I am writing a program for an exercise that simulates a projectile launch while tracking down every x and y position per second.
While the program technically works, and it does track down every x and y position, the text that tracks down the x and y position flickers for each step.
I understand the problem is that I am using the .clear() function (which, as its name implies, clears the text generated by the turtle). However, I believe that the program only functions properly with it.
Here is my code:
"""Program to track specific location of turtle (for every step)"""
from turtle import *
from math import *
def cball_graphics():
leonardo = Turtle()
leonardo.color("dark blue")
leonardo.shape("turtle")
leonardo.speed(1)
return leonardo
def show_position():
pos = Turtle()
pos.color("white")
pos.goto(30, -50)
pos.color("red")
return pos
class cannon_ball:
def __init__(self, angle, vel, height, time):
self.x_pos = 0
self.y_pos = height
theta = pi * angle / 180
self.x_vel = vel * cos(theta)
self.y_vel = vel * sin(theta)
self.time = time
def update_time(self):
self.x_pos += self.time * self.x_vel
y_vel1 = self.y_vel - 9.8 * self.time
self.y_pos += self.time * (self.y_vel + y_vel1) / 2
self.y_vel = y_vel1
def get_x(self):
return self.x_pos
def get_y(self):
return self.y_pos
def variables():
angle = 55
vel = 10
height = 100
time = .01
return cannon_ball(angle, vel, height, time)
def main():
leonardo = cball_graphics()
"""pos is a variable that writes the position on the screen using x and y pos"""
pos = show_position()
pos.hideturtle()
projectile = variables()
while projectile.y_pos >= 0:
pos.write(f"{'%0.0f' % projectile.x_pos}, {'%0.0f' % projectile.y_pos}")
projectile.update_time()
leonardo.goto(projectile.x_pos, projectile.y_pos)
pos.clear()
main()
I believe that the tracer() and update() methods of the turtle screen will solve your problem. They allow you to write to the backing store and then copy it to the screen once it’s the way you want. Particularly useful for eliminating flicker:
from turtle import Screen, Turtle
from math import pi, sin, cos
FONT = ('Arial', 18, 'normal')
def cball_graphics():
leonardo = Turtle()
leonardo.color('dark blue')
leonardo.shape('turtle')
return leonardo
def show_position():
pos = Turtle()
pos.hideturtle()
pos.goto(30, -50)
pos.color('red')
return pos
class cannon_ball:
def __init__(self, angle, velocity, height, time):
self.x_pos = 0
self.y_pos = height
theta = pi * angle / 180
self.x_vel = velocity * cos(theta)
self.y_vel = velocity * sin(theta)
self.time = time
def update_time(self):
self.x_pos += self.time * self.x_vel
y_vel1 = self.y_vel - 9.8 * self.time
self.y_pos += self.time * (self.y_vel + y_vel1) / 2
self.y_vel = y_vel1
def freefall():
if projectile.y_pos >= 0:
pos.clear()
pos.write("({:0.0f}, {:0.0f})".format(projectile.x_pos, projectile.y_pos), font=FONT)
projectile.update_time()
leonardo.goto(projectile.x_pos, projectile.y_pos)
screen.update()
screen.ontimer(freefall)
variables = {
'angle': 55,
'velocity': 10,
'height': 100,
'time': 0.01,
}
screen = Screen()
screen.tracer(False)
leonardo = cball_graphics()
# pos is a turtle that writes the position on the screen using x and y pos
pos = show_position()
projectile = cannon_ball(**variables)
freefall()
screen.mainloop()
I also made several style changes to the code while I was at it…