      if (this->Array)
        {
        delete [] this->Array;
        }
    };
  vtkIdType GetNumberOfTriangles() {return this->MaxId + 1;};
  void InsertNextTriangle(vtkProLocalTri& t) 
    {this->MaxId++; this->Array[this->MaxId] = t;};
  vtkProLocalTri& GetTriangle(vtkIdType i) {return this->Array[i];};
  void Reset() {this->MaxId = -1;};

  vtkProLocalTri *Array;  // pointer to data
  vtkIdType MaxId;           // maximum index inserted thus far
};
//ETX - end tcl exclude
//


class VTK_GRAPHICS_EXPORT vtkDecimatePro : public vtkPolyDataToPolyDataFilter
{
public:
  vtkTypeMacro(vtkDecimatePro,vtkPolyDataToPolyDataFilter);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Create object with specified reduction of 90% and feature angle of
  // 15 degrees. Edge splitting is on, defer splitting is on, and the
  // split angle is 75 degrees. Topology preservation is off, delete
  // boundary vertices is on, and the maximum error is set to
  // VTK_LARGE_FLOAT. The inflection point ratio is 10 and the vertex
  // degree is 25. Error accumulation is turned off.
  static vtkDecimatePro *New();

  // Description:
  // Specify the desired reduction in the total number of polygons. Because
  // of various constraints, this level of reduction may not be realized. If
  // you want to guarantee a particular reduction, you must turn off 
  // PreserveTopology and BoundaryVertexDeletion, turn on SplitEdges,
  // and set the MaximumError to VTK_LARGE_FLOAT (these ivars are initialized 
  // this way when the object is instantiated).
  vtkSetClampMacro(TargetReduction,float,0.0,1.0);
  vtkGetMacro(TargetReduction,float);

  // Description:
  // Turn on/off whether to preserve the topology of the original mesh. If
  // on, mesh splitting and hole elimination will not occur. This may limit
  // the maximum reduction that may be achieved.
  vtkSetMacro(PreserveTopology,int);
  vtkGetMacro(PreserveTopology,int);
  vtkBooleanMacro(PreserveTopology,int);

  // Description:
  // Specify the mesh feature angle. This angle is used to define what
  // an edge is (i.e., if the surface normal between two adjacent triangles
  // is >= FeatureAngle, an edge exists).
  vtkSetClampMacro(FeatureAngle,float,0.0,180.0);
  vtkGetMacro(FeatureAngle,float);

  // Description:
  // Turn on/off the splitting of the mesh at corners, along edges, at
  // non-manifold points, or anywhere else a split is required. Turning 
  // splitting off will better preserve the original topology of the
  // mesh, but you may not obtain the requested reduction.
  vtkSetMacro(Splitting,int);
  vtkGetMacro(Splitting,int);
  vtkBooleanMacro(Splitting,int);

  // Description:
  // Specify the mesh split angle. This angle is used to control the splitting
  // of the mesh. A split line exists when the surface normals between
  // two edge connected triangles are >= SplitAngle.
  vtkSetClampMacro(SplitAngle,float,0.0,180.0);
  vtkGetMacro(SplitAngle,float);

  // Description:
  // In some cases you may wish to split the mesh prior to algorithm
  // execution. This separates the mesh into semi-planar patches, which are
  // disconnected from each other. This can give superior results in some
  // cases. If the ivar PreSplitMesh ivar is enabled, the mesh is split with
  // the specified SplitAngle. Otherwise mesh splitting is deferred as long
  // as possible.
  vtkSetMacro(PreSplitMesh,int);
  vtkGetMacro(PreSplitMesh,int);
  vtkBooleanMacro(PreSplitMesh,int);

  // Description:
  // Set the largest decimation error that is allowed during the decimation
  // process. This may limit the maximum reduction that may be achieved. The
  // maximum error is specified as a fraction of the maximum length of
  // the input data bounding box.
  vtkSetClampMacro(MaximumError,float,0.0,VTK_LARGE_FLOAT);
  vtkGetMacro(MaximumError,float);

  // Description:
  // The computed error can either be computed directly from the mesh
  // or the error may be accumulated as the mesh is modified. If the error
  // is accumulated, then it represents a global error bounds, and the ivar
  // MaximumError becomes a global bounds on mesh error. Accumulating the
  // error requires extra memory proportional to the number of vertices in
  // the mesh. If AccumulateError is off, then the error is not accumulated.
  vtkSetMacro(AccumulateError,int);
  vtkGetMacro(AccumulateError,int);
  vtkBooleanMacro(AccumulateError,int);

  // Description:
  // The MaximumError is normally defined as a fraction of the dataset bounding
  // diagonal. By setting ErrorIsAbsolute to 1, the error is instead defined
  // as that specified by AbsoluteError. By default ErrorIsAbsolute=0.
  vtkSetMacro(ErrorIsAbsolute,int);
  vtkGetMacro(ErrorIsAbsolute,int);

  // Description:
  // Same as MaximumError, but to be used when ErrorIsAbsolute is 1
  vtkSetClampMacro(AbsoluteError,float,0.0,VTK_LARGE_FLOAT);
  vtkGetMacro(AbsoluteError,float);

