/***************************************************************************
   File:        PBMCircleParticle.h                                                           
   Created:     03/31/2002                                                            
   Author:      Maxim Garber                                                
                Computer Science Department                                 
                University of North Carolina - Chapel Hill                  
                garber@cs.unc.edu                                           
                                                                            
   Description: A particle constrained to a circle.                                                           
                                                                            
----------------------------------------------------------------------------.
   Copyright 2002 Maxim Garber                                              
   UNC Collide Research Group                                               
                                                                            
                                                                            
*****************************************************************************/
#include "ODESolver.h"

class PBMCircleParticle
: public ODESystem
{
public:
  ////////////////////////////////////////////////////////////////////////////
  // constructor & destructor
  PBMCircleParticle(float center[2], float radius,  float theta, 
                    float mass,      float damping, ODESolver* solver);
  ~PBMCircleParticle();

  ////////////////////////////////////////////////////////////////////////////
  //simulation
  void Update(float timeStep);

  ////////////////////////////////////////////////////////////////////////////
  // ODE derivative
  virtual void ODEDerivative(const ODEConfig& config, float time, ODEConfig& derivative);

  ////////////////////////////////////////////////////////////////////////////
  // accessors
  void         GetParticlePosition(float& x, float& y);
  void         GetCircleCenter    (float& x, float& y){x = _center[0]; x = _center[1];}
  float        GetCircleRadius    (){return _radius;}
  float        GetMass            (){return _mass;  }
  float        GetTheta           (){return _theta; }

  ////////////////////////////////////////////////////////////////////////////
  // mutators
  void SetCircleCenter (float center[2]    ){_center[0] = center[0]; _center[1] = center[1];}
  void SetCircleRadius (float radius       ){_radius = radius;                              }
  void AddForce        (float force[2]     ){_force[0] += force[0]; _force[1] += force[1];  }
  void SetSolver       (ODESolver* solver  ){_solver = solver;                              }
  void SetDamping      (float dampingFactor){_dampingFactor = dampingFactor;                }
  void SetMass         (float mass         ){_mass = mass;                                  }

  ////////////////////////////////////////////////////////////////////////////
  // rendering
  void Draw();

private:
  // circle position and radius
  float _center[2];
  float _radius;

  // particle location and angular velocity
  float _theta;
  float _thetaDot;

  // physical properties
  float _mass;
  float _dampingFactor;
  
  // force on particle in euclidean space
  float _force[2];

  // ordinary differential equation solver
  ODESolver* _solver;
};