#ifndef __SIMCLOTH_H__
#define __SIMCLOTH_H__
/***************************************************************************
   File:        SimCloth.h                                                            
   Created:     01/22/02                                                            
   Author:      Maxim Garber                                                
                Computer Science Department                                 
                University of North Carolina - Chapel Hill                  
                garber@cs.unc.edu                                           
                                                                            
   Description: Cloth simulation class.                                                           
                                                                            
----------------------------------------------------------------------------.
   Copyright 2002 Maxim Garber                                              
                                                                            
                                                                            
*****************************************************************************/
#include "SimSphere.h"
#include "vec3fv.hpp"
#include <list>

class SimCloth
{
public:

   /*****************************************************************************
      Constructors & Destructor
   *****************************************************************************/
   SimCloth(const char* file_name);
   
   ~SimCloth();

   /*****************************************************************************
      Accessors
   *****************************************************************************/
   unsigned int  GetRows()            const {return _rows;            }
   unsigned int  GetCols()            const {return _cols;            }
   float         GetHorizStrutLength()const {return _horizStrutLength;}
   float         GetVertStrutLength() const {return _vertStrutLength; }
   float         GetDiagStrutLength() const {return _diagStrutLength; }
   float         GetPointInverseMass()const {return _pointInverseMass; }

   /*****************************************************************************
      Control Point Management
   *****************************************************************************/
   const float* GetControlPoint(unsigned int row, unsigned int col) const
                      {return &_pControlPoints[3*(col+row*_cols)];}
   
   void  SetControlPoint(unsigned int col, unsigned int row, const float position[3])
   {
     Copy3fv(&_pControlPoints[3*(col+row*_cols)], position);
     Copy3fv(&_pOldControlPoints[3*(col+row*_cols)], position);
   }

   unsigned char GetIsFree(const unsigned int col, const unsigned int row) const
                      {return _pIsFree[col+row*_cols];}

   void  SetIsFree(const unsigned int col, const unsigned int row, const unsigned char isFree)
                      {_pIsFree[col+row*_cols] = isFree;}

   /*****************************************************************************
      Collision with Spheres
   *****************************************************************************/
   void AddSphere   (SimSphere* sphere) {_pSpheres.push_back(sphere);}
   void RemoveSphere(SimSphere* sphere) {_pSpheres.remove(sphere);}

   /*****************************************************************************
      Drawing
   *****************************************************************************/
   void Draw()      const;
   
   /*****************************************************************************
      Mesh Tightness
   *****************************************************************************/
   void ChangeTightness(float multiplier);


   /*****************************************************************************
      Cloth Simulation
   *****************************************************************************/
   void Update(const float timeStep);       // timeStep in seconds

private:
   // cloth constriant struts
   float               _horizStrutLength;  // horizontal strut length
   float               _vertStrutLength;   // vertical strut length
   float               _diagStrutLength;   // diagonal strut length
   float               _horizStrutLength2; // squared horizontal strut length
   float               _vertStrutLength2;  // squared vertical strut length
   float               _diagStrutLength2;  // squared diagonal strut length

   // cloth control points
   float              *_pControlPoints;    // current control point positions
   float              *_pOldControlPoints; // previous control point positions
   unsigned char      *_pIsFree;           // equals 1 if corresponding control points is movable, 0 otherwise
   float               _pointInverseMass;  // 1/(mass of a control point in kg)
   unsigned int        _rows;              // rows in control grid
   unsigned int        _cols;              // cols in control grid

   // initial state
   float              _centerPoint[3];
   unsigned int       _hIndex;
   unsigned int       _vIndex;
   float              _width; 
   float              _height;


   // rendering
   float               *_pNormals;          // normal vectors for smooth shading
   bool                 _reverseNormals;
   unsigned char        _color[3];

   // for cloth simulation
   float               _timeStep;          // length of last time step
   float               _gravity[3];           // force of gravity
   float               _dampingFactor;     // amount of damping (air resistance)
   unsigned int        _numIterations;     // number of iterations of relaxation step

   // collision detection
   std::list<SimSphere*> _pSpheres;        // pointer to collision spheres
  
   // texture file
   bool           _textured;
   char           _texFile[50];
   unsigned int   _texTileWidth;
   unsigned int   _texTileHeight;
   unsigned char *_pTexture;
   int            _texWidth;
   int            _texHeight;
   int            _texChannels;
   unsigned int   _texName;


   void _ReadParameterFile(const char* file_name);

   /*****************************************************************************
      Cloth Simulation Helper Functions
   *****************************************************************************/
   void _InitializeSimulation();
   void _Integrate();
   void _SatisfyConstraints();

   /*****************************************************************************
      Rendering Helper Functions
   *****************************************************************************/
   void _ComputeNormals();

   // Inline Helpers
   // Avoid using these to traverse the data structures. 
   // Its better to use pointer incrementing.
   float* _GetControlPoint(unsigned int col, unsigned int row)
   {
      return _pControlPoints + 3*(col + row*_cols);
   }

   float* _GetOldControlPoint(unsigned int col, unsigned int row)
   {
      return _pOldControlPoints + 3*(col + row*_cols);
   }
   
   
   unsigned char _GetIsFree(unsigned int col, unsigned int row)
   {
      return _pIsFree[col + row*_cols];
   }
};

#endif //__SIMCLOTH_H__