/***************************************************************************
   File:        SimScene.cpp                                                            
   Created:     02/04/2002                                                            
   Author:      Maxim Garber                                                
                Computer Science Department                                 
                University of North Carolina - Chapel Hill                  
                garber@cs.unc.edu                                           
                                                                            
   Description: Simulation scene file.                                                            
                                                                            
----------------------------------------------------------------------------.
   Copyright 2002 Maxim Garber                                              
                                   
                                                                            
                                                                            
*****************************************************************************/
#include "SimScene.h"
#include <algorithm>



/****************************************************************************
   Function   : SimScene                                          
   Description: Constructor                                                            
****************************************************************************/
SimScene::SimScene(char* fileName)
{
  FILE* fp = fopen(fileName,"r");
  if (fp==NULL) { printf("ERROR: unable to open SceneFile [%s]!\n",fileName); exit(1); }

  char  string[50];

  ///////////////////////////////////////////////////////////////////////////
  // Read Object Names
  fscanf(fp, "%s", &string);
  if(strcmp(string, "[scene]") != 0)
  { printf("ERROR: invalid ObjFile format [%s]!\n",fileName); exit(1); }

  // read next attribute
  fscanf(fp, "%s", &string);

  while(strcmp(string, "[end]") != 0)
  {
      if(strcmp(string, "cloth:") == 0)
      {
        char clothfile[50];
        fscanf(fp, "%s", &clothfile);
        SimCloth* cloth = new SimCloth(clothfile);
        _cloths.push_back(cloth);

      }

      if(strcmp(string, "sphere:") == 0)
      {
        char spherefile[50];
        fscanf(fp, "%s", &spherefile);
        SimSphere* sphere = new SimSphere(spherefile);
        _spheres.push_back(sphere);

      }
     
    // read next item
    fscanf(fp, "%s", &string);
  }

  
  // link clothes to collision spheres
  std::list<SimSphere*>::iterator s = _spheres.begin();
  for(; s!= _spheres.end(); s++)
  {
  
      std::list<SimCloth*>::iterator c = _cloths.begin();
      for(; c!= _cloths.end(); c++)
        (*c)->AddSphere(*s);
  }
}

/****************************************************************************
   Function   : ~SimScene                                         
   Description: Destructor                                                            
****************************************************************************/
SimScene::~SimScene()
{
  std::list<SimCloth*>::iterator i = _cloths.begin();
  for(; i!= _cloths.end(); i++)
      delete(*i);
  _cloths.clear();


  std::list<SimSphere*>::iterator j = _spheres.begin();
  for(; j!= _spheres.end(); j++)
      delete(*j);
  _spheres.clear();

}



/****************************************************************************
   Function   : Update                                            
   Description: Updates the objects in the scene                                                            
****************************************************************************/
void SimScene::Update(float timeStep)
{

  // update all spheres
  std::list<SimSphere*>::iterator j = _spheres.begin();
  for(; j!= _spheres.end(); j++)
  {
    (*j)->Update(timeStep);

    // handle intersphere collisions
    std::list<SimSphere*>::iterator s = j; 
    s++;
    float difference, delta[3];
    for(; s!= _spheres.end(); s++)
    {
      Subtract3fv(delta, (*j)->GetCenter(), (*s)->GetCenter());
      difference = (*j)->GetRadius() + (*s)->GetRadius() - Length3fv(delta);

      if(difference > 0)
      {  // we have a collision project objects to resolve collision
        float massFactor = (*j)->GetInverseMass();+(*s)->GetInverseMass();
        Normalize3fv(delta);

        float sDelta[3], jDelta[3];
         
        // move sphere s
        ScalarMult3fv(sDelta, delta, -difference*(*s)->GetInverseMass()/massFactor);
        (*s)->MoveCenter(sDelta);

        // move sphere j
        ScalarMult3fv(jDelta, delta,  difference*(*j)->GetInverseMass()/massFactor);
        (*j)->MoveCenter(jDelta);
        break;
      }
    }
  }

  // update all cloths
  std::list<SimCloth*>::iterator i = _cloths.begin();
  for(; i!= _cloths.end(); i++)
     (*i)->Update(timeStep);


  // cull inactive spheres
  std::list<SimSphere*>::iterator newEnd = std::stable_partition(_spheres.begin(), _spheres.end(), SimSphereActive);
  for(j = newEnd; j != _spheres.end(); j++)
  {
    SimSphere *sphere = *j;

    // remove sphere from cloth list
    std::list<SimCloth*>::iterator i = _cloths.begin();
    for(; i!= _cloths.end(); i++)
      (*i)->RemoveSphere(sphere);

    delete sphere;
  }
  if (newEnd != _spheres.end())
    _spheres.erase(newEnd, _spheres.end());
}


/****************************************************************************
   Function   : Draw                                              
   Description: Draws all of the objects in the scene                                                            
****************************************************************************/
void SimScene::Draw()
{
  // draw all spheres
  std::list<SimSphere*>::iterator j = _spheres.begin();
  for(; j!= _spheres.end(); j++)
      (*j)->Draw();

  // draw all cloths
  std::list<SimCloth*>::iterator i = _cloths.begin();
  for(; i!= _cloths.end(); i++)
     (*i)->Draw();
}


/****************************************************************************
   Function   : AddSphere                                         
   Description: Adds a sphere to the scene                                                            
****************************************************************************/
void SimScene::AddSphere(SimSphere* sphere)
{ 
  _spheres.push_back(sphere);
  std::list<SimCloth*>::iterator c = _cloths.begin();
  for(; c!= _cloths.end(); c++)
        (*c)->AddSphere(sphere);
}