Python Turtle object not moving

Question

I am making a simple Object-oriented projectile simulation program in python. I am just using the Turtle and Math modules. The problem is when I try to simply move my projectile (as a test before integrating some equations) it does not move.

import turtle
from turtle import Turtle
import math

window = turtle.Screen()
window.title("Projectile")
window.bgcolor("black")
window.setup(width=800, height=800)
window.tracer(0)

def drawLine():
    line = turtle.Turtle()
    line.penup()
    line.pencolor("white")
    line.pensize(10)
    line.goto(-400, -300)
    line.pendown()
    line.forward(800)
    line.penup()
    line.ht()

class Projectile:
    def __init__(self, x, y, color, shape, a, b):
        self.turtle = turtle.Turtle()
        self.turtle.goto(x, y)
        self.turtle.color(color)
        self.turtle.shape(shape)
        self.turtle.shapesize(a, b)

    def launch(self, x, y):
        self.turtle.penup()
        self.turtle.setx(self.turtle.xcor() + x)
        self.turtle.sety(self.turtle.ycor() + y)

running = True
while running:
    window.update()

    drawLine()
    projectileOne = Projectile(-290, -290, "red", "circle", 1, 1)
    projectileOne.launch(25, 25)

This is supposed to move my turtle, isn't it?

self.turtle.setx(self.turtle.xcor() + x)
self.turtle.sety(self.turtle.ycor() + y)

I don't understand what's happening. Why isn't the projectile moving? It just moves (25, 25) and stops.

The errors I get after the code runs:

 Traceback (most recent call last):
  File "C:\Users\HP\Desktop\Python projects\test\test.py", line 39, in <module>
    drawLine()
  File "C:\Users\HP\Desktop\Python projects\test\test.py", line 12, in drawLine
    line = turtle.Turtle()
  File "C:\Users\HP\AppData\Local\Programs\Python\Python38-32\lib\turtle.py", line 3813, in __init__
    RawTurtle.__init__(self, Turtle._screen,
  File "C:\Users\HP\AppData\Local\Programs\Python\Python38-32\lib\turtle.py", line 2557, in __init__
    self._update()
  File "C:\Users\HP\AppData\Local\Programs\Python\Python38-32\lib\turtle.py", line 2660, in _update
    self._update_data()
  File "C:\Users\HP\AppData\Local\Programs\Python\Python38-32\lib\turtle.py", line 2646, in _update_data
    self.screen._incrementudc()
  File "C:\Users\HP\AppData\Local\Programs\Python\Python38-32\lib\turtle.py", line 1292, in _incrementudc
    raise Terminator
turtle.Terminator
[Finished in 7.4s]

And if I completely remove drawLine() from the code I get:

Traceback (most recent call last):
File "C:\Users\HP\Desktop\Python projects\test\test.py", line 40, in <module>
        projectileOne = Projectile(-290, -290, "red", "circle", 1, 1)
      File "C:\Users\HP\Desktop\Python projects\test\test.py", line 24, in __init__
        self.turtle = turtle.Turtle()
      File "C:\Users\HP\AppData\Local\Programs\Python\Python38-32\lib\turtle.py", line 3813, in __init__
        RawTurtle.__init__(self, Turtle._screen,
      File "C:\Users\HP\AppData\Local\Programs\Python\Python38-32\lib\turtle.py", line 2557, in __init__
        self._update()
      File "C:\Users\HP\AppData\Local\Programs\Python\Python38-32\lib\turtle.py", line 2660, in _update
        self._update_data()
      File "C:\Users\HP\AppData\Local\Programs\Python\Python38-32\lib\turtle.py", line 2646, in _update_data
        self.screen._incrementudc()
      File "C:\Users\HP\AppData\Local\Programs\Python\Python38-32\lib\turtle.py", line 1292, in _incrementudc
        raise Terminator
    turtle.Terminator
    [Finished in 5.2s]

You call the only drawing function,`drawLine()`, over and over again. It keeps drawing the same line. The `launch` method never lowers the pen. — DYZ, May 25 '20 at 04:50
I completely removed `drawLine()` from the main loop, but it still does not work. I updated my question with the errors I get after I close the program. Is there is a problem with `something = turtle.Turtle()` ? — Mush-A, May 25 '20 at 07:54

score 2 · Accepted Answer · answered May 25 '20 at 16:20

The errors you get after you close the program are not directly related to your drawing issue. They're caused by this logic:

running = True
while running:

An infinite loop like this has no place in an event-driven environment like turtle, it potentially blocks events. (Like the "window is closing" event.) Instead, use a timer event to keep things running.

Below is a rewrite of your code that uses timer events to launch a couple of (gravity ignorant) projectiles that will keep flying until they reach the top of the window. Hopefully this will give you a framework upon which to build your simulation:

from turtle import Screen, Turtle

class Projectile(Turtle):
    def __init__(self, position, color, shape, width, length):
        super().__init__(shape=shape)

        self.color('white', color)
        self.shapesize(width, length)
        self.penup()
        self.setposition(position)
        self.pendown()
        self.pensize(4)

        self.flying = False
        screen.update()

    def launch(self, angle):
        self.setheading(angle)
        self.flying = True
        self.fly()

    def fly(self):
        if self.flying:
            self.forward(3)

            if self.ycor() > screen.window_height()/2:
                self.flying = False

            screen.ontimer(self.fly, 50)

        screen.update()

screen = Screen()
screen.setup(width=800, height=800)
screen.title("Projectile")
screen.bgcolor('black')
screen.tracer(0)

projectileOne = Projectile((-290, -290), 'red', 'triangle', 1, 2)
projectileTwo = Projectile((290, -290), 'green', 'circle', 1, 1)

projectileOne.launch(75)
projectileTwo.launch(130)

screen.mainloop()

Thank you this is exactly what I wanted! – Mush-A May 27 '20 at 05:16 — Mush-A, May 27 '20 at 05:16

Python Turtle object not moving

1 Answers1