using UnityEngine;
using System.Collections;

public class DrawBezier : MonoBehaviour    
{
    //Объекты по которым будем римовать кривую
    public GameObject point0;
    public GameObject point1;
    public GameObject point2;
    public GameObject point3;
       
    private Vector3 currentBezierPoint;
    private float currentStep = 0F;
       
    //Массив линий для прорисовки кривой
    private ArrayList lines = new ArrayList();
       
    // Use this for initialization
    void Start ()    
    {
     currentBezierPoint = CalculateBezierPoint(currentStep, point0.transform.position, point1.transform.position , point2.transform.position , point3.transform.position);    
     lines.Add(point0.transform.position);
    }
       
    // Update is called once per frame
   oid Update ()      
  {  
    
   if (point0isBigger)
   {
    if ((currentBezierPoint.x > point3.transform.position.x || currentBezierPoint.y > point3.transform.position.y || currentBezierPoint.z > point3.transform.position.z))
    {
     currentStep += 0.01F;
     currentBezierPoint = CalculateBezierPoint(currentStep, point0.transform.position, point1.transform.position , point2.transform.position , point3.transform.position);
     lines.Add(currentBezierPoint);
    }
   }
   else
   {
    if ((currentBezierPoint.x < point3.transform.position.x || currentBezierPoint.y < point3.transform.position.y || currentBezierPoint.z < point3.transform.position.z))
    {
     currentStep += 0.01F;
     currentBezierPoint = CalculateBezierPoint(currentStep, point0.transform.position, point1.transform.position , point2.transform.position , point3.transform.position);
     lines.Add(currentBezierPoint);
    }
   }
     
   
     
    
  }
       
    void OnRenderObject()    
    {    
        
     Vector3 currentPoint = new Vector3(0,0,0);
     bool isFirstStep = true;
        
     //Рисуем кривые из списка кривых
     foreach (Vector3 line in lines)
     {
      if (isFirstStep)
      {
       currentPoint = line;
       isFirstStep = false;
      }
      else
      {
       GL.Begin(GL.LINES);
             GL.Color(Color.black);
             GL.Vertex(currentPoint);
             GL.Vertex(line);
             GL.End();
       currentPoint = line;
      }
     }
        
    }
       
       

       
    // Формула кубической кривой безье B[x,y,z] = (1-t)^3*p0 + 3t(1-t)^2 *p1 +3t^2(1-t)*p2 + t^3*p3
    // Введем функцию для расчета точки
    private Vector3 CalculateBezierPoint(float t, Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3)
    {
     //Для удобства разобьём по блокам
        
     //блок 0 (1-t)^3*p0
     Vector3 step0 = Mathf.Pow(1-t, 3)*p0;    
        
     //блок 1 3t(1-t)^2 *p1
     Vector3 step1 = Mathf.Pow(1-t, 2) *3*t*p1;
        
     //блок 2 3t^2(1-t)*p2
     Vector3 step2 = 3*Mathf.Pow(t,2)*(1-t)*p2;
        
     //блок 3 t^3*p3
     Vector3 step3 = Mathf.Pow(t,3)*p3;
         
        
     return step0 + step1 + step2 + step3;
       
        
    }
}