source: orxonox.OLD/orxonox/branches/shadows/src/world.cc @ 3760

/* 
   orxonox - the future of 3D-vertical-scrollers

   Copyright (C) 2004 orx

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   ### File Specific:
   main-programmer: Patrick Boenzli
   co-programmer: Christian Meyer
*/

#include "world.h"
#include "world_entity.h"
#include "collision.h"
#include "track_manager.h"
#include "track.h"
#include "player.h"
#include "command_node.h"
#include "camera.h"
#include "environment.h"
#include "p_node.h"
#include "null_parent.h"
#include "helper_parent.h"
#include "glmenu_imagescreen.h"
#include "importer/material.h"

using namespace std;


/** 
    \brief create a new World
    
    This creates a new empty world!
*/
World::World (char* name)
{
  this->setClassName ("World");
  this->worldName = name;
  this->debugWorldNr = -1;
  this->entities = new tList<WorldEntity>();
  
}

World::World (int worldID)
{
  this->debugWorldNr = worldID;
  this->worldName = NULL;
  this->entities = new tList<WorldEntity>();
}

/** 
    \brief remove the World from memory
    
    delete everything explicitly, that isn't contained in the parenting tree!
    things contained in the tree are deleted automaticaly
*/
World::~World ()
{
  printf("World::~World() - deleting current world\n");
  CommandNode* cn = Orxonox::getInstance()->getLocalInput();
  cn->unbind(this->localPlayer);
  cn->reset();
  this->localCamera->destroy();

  this->nullParent->destroy ();

  //delete this->trackManager;

  /*
  WorldEntity* entity = entities->enumerate();  
  while( entity != NULL ) 
    { 
      entity->destroy();
      entity = entities->nextElement();
    }
  this->entities->destroy();
  */

  /* FIX the parent list has to be cleared - not possible if we got the old list also*/


  //delete this->entities;
  //delete this->localCamera;
  /* this->localPlayer hasn't to be deleted explicitly, it is 
     contained in entities*/
}

GLfloat ctrlpoints[4][3] = {
  {20.0, 10.0, 5.0}, {40.0, -10.0, 0.0},
  {60.0, -10.0, 5.0}, {80.0, 10.0, 5.0}};




ErrorMessage World::init()
{
  this->bPause = false;
  CommandNode* cn = Orxonox::getInstance()->getLocalInput();
  cn->addToWorld(this);
  cn->enable(true);

  //glMap1f (GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ctrlpoints[0][0]);
  //glEnable (GL_MAP1_VERTEX_3);
  
  //theNurb = gluNewNurbsRenderer ();
  //gluNurbsProperty (theNurb, GLU_NURBS_MODE, GLU_NURBS_TESSELLATOR);
  //gluNurbsProperty (theNurb, GLU_NURBS_VERTEX, vertexCallback );

}



ErrorMessage World::start()
{
  printf("World::start() - starting current World: nr %i\n", this->debugWorldNr);
  this->bQuitOrxonox = false;
  this->bQuitCurrentGame = false;
  this->mainLoop();
}

ErrorMessage World::stop()
{
  printf("World::stop() - got stop signal\n");
  this->bQuitCurrentGame = true;
}

ErrorMessage World::pause()
{
  this->isPaused = true;
}


ErrorMessage World::resume()
{
  this->isPaused = false;
}


void World::destroy()
{
}


void World::displayLoadScreen ()
{
  printf ("World::displayLoadScreen - start\n"); 
  
