# -*- coding: utf-8 -*-

# import importlib
# importlib.import_module("./vector")
from vector import Vector

class Bezier:
    
    def __init__(self,pts):
        if len(pts)==4:
            self.pts = [p.copy() for p in pts]
        if len(pts)==3:
            self.pts = [pts[0].copy(), 1/3*pts[0]+2/3*pts[1], 1/3*pts[2]*2/3*pts[1], pts[2].copy()]
        if len(pts)==2:
            self.pts = [pts[0].copy(), 2/3*pts[0]+1/3*pts[1], 1/3*pts[0]+2/3*pts[1], pts[1].copy()]
        
    # Punkt für Parameter t (in [0,1])        
    def x(self,t):
        return (1.0-t)**3*self.pts[0]+\
               3*(1.0-t)**2*t*self.pts[1]+\
               3*(1.0-t)*t**2*self.pts[2]+\
               t**3*self.pts[3]

    # Geschwindigkeit (dx/dt) in t-Parametrierung
    def v(self,t):
        return -3*(1.0-t)**2*self.pts[0]+\
               3*(1.0-4*t+3*t**2)*self.pts[1]+\
               3*(2*t-3*t**2)*self.pts[2]+\
               3*t**2*self.pts[3]

   
    # Zeichnet den Spline
    # Achtung: Funktioniert nur, wenn diese Datei ausgeführt wird...
    def draw(self, steps=1000):
        move(self.pts[0][0], self.pts[0][1]);
        for i in range(1,steps+1):
            p = self.x(1.0*i/steps)
            lineTo((p[0],p[1]))
                        

if __name__== "__main__":
    from gpanel import *
    makeGPanel(Size(600,600))
    window(0, 599, 0, 599)
    b = Bezier([Vector([100,500,0]), Vector([200,0,0]), Vector([300,300,0]), Vector([500,300,0])])
    b.draw()