/* 
   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: Benjamin Grauer
   co-programmer: ...

   TODO: 
     local-Time implementation
     closed Bezier Curve
     NURBS
     
*/

#include "curve.h"



/**
   \brief adds a new Node to the bezier Curve
   \param newNode a Vector to the position of the new node
*/
void Curve::addNode(const Vector& newNode)
{
  if (nodeCount != 0 )
    {
      currentNode = currentNode->next = new PathNode;
    }
  currentNode->position = newNode;
  currentNode->next = 0; // not sure if this really points to NULL!!
  currentNode->number = (++nodeCount);
  return;
}


/**
   \brief Creates a new BezierCurve
*/
BezierCurve::BezierCurve (void)
{
  nodeCount = 0;
  firstNode = new PathNode;
  currentNode = firstNode;

  firstNode->position = Vector (.0, .0, .0);
  firstNode->number = 0;
  firstNode->next = 0; // not sure if this really points to NULL!!

  return;
}

/**
   \brief Deletes a BezierCurve.

   It does this by freeing all the space taken over from the nodes
*/
BezierCurve::~BezierCurve (void)
{
  PathNode* tmpNode;
  currentNode = firstNode;
  while (tmpNode != 0)
    {
      tmpNode = currentNode;
      currentNode = currentNode->next;
      delete tmpNode;
    }
}

/**
   \brief calculates the Position on the curve
   \param t The position on the Curve (0<=t<=1)
   \return the Position on the Path
*/
Vector BezierCurve::calcPos(float t) 
{
  if (nodeCount <=4)
    {
      //      if (verbose >= 1)
      //      printf ("Please define at least 4 nodes, until now you have only defined %i.\n", nodeCount);
      return Vector(0,0,0);
    }
  PathNode* tmpNode = firstNode;
    
  Vector ret = Vector(0.0,0.0,0.0);
  double factor;
  int k=0;
  while(tmpNode!=0)
    {
      k++;
      factor = ncr (nodeCount, k);
      
      for (int j=0; j<nodeCount-k; j++)
	factor*=(1-t);
      for (int j=0; j<k; j++)
	factor*=t;
      ret.x += factor * tmpNode->position.x;
      ret.y += factor * tmpNode->position.y;
      ret.z += factor * tmpNode->position.z;
      
      tmpNode = tmpNode->next;

    }
  return ret;
}

/**
   \brief Calulates the direction of the Curve at time t.
   \param The time at which to evaluate the curve.
   \returns The vvaluated Vector.
*/
Vector BezierCurve::calcDir (float t)
{
  PathNode* tmpNode = firstNode;
  BezierCurve* tmpCurve = new BezierCurve();
  Vector ret;
  Vector tmpVector;

  while (tmpNode->next != 0)
    {
      tmpVector = (tmpNode->next->position)- (tmpNode->position);
      tmpVector.x*=(float)nodeCount;
      tmpVector.y*=(float)nodeCount;
      tmpVector.z*=(float)nodeCount;

      tmpCurve->addNode(tmpVector);
      tmpNode = tmpNode->next;
    }
  ret = tmpCurve->calcPos(t);
  ret.normalize();

  return ret;
}

/**
   \brief Calculates the Quaternion needed for our rotations
   \param t The time at which to evaluate the cuve.
   \returns The evaluated Quaternion.
*/
Quaternion BezierCurve::calcQuat (float t)
{
  return Quaternion (calcDir(t), Vector(0,0,1));
}


/**
  \brief returns the Position of the point calculated on the Curve
  \return a Vector to the calculated position
*/
Vector BezierCurve::getPos() const
{
  return curvePoint;
}

/**
   \brief ncr-calculator, did not find an other method
   \todo a c++ variante to do this
*/
int ncr(int n, int i)
{
  int ret = 1;
  for (int k=1; k<=n; k++)
    ret*=k;
  for (int k=1; k<=i; k++)
    ret/=k;
  for (int k=1; k<=n-i; k++)
    ret/=k;

  return ret;
}