  //GLMenuImageScreen* 
  this->glmis = new GLMenuImageScreen();
  this->glmis->init();
  this->glmis->setMaximum(10);
  this->glmis->draw();
 
  printf ("World::displayLoadScreen - end\n"); 
}


void World::releaseLoadScreen ()
{
  printf ("World::releaseLoadScreen - start\n"); 
  this->glmis->setValue(this->glmis->getMaximum());
  SDL_Delay(500);
  printf ("World::releaseLoadScreen - end\n"); 
}


void World::load()
{
  //  BezierCurve* tmpCurve = new BezierCurve();
  if(this->debugWorldNr != -1)
    {
      trackManager = TrackManager::getInstance();
      trackManager->addPoint(Vector(0,-5,0));
      trackManager->addPoint(Vector(10,0,5));
      trackManager->addPoint(Vector(20,0,-5));
      trackManager->addPoint(Vector(30,0,5));
      trackManager->addPoint(Vector(40,0,5));
      trackManager->setDuration(.5);
      trackManager->setSavePoint();
      trackManager->addPoint(Vector(50,10,10));
      trackManager->addPoint(Vector(60,0, 10));
      trackManager->addPoint(Vector(70,0, 10));
      trackManager->addPoint(Vector(80,0,-10));
      trackManager->addPoint(Vector(90,0,-10));
      trackManager->setDuration(.5);
      trackManager->setSavePoint();
      trackManager->addPoint(Vector(110,0,5));
      trackManager->addPoint(Vector(120,0, 10));
      trackManager->addPoint(Vector(130,0, 10));
      trackManager->addPoint(Vector(140,0,-10));
      trackManager->addPoint(Vector(150,0,-10));
      trackManager->setDuration(.5);
      int fork11, fork12, fork13, fork14;
      trackManager->fork(4, &fork11, &fork12, &fork13, &fork14);
      trackManager->workOn(fork11);
      trackManager->addPoint(Vector(170, 0, -15));
      trackManager->addPoint(Vector(180, 0, -15));
      trackManager->workOn(fork12);
      trackManager->addPoint(Vector(170, 0, 10));
      trackManager->addPoint(Vector(180, 0, 10));
      trackManager->addPoint(Vector(190,2,5));
      trackManager->addPoint(Vector(200,2,5));
      int fork21, fork22;
      trackManager->fork(2, &fork21, &fork22);
      trackManager->workOn(fork21);
      trackManager->addPoint(Vector(220, 10,-10));
      trackManager->addPoint(Vector(230, 0,-10));
      trackManager->addPoint(Vector(240, 0, 2));
      trackManager->addPoint(Vector(250, 0, 0));
      trackManager->addPoint(Vector(260, 0, 5));
      trackManager->join(2, fork12, fork11);
      trackManager->workOn(fork22);
      trackManager->addPoint(Vector(220, -10,10));
      trackManager->addPoint(Vector(230, 0, 10));
      trackManager->addPoint(Vector(240, 0, 10));
      trackManager->addPoint(Vector(250, 0, 5));
      trackManager->workOn(fork13);
      trackManager->addPoint(Vector(200,-10,5));
      trackManager->addPoint(Vector(250,-10,5));
      printf("fork14: %d\n", fork14);
      trackManager->workOn(fork14);
      trackManager->addPoint(Vector(200,15,0));
      trackManager->addPoint(Vector(210,0,10));



      trackManager->join(4, fork21, fork22, fork13, fork14);

      /*monitor progress*/
      this->glmis->step();

      /*
      tmpCurve->addNode(Vector(10,0,-10));
      //tmpCurve->addNode(Vector(10,2,5));
      //tmpCurve->addNode(Vector(10,3,-5));
      //      tmpCurve->addNode(Vector(10,1,5));
      tmpCurve->addNode(Vector(10,0,5));
      */
      switch(this->debugWorldNr)
        {
          /*
            this loads the hard-coded debug world. this only for simplicity and will be 
            removed by a reald world-loader, which interprets a world-file.
            if you want to add an own debug world, just add a case DEBUG_WORLD_[nr] and
            make whatever you want...
           */
        case DEBUG_WORLD_0:
          {
            this->nullParent = NullParent::getInstance ();
            this->nullParent->setName ("NullParent");

            // create some path nodes
            this->pathnodes = new Vector[6];
            this->pathnodes[0] = Vector(0, 0, 0);
            this->pathnodes[1] = Vector(1000, 0, 0);
            //      this->pathnodes[2] = Vector(-100, 140, 0);
            //      this->pathnodes[3] = Vector(0, 180, 0);
            //      this->pathnodes[4] = Vector(100, 140, 0);
            //      this->pathnodes[5] = Vector(100, 40, 0);
            
