宜配屋

无意中看到一段用Tkinter库写的放烟花的程序，就跟着跑了一遍。

设计理念：通过让画面上一个粒子分裂为X数量的粒子来模拟爆炸效果。粒子会发生“膨胀”，意思是它们会以恒速移动且相互之间的角度相等。这样就能让我们以一个向外膨胀的圆圈形式模拟出烟花绽放的画面。经过一定时间后，粒子会进入“自由落体”阶段，也就是由于重力因素它们开始坠落到地面，仿若绽放后熄灭的烟花。

首先我们写一个粒子类，表示烟花事件中的每个粒子，包含大小，颜色，位置，速度等属性以及粒子经历的三个阶段的函数，即：膨胀、坠落、消失。

'''
particles 类
粒子在空中随机生成随机，变成一个圈、下坠、消失
属性:
 - id: 粒子的id
 - x, y: 粒子的坐标
 - vx, vy: 在坐标的变化速度
 - total: 总数
 - age: 粒子存在的时长
 - color: 颜色
 - cv: 画布
 - lifespan: 最高存在时长
'''
 
 
class Particle:
 
 def __init__(self, cv, idx, total, explosion_speed, x=0., y=0., vx=0., vy=0., size=2., color='red', lifespan=2,
     **kwargs):
  self.id = idx
  self.x = x
  self.y = y
  self.initial_speed = explosion_speed
  self.vx = vx
  self.vy = vy
  self.total = total
  self.age = 0
  self.color = color
  self.cv = cv
  self.cid = self.cv.create_oval(
   x - size, y - size, x + size,
   y + size, fill=self.color)
  self.lifespan = lifespan
 
 def update(self, dt):
  self.age += dt
 
  # 粒子范围扩大
  if self.alive() and self.expand():
   move_x = cos(radians(self.id * 360 / self.total)) * self.initial_speed
   move_y = sin(radians(self.id * 360 / self.total)) * self.initial_speed
   self.cv.move(self.cid, move_x, move_y)
   self.vx = move_x / (float(dt) * 1000)
 
  # 以自由落体坠落
  elif self.alive():
   move_x = cos(radians(self.id * 360 / self.total))
   # we technically don't need to update x, y because move will do the job
   self.cv.move(self.cid, self.vx + move_x, self.vy + GRAVITY * dt)
   self.vy += GRAVITY * dt
 
  # 移除超过最高时长的粒子
  elif self.cid is not None:
   cv.delete(self.cid)
   self.cid = None
 
 # 扩大的时间
 def expand (self):
  return self.age <= 1.2
 
 # 粒子是否在最高存在时长内
 def alive(self):
  return self.age <= self.lifespan

接下来我们需要创建一列列表，每个子列表是一个烟花，其包含一列粒子，每个列表中的粒子有相同的x,y坐标、大小、颜色、初始速度。

源码如下：

import tkinter as tk
from PIL import Image, ImageTk
from time import time, sleep
from random import choice, uniform, randint
from math import sin, cos, radians
 
# 模拟重力
GRAVITY = 0.05
# 颜色选项（随机或者按顺序）
colors = ['red', 'blue', 'yellow', 'white', 'green', 'orange', 'purple', 'seagreen', 'indigo', 'cornflowerblue']
 
'''
particles 类
粒子在空中随机生成随机，变成一个圈、下坠、消失
属性:
 - id: 粒子的id
 - x, y: 粒子的坐标
 - vx, vy: 在坐标的变化速度
 - total: 总数
 - age: 粒子存在的时长
 - color: 颜色
 - cv: 画布
 - lifespan: 最高存在时长
'''
 
 
class Particle:
 
 def __init__(self, cv, idx, total, explosion_speed, x=0., y=0., vx=0., vy=0., size=2., color='red', lifespan=2,
     **kwargs):
  self.id = idx
  self.x = x
  self.y = y
  self.initial_speed = explosion_speed
  self.vx = vx
  self.vy = vy
  self.total = total
  self.age = 0
  self.color = color
  self.cv = cv
  self.cid = self.cv.create_oval(
   x - size, y - size, x + size,
   y + size, fill=self.color)
  self.lifespan = lifespan
 
 def update(self, dt):
  self.age += dt
 
  # 粒子范围扩大
  if self.alive() and self.expand():
   move_x = cos(radians(self.id * 360 / self.total)) * self.initial_speed
   move_y = sin(radians(self.id * 360 / self.total)) * self.initial_speed
   self.cv.move(self.cid, move_x, move_y)
   self.vx = move_x / (float(dt) * 1000)
 
  # 以自由落体坠落
  elif self.alive():
   move_x = cos(radians(self.id * 360 / self.total))
   # we technically don't need to update x, y because move will do the job
   self.cv.move(self.cid, self.vx + move_x, self.vy + GRAVITY * dt)
   self.vy += GRAVITY * dt
 
  # 移除超过最高时长的粒子
  elif self.cid is not None:
   cv.delete(self.cid)
   self.cid = None
 
 # 扩大的时间
 def expand (self):
  return self.age <= 1.2
 
 # 粒子是否在最高存在时长内
 def alive(self):
  return self.age <= self.lifespan
 
'''
循环调用保持不停
'''
def simulate(cv):
 t = time()
 explode_points = []
 wait_time = randint(10, 100)
 numb_explode = randint(6, 10)
 # 创建一个所有粒子同时扩大的二维列表
 for point in range(numb_explode):
  objects = []
  x_cordi = randint(50, 550)
  y_cordi = randint(50, 150)
  speed = uniform(0.5, 1.5)
  size = uniform(0.5, 3)
  color = choice(colors)
  explosion_speed = uniform(0.2, 1)
  total_particles = randint(10, 50)
  for i in range(1, total_particles):
   r = Particle(cv, idx=i, total=total_particles, explosion_speed=explosion_speed, x=x_cordi, y=y_cordi,
       vx=speed, vy=speed, color=color, size=size, lifespan=uniform(0.6, 1.75))
   objects.append(r)
  explode_points.append(objects)
 
 total_time = .0
 # 1.8s内一直扩大
 while total_time < 1.8:
  sleep(0.01)
  tnew = time()
  t, dt = tnew, tnew - t
  for point in explode_points:
   for item in point:
    item.update(dt)
  cv.update()
  total_time += dt
 # 循环调用
 root.after(wait_time, simulate, cv)
 
 
def close(*ignore):
 """退出程序、关闭窗口"""
 global root
 root.quit()
 
 
if __name__ == '__main__':
 root = tk.Tk()
 cv = tk.Canvas(root, height=360, width=480)
 # 选一个好看的背景会让效果更惊艳！
 image = Image.open("./image.jpg")
 photo = ImageTk.PhotoImage(image)
 
 cv.create_image(0, 0, image=photo, anchor='nw')
 cv.pack()
 
 root.protocol("WM_DELETE_WINDOW", close)
 root.after(100, simulate, cv)
 root.mainloop()

效果图（背景请忽略哈哈）：