我的定时运动Zelle graphics.py程序错误

Question

I tried to make a program into which you enter a speed (pixels per second), so a point in the window will move at that exact speed on the x axis. I enter the speed, but the point isn't moving and IDLE does not complain with an error.

from graphics import *
import time
win=GraphWin("Time", 600, 600)
point=Point(50, 100)
point.setFill("green")
point.draw(win)
speed=Entry(Point(100,50), 15)
speed.setText("Pixels per second")
speed.draw(win)
win.getMouse()
speed1=speed.getText()

speed1=eval(speed1)
t=0.0
time=time.clock()

if time==t+1:
   t+=1
   point.move(speed1, 0)

Can someone tell me what I did wrong here? I'm using Python 3.4

Answer 1

The number of seconds returned by time.clock() is a floating-point number. The likelihood that it will happen to be equal to t+1 is low enough that your point very rarely moves. Instead of using == , use >= :

if time >= t + 1:
    t += 1
    point.move(speed1, 0)

Answer 2

It doesn't move because this is not a loop:

if time==t+1:
   t+=1
   point.move(speed1, 0)

time isn't == , nor >= , to t+1 so it goes past and the program is finished. What you need is:

import time
from graphics import *

WINDOW_WIDTH, WINDOW_HEIGHT = 600, 600

win = GraphWin("Time", WINDOW_WIDTH, WINDOW_HEIGHT)

circle = Circle(Point(50, 200), 10)
circle.setFill("green")
circle.draw(win)

speed = Entry(Point(100, 50), 15)
speed.setText("Pixels per second")
speed.draw(win)

win.getMouse()
velocity = float(speed.getText())

t = time.clock()

while circle.getCenter().x < WINDOW_WIDTH:
    if time.clock() >= t + 1:
        t += 1
        circle.move(velocity, 0)

I used a larger object as it was just too hard to see the 1 pixel bright green point moving.