            // create the tracks
            this->tracklen = 2;
            this->track = new Track[2];
            for( int i = 0; i < this->tracklen; i++)
              {
                this->track[i] = Track( i, (i+1)%this->tracklen, &this->pathnodes[i], &this->pathnodes[(i+1)%this->tracklen]);
              }
            // !\todo old track-system has to be removed

            //create helper for player
            HelperParent* hp = new HelperParent ();
            /* the player has to be added to this helper */

            // create a player
            WorldEntity* myPlayer = new Player ();
            myPlayer->setName ("player");
            this->spawn (myPlayer);
            this->localPlayer = myPlayer;

            /*monitor progress*/
            this->glmis->step();            

            // bind input
            Orxonox *orx = Orxonox::getInstance ();
            orx->getLocalInput()->bind (myPlayer);
            
            
            //create shadow
            
            this->shadow =new Shadow(myPlayer->model,(Player*)myPlayer);            
            //shadow->init();      
            first=true;             
            
            //create skysphere
            this->skysphere =new Skysphere();
            
            
            // bind camera
            this->localCamera = new Camera(this);
            this->localCamera->setName ("camera");
            this->getCamera()->bind (myPlayer);
            this->localPlayer->addChild (this->localCamera);

            /*monitor progress*/
            this->glmis->step();

            Vector* es = new Vector (50, 2, 0);
            Quaternion* qs = new Quaternion ();
            WorldEntity* env = new Environment();
            env->setName ("env");
            this->spawn(env, es, qs);
           
            /*monitor progress*/
            this->glmis->step();

            break;
          }
        case DEBUG_WORLD_1:
          {
            /*
            this->testCurve = new UPointCurve();
            this->testCurve->addNode(Vector( 0, 0, 0));
            this->testCurve->addNode(Vector(10, 0, 5));
            this->testCurve->addNode(Vector(20, -5,-5));
            this->testCurve->addNode(Vector(30, 5, 10));
            this->testCurve->addNode(Vector(40, 0,-10));
            this->testCurve->addNode(Vector(50, 0,-10));
            */

            this->nullParent = NullParent::getInstance ();
            this->nullParent->setName ("NullParent");

            // create some path nodes
            this->pathnodes = new Vector[6];
            this->pathnodes[0] = Vector(0, 0, 0);
            this->pathnodes[1] = Vector(20, 10, 10);
            this->pathnodes[2] = Vector(40, 0, 10);
            this->pathnodes[3] = Vector(60, 10, 0);
            this->pathnodes[4] = Vector(80, 20, 10);
            this->pathnodes[5] = Vector(30, 50, 0);
            
            


            // create the tracks
            this->tracklen = 6;
            this->track = new Track[6];
            for( int i = 0; i < this->tracklen; i++)
              {
                this->track[i] = Track( i, (i+1)%this->tracklen, &this->pathnodes[i], &this->pathnodes[(i+1)%this->tracklen]);
              }

            // create a player
            WorldEntity* myPlayer = new Player();
            myPlayer->setName ("player");
            this->spawn(myPlayer);
            this->localPlayer = myPlayer;           
            
            // bind input
            Orxonox *orx = Orxonox::getInstance();
            orx->getLocalInput()->bind (myPlayer);
            
            // bind camera
            this->localCamera = new Camera (this);
            this->localCamera->setName ("camera");
            this->getCamera()->bind (myPlayer); 
            this->localPlayer->addChild (this->localCamera);
            break;
          }
        default:
          printf("World::load() - no world with ID %i found", this->debugWorldNr );
        }
    }
  else if(this->worldName != NULL)
    {

    }

  // initialize debug coord system
  
        objectList = glGenLists(1);
        glNewList (objectList, GL_COMPILE);
        glLoadIdentity();
        //glColor3f(1.0,0,0);
  
        // Enabling Textures
        glEnable(GL_TEXTURE_2D);
  
        // Selecting the new Ground Material.
        
