__author__ = 'Lenovo'
import math
from math import pi
import numpy as np
import matplotlib.pyplot as plt

def makePath(alpha, v0, k, eps, xmax, ymax):
    # print alpha
    alpha = math.radians(alpha)
    # print alpha
    vx = v0 * np.cos(alpha)
    vy = v0 * np.sin(alpha)
    xcur = xmax*0.5
    ycur = ymax*0.5

    while vx**2 + vy**2 > eps:
        plt.bar(0, ymax, xmax, 0, color = 'w')
        #plt.show()
        if alpha <= pi/2:
            if ycur + (xmax - xcur) * np.tan(alpha) > ymax: #top
                t1 = np.linspace(xcur, xcur + (ymax - ycur)/ np.tan(alpha), 2)
                plt.plot(t1, np.tan(alpha)*t1 + ycur - xcur*np.tan(alpha))
                xcur = xcur + abs((ymax - ycur)/ np.tan(alpha))
                ycur = ymax
                alpha = 2*pi - alpha
            else: #right
                t1 = np.linspace(xcur, xmax, 2)
                plt.plot(t1, np.tan(alpha)*t1 + ycur - xcur*np.tan(alpha))
                ycur = ycur + xmax * np.tan(alpha)- xcur*np.tan(alpha)
                xcur = xmax
                alpha = pi - alpha
        elif alpha <= pi:
            if ycur + abs(xcur * np.tan(alpha)) > ymax: #top
                t1 = np.linspace(xcur - abs((ymax - ycur)/ np.tan(alpha)), xcur, 2)
                plt.plot(t1, np.tan(alpha)*t1 + ycur + abs(xcur * np.tan(alpha)))
                xcur = xcur - abs((ymax - ycur)/ np.tan(alpha))
                ycur = ymax
                alpha = 2*pi - alpha
            else: #left
                t1 = np.linspace(0, xcur, 2)
                plt.plot(t1, np.tan(alpha)*t1 + ycur + abs(xcur * np.tan(alpha)))
                ycur = ycur + abs(xcur * np.tan(alpha))
                xcur = 0
                alpha = pi - alpha
        elif alpha <= 3*pi/2:
            if ycur - abs(xcur * np.tan(alpha)) < 0: #bottom
                t1 = np.linspace(xcur - abs(ycur/ np.tan(alpha)), xcur, 2)
                plt.plot(t1, np.tan(alpha)*t1 + ycur - abs(xcur * np.tan(alpha)))
                xcur = xcur - abs(ycur/ np.tan(alpha))
                ycur = 0
                alpha = 2*pi - alpha
            else: #left
                t1 = np.linspace(0, xcur, 2)
                plt.plot(t1, np.tan(alpha)*t1 + ycur - abs(xcur * np.tan(alpha)))
                ycur = ycur - abs(xcur * np.tan(alpha))
                xcur = 0
                alpha = 3*pi - alpha
        else:
            if ycur - abs((xmax - xcur) * np.tan(alpha)) < 0: #bottom
                t1 = np.linspace(xcur, xcur + abs(ycur/ np.tan(alpha)), 2)
                plt.plot(t1, np.tan(alpha)*t1 + ycur + abs(xcur * np.tan(alpha)))
                xcur = xcur + abs(ycur/ np.tan(alpha))
                ycur = 0
                alpha = 2*pi - alpha
            else: #right
                t1 = np.linspace(xcur, xmax, 2)
                plt.plot(t1, np.tan(alpha)*t1 + ycur + abs(xcur * np.tan(alpha)))
                ycur = ycur - abs((xmax - xcur) * np.tan(alpha))
                xcur = xmax
                alpha = 3*pi - alpha
        vx = vx*k
        vy = vy*k
    plt.show()

makePath(300, 20, 0.9, 0.1, 20, 40)