creating an object at another objects position

[deanhystad]

I was having a tough time understanding the lasers. Took the name too literally and expected a line that grows in length and didn't see how your rectangles would ever do something like that. But your lasers are projectiles which is fairly easy. The thing you are missing is the after() method.

import math
import tkinter as tk
import random

window_height = 400
window_width = 720

class Laser:
    instances = []
    colors = ('red', 'yellow', 'blue', 'orange', 'green', 'purple', 'pink', 'brown', 'grey')

    @classmethod
    def update(cls):
        """Move all the lasers.  Remove offscreen lasers"""
        cls.instances = [laser for laser in cls.instances if laser.move()]

    def __init__(self, x, y, dx, dy):
        self.id = canvas.create_line(x, y, x, y, width=3, fill=random.choice(self.colors))
        self.x = x
        self.y = y
        self.dx = dx
        self.dy = dy
        self.length = 0
        self.instances.append(self)

    def move(self):
        """Update laser position.  Return True if visible"""
        self.length = min(30, self.length+1)
        self.x += self.dx
        self.y += self.dy
        x = self.x - self.length * self.dx
        y = self.y - self.length * self.dy
        if 0 <= x <= window_width and 0 <= y <= window_height:
            canvas.coords(self.id, int(x), int(y), int(self.x), int(self.y))
            return True
        canvas.delete(self.id)
        return False

def update_lasers():
    """Periodically update the lasers"""
    Laser.update()
    root.after(10, update_lasers)

def fire(*args):
    """Fire a rainbow starburst of lasers"""
    step = random.randint(1, 60)
    for angle in range(step//2, 360, step):
        angle = math.radians(angle)
        Laser(360, 200, math.sin(angle), math.cos(angle))

root = tk.Tk()
canvas = tk.Canvas(root, width=window_width, height=window_height)
canvas.pack()
root.bind("<space>", fire)
update_lasers()
root.mainloop()