    
  
  
    
 
  // Initializing the Ground, and loading a Texture into it.
  Material* boden = new Material("Ground");
  boden->setDiffuseMap("../data/pictures/ground.tga");
  // Setting the illumination mode otherwise it is flat-shaded.
  boden->setIllum(3);
  boden->select();
  int sizeX = 100;
  int sizeZ = 80;
  float length = 1000;
  float width = 300;
  float widthX = float (length /sizeX);
  float widthZ = float (width /sizeZ);
  
  float 
  
  height [sizeX][sizeZ];
  Vector normal_vectors[sizeX][sizeZ];
  Vector vertexes[sizeX][sizeZ];
  
  glBegin(GL_QUADS);
  
  
  for ( int i = 0; i<sizeX-1; i+=1)
    for (int j = 0; j<sizeZ-1;j+=1)
      //height[i][j] = rand()/20046 + (j-25)*(j-25)/30;
#ifdef __WIN32__
      height[i][j]=(sin((float)j/3)*rand()*i/182400)*.5;
#else
      height[i][j]=(sin((float)j/3)*rand()*(long)i/6282450500.0)*.5;
#endif

  //Die Huegel ein wenig glaetten
  for (int h=1; h<2;h++)
    for (int i=1;i<sizeX-2 ;i+=1 )
      for(int j=1;j<sizeZ-2;j+=1)
        height[i][j]=(height[i+1][j]+height[i][j+1]+height[i-1][j]+height[i][j-1])/4;
  
  //Berechnung von normalen Vektoren
  for(int i=1;i<sizeX-2;i+=1)
    for(int j=1;j<sizeZ-2 ;j+=1)
      {
        Vector v1 = Vector (widthX*(1),      height[i][j],      widthZ*(j) );
        Vector v2 = Vector (widthX*(i-1),    height[i-1][j],    widthZ*(j));
        Vector v3 = Vector (widthX*(i),      height[i][j+1],    widthZ*(j+1));
        Vector v4 = Vector (widthX*(i+1),    height[i+1][j],    widthZ*(j));
        Vector v5 = Vector (widthX*(i),      height[i][j-1],    widthZ*(j-1));
        
        Vector c1 = v2 - v1;
        Vector c2 = v3 - v1;
        Vector c3=  v4 - v1;
        Vector c4 = v5 - v1;
        Vector zero = Vector (0,0,0);
        normal_vectors[i][j]=c1.cross(v3-v5)+c2.cross(v4-v2)+c3.cross(v5-v3)+c4.cross(v2-v4);
        normal_vectors[i][j].normalize();
        shadow->setNormal(normal_vectors[i][j],i,j);
      }
      
      
       
  for ( int i = 0; i<sizeX; i+=1)
    for (int j = 0; j<sizeZ;j+=1)
      {   
        Vector v1 = Vector (widthX*(i),      height[i][j]-20,       widthZ*(j)  -width/2);
        Vector v2 = Vector (widthX*(i+1),    height[i+1][j]-20,     widthZ*(j)  -width/2);
        Vector v3 = Vector (widthX*(i+1),    height[i+1][j+1]-20,   widthZ*(j+1)-width/2);
        Vector v4 = Vector (widthX*(i),      height[i][j+1]-20,     widthZ*(j+1)-width/2);
        float a[3];
        a[0]=.8;
        a[1]=.8;
        a[2]=.8;
        glMaterialfv(GL_FRONT,GL_DIFFUSE,a);
        shadow->setVertexNum(v1,i,j,0);
        shadow->setVertexNum(v2,i,j,1);
        shadow->setVertexNum(v3,i,j,2);
        shadow->setVertexNum(v4,i,j,3);
        
