# cball3.py
#   Simulation of the flight of a cannon ball (or other projectile)
#   Illustrates use of a class/object to organize data

from math import pi, sin, cos

class Projectile:

    def __init__(self, angle, velocity, height):
        self.xpos = 0.0
        self.ypos = height
        theta = pi * angle / 180.0
        self.xvel = velocity * cos(theta)
        self.yvel = velocity * sin(theta)

    def update(self, time):
        self.xpos = self.xpos + time * self.xvel
        yvel1 = self.yvel - 9.8 * time
        self.ypos = self.ypos + time * (self.yvel + yvel1) / 2.0
        self.yvel = yvel1

    def getY(self):
        return self.ypos

    def getX(self):
        return self.xpos

def getInputs():
    a = input("Enter the launch angle (in degrees): ")
    v = input("Enter the initial velocity (in meters/sec): ")
    h = input("Enter the initial height (in meters): ")
    t = input("Enter the time interval between position calculations: ")
    return a,v,h,t

def main():
    angle, vel, h0, time = getInputs()
    cball = Projectile(angle, vel, h0)
    while cball.getY() >= 0:
        cball.update(time)        
    print "\nDistance traveled: %0.1f meters." % (cball.getX())

main()