python turtle creating flickering images when using tracer(0,0) - python

I am trying to make a program that will repeatedly draw two lines. my code is
import turtle
screen = turtle.Screen()
t = turtle.Turtle()
t.hideturtle()
t.speed(0)
screen.tracer(0,0)
while True:
screen.clear()
t.penup()
t.goto(1,12)
t.pendown()
t.goto(4,67)
t.penup()
t.goto(50, 3)
t.pendown()
t.goto(4, 73)
screen.update()
I expect this to show two lines in turtle which do not flicker. however it is drawing one line and that line is flickering. the lines do need to be redrawn every frame so i can do some other stuff with the lines. Why is this happening?

Short answer: don't do screen.clear(), instead do t.clear().
When you clear the screen, you reset a number of its properties to the default values, including the tracer() setting. You simply want to clear whatever the turtle drew in the last iteration so clear the turtle instead.
In the long term, you don't want while True: in an event-driven environment like turtle. I would write this code more like:
from turtle import Screen, Turtle
def one_step():
turtle.clear()
turtle.penup()
turtle.goto(1, 12)
turtle.pendown()
turtle.goto(4, 67)
turtle.penup()
turtle.goto(50, 3)
turtle.pendown()
turtle.goto(4, 73)
screen.update()
screen.ontimer(one_step, 50)
screen = Screen()
screen.tracer(False)
turtle = Turtle()
turtle.hideturtle()
one_step()
screen.mainloop()

Related

Why won't my square move right? I'm trying all different methods to move it in turtle module it works for up and down but not left and right?

# Game creation
import turtle
wn = turtle.Screen()
wn.title("Pong")
wn.bgcolor("Black")
wn.setup(width=800, height=800)
wn.tracer(0)
# paddle a
paddle_a = turtle.Turtle()
paddle_a.speed(0)
paddle_a.shape("square")
paddle_a.color("white")
paddle_a.penup()
paddle_a.goto(0, 0)
# Functions
def paddle_a_right():
turtle.forward(100)
wn.onkeypress(paddle_a_right, 'd')
while True:
wn.update()
Want the square to move to the right or left using 'a' or 'd' I don't know very much about turtle, I just want to program a simple game.
There are three major issues with your code. First, you need to call wn.listen() to allow the window to receive keyboard input. Second, you do turtle.forward(100) when you mean paddle_a.forward(100). Finally, since you did tracer(0), you now need to call wn.update() anytime a change is made that you want your user to see.
Here's a simplified example:
from turtle import Screen, Turtle
def paddle_right():
paddle.forward(10)
screen.update()
screen = Screen()
screen.title("Pong")
screen.bgcolor("Black")
screen.setup(width=800, height=800)
screen.tracer(0)
paddle = Turtle()
paddle.shape("square")
paddle.color("white")
paddle.penup()
screen.onkeypress(paddle_right, 'd')
screen.listen()
screen.update()
screen.mainloop()

Turtle Text Flashing

When I attempt to put text over a turtle in the python turtle module, it flashes. Any solutions?
import turtle
s = turtle.Screen()
s.setup(width=500,height=600)
c = turtle.Turtle()
c.shapesize(stretch_len=5,stretch_wid=5)
c.goto(0,0)
c.shape("square")
pen = turtle.Turtle()
pen.hideturtle()
pen.goto(0,0)
pen.color("red")
while True:
pen.write("hello!")
s.update()
Although I don't see the flashing on my screen, my guess is your problem is related to this bad idiom:
while True:
# ...
s.update()
We need neither the while True: (which has no place in an event-driven environment like turtle) nor the call to update() (which is not needed given no previous call to tracer()). Let's rewrite this as turtle code:
from turtle import Screen, Turtle
screen = Screen()
screen.setup(width=500, height=600)
turtle = Turtle()
turtle.hideturtle()
turtle.shapesize(5)
turtle.shape('square')
turtle.stamp() # stamp a square so we can reuse turtle
pen = Turtle()
pen.hideturtle()
pen.color("red")
pen.write("Hello!", align='center', font=('Arial', 16, 'normal'))
screen.exitonclick()
Does that solve your problem?

How can I control the outliner's length in Python turtle?

I am making an analog clock with python, using turtle module.
I could configue a window size and a circle, But i can't finish outliner of a circle.
I didn't give any integer to get the complete ouliner. But it doesn't surround a circle entire.
Please, tell me if there is a something missing.
window = turtle.Screen()
window.setup(1000, 800)
window.bgcolor("black")
window.title("Analog Clock")
window.tracer(0)
t = turtle.Turtle()
t.color("#FFD700")
t.penup()
t.speed(0)
t.pensize(25)
t.hideturtle()
t.goto(0, -290)
t.pendown()
t.fillcolor("white")
t.begin_fill()
t.circle(300, 360)
t.end_fill()
thank you
The problem is your use of tracer() without any call to update(). You can either remove the window.tracer(0) line, or add a window.update() line after your t.end_fill() line.
I usually recommend avoiding tracer() and update() until you have your code basically working, just to avoid bugs like this.
from turtle import Screen, Turtle
screen = Screen()
screen.setup(1000, 800)
screen.bgcolor('black')
screen.title("Analog Clock")
screen.tracer(0)
turtle = Turtle()
turtle.hideturtle()
turtle.speed('fastest') # no-op if `tracer(0)`
turtle.color('#FFD700')
turtle.pensize(25)
turtle.penup()
turtle.sety(-290)
turtle.pendown()
turtle.fillcolor('white')
turtle.begin_fill()
turtle.circle(300)
turtle.end_fill()
screen.update()
screen.mainloop()
Here is the solution to your problem with your posted code working properly :)
window = turtle.Screen()
window.setup(1000, 800)
window.bgcolor("black")
window.title("Analog Clock")
t = turtle.Turtle()
t.color("#FFD700")
t.penup()
t.speed(0)
t.pensize(25)
t.hideturtle()
t.goto(0, -290)
t.pendown()
t.fillcolor("white")
t.begin_fill()
t.circle(300, 360)
t.end_fill()
window.update()

How to draw square in Turtle module without filling color?