                        
        
        glNormal3f(normal_vectors[i][j].x, normal_vectors[i][j].y, normal_vectors[i][j].z);
        glTexCoord2f(0.0f,0.0f);
        //glTexCoord2f((float)i/(float)sizeX,(float)j/(float)sizeZ);
        glVertex3f(v1.x, v1.y, v1.z);
        
        glNormal3f(normal_vectors[i+1][j].x, normal_vectors[i+1][j].y, normal_vectors[i+1][j].z);
        glTexCoord2f(1.0f,0.0f);
        //glTexCoord2f((float)(i+1.0)/(float)sizeX,(float)j/(float)sizeZ);
        glVertex3f(v2.x, v2.y, v2.z);
        
        glNormal3f(normal_vectors[i+1][j+1].x, normal_vectors[i+1][j+1].y, normal_vectors[i+1][j+1].z);
        glTexCoord2f(1.0f,1.0f);
        //glTexCoord2f((float)(i+1.0)/(float)sizeX,(float)(j+1.0)/(float)sizeZ);
        glVertex3f(v3.x, v3.y, v3.z);
        
        glNormal3f(normal_vectors[i][j+1].x, normal_vectors[i][j+1].y, normal_vectors[i][j+1].z);
        glTexCoord2f(0.0f,1.0f);
        //glTexCoord2f((float)(i)/(float)sizeX,(float)(j+1.0)/(float)sizeZ);
        glVertex3f(v4.x, v4.y, v4.z);
        
      }
      if(first){
        shadow->createGroundList();
        first=false;
        }
        
  glEnd();
  
  
  // Disable Textures Again, for Performance reasons.
  //glLoadIdentity();
  glDisable(GL_TEXTURE_2D);

  
  //draw track
  glBegin(GL_LINES);
  glColor3f(0.0, 1.0, 1.0);
  for( int i = 0; i < tracklen; i++)
    {
      glVertex3f(pathnodes[i].x,pathnodes[i].y,pathnodes[i].z);
      glVertex3f(pathnodes[(i+1)%tracklen].x,pathnodes[(i+1)%tracklen].y,pathnodes[(i+1)%tracklen].z);
    }
  glEnd();
  


  trackManager->drawGraph(.01);
  trackManager->debug(2);
  delete trackManager;
    
  glEndList();
 shadow->init();  
  
}


/** 
    \brief checks for collisions
    
    This method runs through all WorldEntities known to the world and checks for collisions 
    between them. In case of collisions the collide() method of the corresponding entities 
    is called.
*/
void World::collide ()
{
  /*
  List *a, *b;
  WorldEntity *aobj, *bobj;
   
  a = entities;
  
  while( a != NULL)
    {
      aobj = a->nextElement();
      if( aobj->bCollide && aobj->collisioncluster != NULL)
        {
          b = a->nextElement();
          while( b != NULL )
            {
              bobj = b->nextElement();
              if( bobj->bCollide && bobj->collisioncluster != NULL )
                {
                  unsigned long ahitflg, bhitflg;
                  if( check_collision ( &aobj->place, aobj->collisioncluster, 
                                        &ahitflg, &bobj->place, bobj->collisioncluster, 
                                        &bhitflg) );
                  {
                    aobj->collide (bobj, ahitflg, bhitflg);
                    bobj->collide (aobj, bhitflg, ahitflg);
                  }
                }
              b = b->nextElement();
            }
        }
      a = a->enumerate();
    }
  */
}

/** 
    \brief runs through all entities calling their draw() methods
*/
void World::draw ()
{
  // draw entities
  
  
  WorldEntity* entity;
  entity = this->entities->enumerate();
  while( entity != NULL ) 
    { 
      if( entity->bDraw ) entity->draw();
      entity = this->entities->nextElement();
    } 
  
  //glmis = new GLMenuImageScreen();
  ///glmis->init();

  // draw debug coord system
  //glLoadIdentity();
  
  glCallList (objectList);
 

  //After calling the list, draw the skysphere
 
  glEnable(GL_TEXTURE_2D);
  skysphere->draw();
  
  shadow->draw();
  
  
  
}

/** 
    \brief updates Placements and notifies entities when they left the 
    world
    
    This runs trough all WorldEntities and maps Locations to Placements 
    if they are bound, checks whether they left the level boundaries 
    and calls appropriate functions.
*/
void World::update ()
{
    
