Procedurally-animated worm in Python

procedural-worm.py

# A simple program which shows a procedurally-animated worm that can be moved around by clicking on the screen.
# References: https://mcsp.wartburg.edu/zelle/python/graphics/graphics/graphref.html, https://tkdocs.com/shipman/index-2.html

from random import random
from math import sqrt
from graphics import *  # https://mcsp.wartburg.edu/zelle/python/graphics.py


class FollowerCircle(Circle):
    """
    Creates a circle that follows another circle around at a set distance.
    Make sure to call update() every time the original circle is moved in order to move the follower as well.
    """

    def __init__(self, targetCircle, radius, targetDistance):
        super().__init__(targetCircle.getCenter(), radius)
        self.targetCircle = targetCircle
        self.targetDistance = targetDistance

    def getTargetCircle(self):
        return self.targetCircle

    def getTargetDistance(self):
        return self.targetDistance

    def update(self):
        targetPos = self.targetCircle.getCenter()
        myPos = self.getCenter()
        diff = targetPos.getX() - myPos.getX(), targetPos.getY() - myPos.getY()
        distance = sqrt(diff[0] ** 2 + diff[1] ** 2)

        if distance > 0.01:
            diffNorm = diff[0] / distance, diff[1] / distance
            diffTarget = (
                diffNorm[0] * self.targetDistance,
                diffNorm[1] * self.targetDistance,
            )
        else:
            diffTarget = 0, -self.targetDistance

        self.move(diff[0] - diffTarget[0], diff[1] - diffTarget[1])


class TrailCircle(Circle):
    """
    Creates a circle that trails behind another circle.
    It will take the other's circle last pos every frame with a moveChance chance.
    Make sure to call update() every time the original circle is moved in order to move the trail as well.
    """

    def __init__(self, targetCircle, moveChance):
        super().__init__(targetCircle.getCenter(), targetCircle.getRadius())
        self.targetCircle = targetCircle
        self.lastTargetPos = self.targetCircle.getCenter()
        self.moveChance = moveChance

    def getTargetCircle(self):
        return self.targetCircle

    def getMoveChance(self):
        return self.moveChance

    def update(self):
        if random() < self.moveChance:
            myPos = self.getCenter()
            self.move(
                self.lastTargetPos.getX() - myPos.getX(),
                self.lastTargetPos.getY() - myPos.getY(),
            )
            self.lastTargetPos = self.targetCircle.getCenter()


def main():
    win = GraphWin("Worm", 500, 500, autoflush=False)

    # HACK: Make graphics window resizable
    win.master.resizable(width=True, height=True)

    backgroundColor = [100, 160, 30]
    win.setBackground(color_rgb(*backgroundColor))

    trails = []

    def makeTrails(forCircle):
        trail = forCircle
        for j in range(2, 0, -1):
            trail = TrailCircle(trail, 0.6)
            trailColor = color_rgb(
                *[((255 - c) * (j) // 5) + c for c in backgroundColor]
            )
            trail.setFill(trailColor)
            trail.setOutline(trailColor)
            trails.append(trail)

    c = Circle(Point(100, 100), 20)
    c.setFill(color_rgb(255, 200, 255))

    follower = c
    # followers = [(follower := FollowerCircle(follower, i, i * 0.75)) for i in range(20, 0, -1)]
    followers = []
    for i in range(20, 0, -1):
        follower = FollowerCircle(follower, i, i * 0.75)
        color = int((i + 20) / 40 * 255)
        follower.setFill(color_rgb(color, color * 2 // 3, color))
        followers.append(follower)
        if i < 15:
            makeTrails(follower)

    for trail in reversed(trails):
        trail.draw(win)
    for follower in reversed(followers):
        follower.draw(win)
    c.draw(win)

    framerate = 30  # s^-1
    speed = 120  # px/s

    update()

    mousePos = Point(400, 400)
    while win.isOpen():

        # HACK: Make graphics window resizable
        size = win.master.geometry().split("+")[0].split("x")
        win.config(width=size[0], height=size[1])

        newMousePos = win.checkMouse()
        if newMousePos != None:
            mousePos = newMousePos
        centerPos = c.getCenter()
        diff = mousePos.getX() - centerPos.getX(), mousePos.getY() - centerPos.getY()
        distance = sqrt(diff[0] ** 2 + diff[1] ** 2)
        if distance > speed / framerate:
            diffNorm = diff[0] / distance, diff[1] / distance
            c.move(diffNorm[0] * speed / framerate, diffNorm[1] * speed / framerate)

        for f in followers:
            f.update()
        for t in trails:
            t.update()

        update(framerate)


main()