/* 
   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: Patrick Boenzli

   ADD: Patrick Boenzli           B-Spline 


   TODO: 
     local-Time implementation
     NURBS
     
*/

#include "curve.h"

#include <math.h>
#include <stdio.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);
  this->rebuild();
  return;
}


/**
   \brief Creates a new BezierCurve
*/
BezierCurve::BezierCurve (void)
{
  this->derivation = 0;
  dirCurve = new BezierCurve(1);
  this->init();
}

/**
   \brief Creates a new BezierCurve-Derivation-Curve
*/
BezierCurve::BezierCurve (int derivation)
{
  this->derivation = derivation;
  dirCurve=NULL;
  this->init();
}

/**
   \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;
    }
  if (dirCurve)
    delete dirCurve;
}

/**
   \brief Initializes a BezierCurve
*/
void BezierCurve::init(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 Rebuilds a Curve
*/
void BezierCurve::rebuild(void)
{
  PathNode* tmpNode = firstNode;

  // rebuilding the Curve itself
  int k=0;
  int binCoef = 1;
  while(tmpNode)
    {
      if (k+1 < nodeCount-k)
	binCoef *=(nodeCount-k)/(k+1);
      else
	binCoef /= (k+1)/(nodeCount-k);
      ++k;
      tmpNode->factor = binCoef;
      tmpNode = tmpNode->next;
    }

  // rebuilding the Derivation curve
  if(this->derivation == 0)
    {
      tmpNode = firstNode;
      delete dirCurve;
      dirCurve = new BezierCurve(1);
      while(tmpNode->next)
	{
	  Vector tmpVector = (tmpNode->next->position)- (tmpNode->position);
	  tmpVector.x*=(float)nodeCount;
	  tmpVector.y*=(float)nodeCount;
	  tmpVector.z*=(float)nodeCount;
	  tmpVector.normalize();
	  this->dirCurve->addNode(tmpVector);
	  tmpNode = tmpNode->next;
	}
    }
}

/**
   \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);
  float factor = 1.0*pow(1.0-t,nodeCount);
  while(tmpNode)
    {
      factor *= t/(1.0-t); // same as pow but much faster.
      ret.x += tmpNode->factor * factor * tmpNode->position.x;
      ret.y += tmpNode->factor * factor * tmpNode->position.y;
      ret.z += tmpNode->factor * 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)
{
  return dirCurve->calcPos(t);
}

/**
   \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(void) const
{
  return curvePoint;
}