  /*
  //List<WorldEntity> *l;
  WorldEntity* entity;
  Location* loc;
  Placement* plc;
  Uint32 t;
  
  //  l = entities->enumerate(); 
  entity = this->entities->enumerate();
  while( entity != NULL ) 
    { 

      
      if( !entity->isFree() )
        {
          loc = entity->getLocation();
          plc = entity->getPlacement();
          t = loc->part;
          
          if( t >= tracklen )
            {
              printf("An entity is out of the game area\n");
              entity->leftWorld ();
            }
          else
            {
              while( track[t].mapCoords( loc, plc) )
                {
                  track[t].postLeave (entity);
                  if( loc->part >= tracklen )
                    {
                      printf("An entity has left the game area\n");
                      entity->leftWorld ();
                      break;
                    }
                  track[loc->part].postEnter (entity);
                }
            }
        }
      else
        {
        }
      
      entity = entities->nextElement();
    }
  */  
}

/** 
    \brief relays the passed time since the last frame to entities and Track parts
    \param deltaT: the time passed since the last frame in milliseconds
*/
void World::timeSlice (Uint32 deltaT)
{
  //List<WorldEntity> *l;
  WorldEntity* entity;
  float seconds = deltaT / 1000.0;
  
  this->nullParent->update (seconds);
  //this->nullParent->processTick (seconds);

  entity = entities->enumerate(); 
  while( entity != NULL) 
    { 
      entity->tick (seconds);
      entity = entities->nextElement();
    }
  
  skysphere->updatePosition(localPlayer->absCoordinate.x,localPlayer->absCoordinate.y,localPlayer->absCoordinate.z);
  shadow->updatePosition(localPlayer->absCoordinate.x,localPlayer->absCoordinate.y,localPlayer->absCoordinate.z);
  //for( int i = 0; i < tracklen; i++) track[i].tick (seconds);
}

/**
   \brief removes level data from memory
*/
void World::unload()
{
  if( pathnodes) delete []pathnodes;
  if( track) delete []pathnodes;
}


void World::setTrackLen(Uint32 len)
{
  this->tracklen = len;
}

int World::getTrackLen()
{
  return this->tracklen;
}



/**
   \brief function to put your own debug stuff into it. it can display informations about
   the current class/procedure
*/
void World::debug()
{
  printf ("World::debug() - starting debug\n");
  PNode* p1 = NullParent::getInstance ();
  PNode* p2 = new PNode (new Vector(2, 2, 2), p1);
  PNode* p3 = new PNode (new Vector(4, 4, 4), p1);
  PNode* p4 = new PNode (new Vector(6, 6, 6), p2);

  p1->debug ();
  p2->debug ();
  p3->debug ();
  p4->debug ();

  p1->shiftCoor (new Vector(-1, -1, -1));

  printf("World::debug() - shift\n");
  p1->debug ();
  p2->debug ();
  p3->debug ();
  p4->debug ();
  
  p1->update (1);

  printf ("World::debug() - update\n");
  p1->debug ();
  p2->debug ();
  p3->debug ();
  p4->debug ();

  p2->shiftCoor (new Vector(-1, -1, -1));
  p1->update (2);

  p1->debug ();
  p2->debug ();
  p3->debug ();
  p4->debug ();

  p2->setAbsCoor (new Vector(1,2,3));


 p1->update (2);

  p1->debug ();
  p2->debug ();
  p3->debug ();
  p4->debug ();

  p1->destroy ();
  
  
  /*
  WorldEntity* entity;
  printf("counting all entities\n");
  printf("World::debug() - enumerate()\n");
  entity = entities->enumerate();  
  while( entity != NULL ) 
    { 
      if( entity->bDraw ) printf("got an entity\n");
      entity = entities->nextElement();
    }
  */
}


