///////////////////////////////////////////////////////////////////////////////
// Soubor studentskych funkci
///////////////////////////////////////////////////////////////////////////////
 
///////////////////////////////////////////////////////////////////////////////
// include
 
#include "main.h"
 
#include <assert.h>
#include <stdlib.h>
#include <iostream>
 
///////////////////////////////////////////////////////////////////////////////
// name spaces
 
using namespace std;
 
//Mocnina
double Power(double a, int b)
{
  double result = 1.0;
  for (int i = 0; i < b; ++i)
  {
  	result *= a;
  }
  return result;
}
 
 
/////////////////// ZDE DOPLNTE IMPLEMENTACI ZA DOMACI UKOL ////////////////////
double N(int i, int k, double t, const K_NOT & U) {
	double b;
	if (k == 0) {
		if ((t >= U[i]) && (t < U[i + 1])) {
			return 1.0;
		}
		return 0.0;
	}
	if (!EQUAL_ZERO(U[i + k] - U[i])) {
		b = (t - U[i]) / (U[i + k] - U[i]) * N(i, k - 1, t, U);
	}
	if (!EQUAL_ZERO(U[i + k + 1] - U[i + 1])) {
		b += (U[i + k + 1] - t) / (U[i + k + 1] - U[i + 1]) * N(i + 1, k - 1, t, U);
	}
	return b;
}
 
 
void BSpline(int quality, const T_PointVector & points, T_PointVector & line_points , const BSplineDescription & bsplinedsc) {
	double t;
	int k;
	double step = 1.0 / quality;
	for (k = 0, t = 0.0; k <= quality; k++, t += step) {
		if (t >= 1.0) {
			t = 0.9;
		}
		int i;
		double p;
		double x;
		double y;
		for (i = 0, x = y = p = 0.0; i <= bsplinedsc.n; i++) {
			double b = points[i].weight * N(i, bsplinedsc.k, t, bsplinedsc.U);
			x += points[i].x * b;
			y += points[i].y * b;
			p += b;
		}
		if (EQUAL_ZERO(p)) {
			x = y = 0.0;
		} else {
			x /= p;
			y /= p;
		}
		line_points.push_back(S_Point(x, y));
	}
 
}
////////////////////////////////////////////////////////////////////////////////