I am trying to draw a square in turtle without any thing filled in it. I would manually draw it with a loop, but I am trying to write a program where if the square is touched, something would happen. If I drew it with a loop, even if I touch the border, it would not work, because the actual turtle isn't there.
We can do this by dedicating one turtle as the button. We need to change its shape, size and fill color and assign it a button event handler:
from turtle import Screen, Turtle
def thanks(x, y):
marker.write("Thank you!", align='center', font=('Arial', 24, 'bold'))
marker = Turtle()
marker.hideturtle()
marker.penup()
marker.sety(-200)
button = Turtle()
button.shape('square')
button.fillcolor('white')
button.shapesize(3)
button.onclick(thanks)
screen = Screen()
screen.mainloop()
Click on the square in the middle of the screen and it will thank you for doing so.
I am trying to draw a square in turtle without any thing filled in it.
The above solution does use a filled turtle, it just happens to be white fill. We can't draw within the square that is this button. If that's the need, then we can draw the square with a loop, but move our onclick() from the turtle to the screen. We'll need to make the onclick() itself determine if it's in the right place:
from turtle import Screen, Turtle
BUTTON_POSITION = (100, 100)
BUTTON_SIZE = 60
def thanks(x, y):
bx, by = BUTTON_POSITION
if bx < x < bx + BUTTON_SIZE and by < y < by + BUTTON_SIZE:
turtle.write("Thank you!", align='center', font=('Arial', 24, 'bold'))
turtle = Turtle()
turtle.hideturtle()
# draw the button
turtle.penup()
turtle.goto(BUTTON_POSITION)
turtle.pendown()
for _ in range(4):
turtle.forward(BUTTON_SIZE)
turtle.left(90)
# decorate our button a bit
turtle.penup()
turtle.forward(BUTTON_SIZE/2)
turtle.left(90)
turtle.forward(BUTTON_SIZE/2)
turtle.dot()
# position turtle for writing later
turtle.goto(0, -200)
screen = Screen()
screen.onclick(thanks)
screen.mainloop()

Draw then erase square

I'm trying to draw a square using python graphics then erase it after 3 seconds. I have the code below:
import threading as th
import turtle
import random
thread_count = 0
def draw_square():
turtle.goto(random.randint(-200,200), random.randint(-200,200))
for i in range(4):
turtle.forward(100)
turtle.left(90)
def erase_square(x,y):
turtle.pencolor('white')
turtle.fillcolor('white')
turtle.goto(x,y)
turtle.begin_fill()
for i in range(4):
turtle.forward(target_size)
turtle.left(90)
turtle.end_fill()
def square_timer():
global thread_count
if thread_count <= 10:
print("Thread count", thread_count)
draw_square()
T = th.Timer(3, square_timer)
T.start()
The square_update() function will draw 10 squares then stop. I'm trying to make it draw one square then clear it using the erase_square() by painting white over it, then another and repeat the process and stop when it reaches 10. I can't figure how to make the erase function go to the random location of the drawn square and 'erase' it. How can I make it draw and erase the square?
The most straightforward way to clear a drawing is with the clear() method rather than trying to draw white over the image:
from turtle import Screen, Turtle
from random import randint
def draw_square():
turtle.goto(randint(-200, 200), randint(-200, 200))
turtle.pendown()
for _ in range(4):
turtle.forward(100)
turtle.left(90)
turtle.penup()
def erase_square():
turtle.clear()
screen.ontimer(square_update) # no time, ASAP
def square_update():
draw_square()
screen.ontimer(erase_square, 3000) # 3 seconds in milliseconds
screen = Screen()
turtle = Turtle()
turtle.hideturtle()
turtle.speed('fastest')
turtle.penup()
square_update()
screen.exitonclick()
You can use the undo() method as #JonathanDrukker suggests, but you have to undo each step. Even for a simple shape like a square, this takes a little thought, but with a complex shape, this is difficult. The number of operations added to the undo buffer don't always match the calls that you make to turtle. But we can get that count from turtle itself, as long as we don't do any other turtle actions between drawing and erasing:
def draw_square():
turtle.goto(randint(-200, 200), randint(-200, 200))
count = turtle.undobufferentries()
turtle.pendown()
for _ in range(4):
turtle.forward(100)
turtle.left(90)
turtle.penup()
return turtle.undobufferentries() - count
def erase_square(undo_count):
for _ in range(undo_count):
turtle.undo()
screen.ontimer(square_update)
def square_update():
undo_count = draw_square()
screen.ontimer(lambda: erase_square(undo_count), 3000)
But what I'd do is make the turtle itself the square and then just move it rather than erase and (re)draw the square:
from turtle import Screen, Turtle
from random import randint
CURSOR_SIZE = 20
def draw_square():
turtle.goto(randint(-200, 200), randint(-200, 200))
def square_update():
turtle.hideturtle()
draw_square()
turtle.showturtle()
screen.ontimer(square_update, 3000)
screen = Screen()
turtle = Turtle()
turtle.hideturtle()
turtle.shape('square')
turtle.shapesize(100 / CURSOR_SIZE)
turtle.fillcolor('white')
turtle.penup()
square_update()
screen.exitonclick()

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