/*
  \brief main loop of the world: executing all world relevant function

  in this loop we synchronize (if networked), handle input events, give the heart-beat to
  all other member-entities of the world (tick to player, enemies etc.), checking for
  collisions drawing everything to the screen.
*/
void World::mainLoop()
{
  this->lastFrame = SDL_GetTicks ();
  printf("World::mainLoop() - Entering main loop\n");
  while( !this->bQuitOrxonox && !this->bQuitCurrentGame) /* \todo implement pause */
    {
      // Network
      this->synchronize ();
      // Process input
      this->handleInput ();
      if( this->bQuitCurrentGame || this->bQuitOrxonox)
        {
          printf("World::mainLoop() - leaving loop earlier...\n");
          break;
        }
      // Process time
      this->timeSlice ();
      // Process collision
      this->collision ();
      // Draw
      this->display ();
  
      for( int i = 0; i < 5000000; i++) {}
      /* \todo this is to slow down the program for openGl Software emulator computers, reimplement*/
    }
  printf("World::mainLoop() - Exiting the main loop\n");
}

/**
   \brief synchronize local data with remote data
*/
void World::synchronize ()
{
  // Get remote input
  // Update synchronizables
}

/**
   \brief run all input processing

   the command node is the central input event dispatcher. the node uses the even-queue from
   sdl and has its own event-passing-queue.
*/
void World::handleInput ()
{
  // localinput
  CommandNode* cn = Orxonox::getInstance()->getLocalInput();
  cn->process();
  // remoteinput
}

/**
   \brief advance the timeline

   this calculates the time used to process one frame (with all input handling, drawing, etc)
   the time is mesured in ms and passed to all world-entities and other classes that need
   a heart-beat.
*/
void World::timeSlice ()
{
  Uint32 currentFrame = SDL_GetTicks();
  if(!this->bPause)
    {
      Uint32 dt = currentFrame - this->lastFrame;
      
      if(dt > 0)
        {
          float fps = 1000/dt;
          printf("fps = %f\n", fps);
        }
      else
        {
          /* the frame-rate is limited to 100 frames per second, all other things are for
             nothing.
          */
          printf("fps = 1000 - frame rate is adjusted\n");
          SDL_Delay(10);
          dt = 10;
        }
      this->timeSlice (dt);
      this->update ();
      this->localCamera->timeSlice(dt);
    }
  this->lastFrame = currentFrame;
}


/**
   \brief compute collision detection
*/
void World::collision ()
{
  this->collide ();
}


/**
   \brief render the current frame
   
   clear all buffers and draw the world
*/
void World::display ()
{
  // clear buffer
  glClear( GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
  // set camera
  this->localCamera->apply ();
  // draw world
  this->draw();
  // draw HUD
  /* \todo draw HUD */
  // flip buffers
  SDL_GL_SwapBuffers();
  //SDL_Surface* screen = Orxonox::getInstance()->getScreen ();
  //SDL_Flip (screen);
}

/**
   \brief give back active camera
   
   this passes back the actualy active camera
   \todo ability to define more than one camera or camera-places
*/
Camera* World::getCamera()
{
  return this->localCamera;
}


/**
   \brief add and spawn a new entity to this world
   \param entity to be added
*/
void World::spawn(WorldEntity* entity)
{
  if( this->nullParent != NULL && entity->parent == NULL)
    this->nullParent->addChild (entity);

  this->entities->add (entity);

  entity->postSpawn ();
}


/**
   \brief add and spawn a new entity to this world
   \param entity to be added
   \param location where to add
*/
void World::spawn(WorldEntity* entity, Vector* absCoor, Quaternion* absDir)
{
  entity->setAbsCoor (absCoor);
  entity->setAbsDir (absDir);
  
  if( this->nullParent != NULL && entity->parent == NULL)
    this->nullParent->addChild (entity);

  this->entities->add (entity);

  entity->postSpawn ();
}



/*
  \brief commands that the world must catch
  \returns false if not used by the world
*/
bool World::command(Command* cmd)
{
  return false;
}




void World::swap (unsigned char &a, unsigned char &b)
{
  unsigned char temp;
  temp = a;
  a    = b;
  b    = temp;
}