  // Description:
  // Turn on/off the deletion of vertices on the boundary of a mesh. This
  // may limit the maximum reduction that may be achieved.
  vtkSetMacro(BoundaryVertexDeletion,int);
  vtkGetMacro(BoundaryVertexDeletion,int);
  vtkBooleanMacro(BoundaryVertexDeletion,int);

  // Description:
  // If the number of triangles connected to a vertex exceeds "Degree", then
  // the vertex will be split. (NOTE: the complexity of the triangulation
  // algorithm is proportional to Degree^2. Setting degree small can improve
  // the performance of the algorithm.)
  vtkSetClampMacro(Degree,int,25,VTK_CELL_SIZE);
  vtkGetMacro(Degree,int);
  
  // Description:
  // Specify the inflection point ratio. An inflection point occurs
  // when the ratio of reduction error between two iterations is greater
  // than or equal to the InflectionPointRatio.
  vtkSetClampMacro(InflectionPointRatio,float,1.001,VTK_LARGE_FLOAT);
  vtkGetMacro(InflectionPointRatio,float);


  // Description:
  // Get the number of inflection points. Only returns a valid value after
  // the filter has executed.  The values in the list are mesh reduction
  // values at each inflection point. Note: the first inflection point always
  // occurs right before non-planar triangles are decimated (i.e., as the
  // error becomes non-zero).
  vtkIdType GetNumberOfInflectionPoints();

  // Description:
  // Get a list of inflection points. These are float values 0 < r <= 1.0 
  // corresponding to reduction level, and there are a total of
  // NumberOfInflectionPoints() values. You must provide an array (of
  // the correct size) into which the inflection points are written.
  void GetInflectionPoints(float *inflectionPoints);

  // Description:
  // Get a list of inflection points. These are float values 0 < r <= 1.0 
  // corresponding to reduction level, and there are a total of
  // NumberOfInflectionPoints() values. You must provide an array (of
  // the correct size) into which the inflection points are written.
  // This method returns a pointer to a list of inflection points.
  float *GetInflectionPoints();

protected:
  vtkDecimatePro();
  ~vtkDecimatePro();

  void Execute();

  float TargetReduction;
  float FeatureAngle;
  float MaximumError;
  float AbsoluteError;
  int ErrorIsAbsolute;
  int AccumulateError;
  float SplitAngle;
  int Splitting;
  int PreSplitMesh;
  int BoundaryVertexDeletion;
  int PreserveTopology;
  int Degree;
  float InflectionPointRatio;
  vtkFloatArray *InflectionPoints;

  // to replace a static object
  vtkIdList *Neighbors;
  vtkPriorityQueue *EdgeLengths;

  void SplitMesh();
  int EvaluateVertex(vtkIdType ptId, unsigned short int numTris,
                     vtkIdType *tris, vtkIdType fedges[2]);
  vtkIdType FindSplit(int type, vtkIdType fedges[2], vtkIdType& pt1,
                      vtkIdType& pt2, vtkIdList *CollapseTris);
  int IsValidSplit(int index);
  void SplitLoop(vtkIdType fedges[2], vtkIdType& n1, vtkIdType *l1,
                 vtkIdType& n2, vtkIdType *l2);
  void SplitVertex(vtkIdType ptId,int type, unsigned short int numTris,
                   vtkIdType *tris, int insert);
  int CollapseEdge(int type, vtkIdType ptId, vtkIdType collapseId,
                   vtkIdType pt1, vtkIdType pt2, vtkIdList *CollapseTris);
  void DistributeError(float error);

private:
  void InitializeQueue(vtkIdType numPts);
  void DeleteQueue()
    {
      if (this->Queue)
      {
       this->Queue->Delete();
      }
      this->Queue=NULL;};
  void Insert(vtkIdType id, float error= -1.0);
  int Pop(float &error);
  float DeleteId(vtkIdType id) {return this->Queue->DeleteId(id);};
  void Reset() {this->Queue->Reset();};

  vtkPriorityQueue *Queue;
  vtkFloatArray *VertexError;

  vtkProVertexArray *V;
  vtkProTriArray *T;

  // Use to be static variables used by object
  vtkPolyData *Mesh; //operate on this data structure
  float Pt[3];      //least squares plane point
  float Normal[3];  //least squares plane normal
  float LoopArea;   //the total area of all triangles in a loop
  float CosAngle;   //Cosine of dihedral angle
  float Tolerance;  //Intersection tolerance
  float X[3];       //coordinates of current point
  int NumCollapses; //Number of times edge collapses occur
  int NumMerges;    //Number of times vertex merges occur
  int Split;        //Controls whether and when vertex splitting occurs
  int VertexDegree; //Maximum number of triangles that can use a vertex
  vtkIdType NumberOfRemainingTris; //Number of triangles left in the mesh
  float TheSplitAngle; //Split angle
  int SplitState;   //State of the splitting process
  float Error;      //Maximum allowable surface error

private:
  vtkDecimatePro(const vtkDecimatePro&);  // Not implemented.
  void operator=(const vtkDecimatePro&);  // Not implemented.
};

#endif


