今天是2022
的第三天,到了这个时间点,部分小伙伴已经开始复盘这一年的得与失。比如今年增加了多少技能点,看了多少本书,写了多少篇文章或者年前的小目标实现进度大概多少等等;做一个象征性的年终总结来告别2021,迎接2022:

本篇文章,带大家用 Python 制作一个炫酷烟花秀,来迎接即将到来的元旦佳节。开始之前先看一下最终效果

环境介绍:

语言:Python;

库:Pygame;

<>原理介绍

在介绍代码之前,先介绍下 Pygame 绘制烟花的基本原理,烟花从发射到绽放一共分为三个阶段:

1, 发射阶段 :在这一阶段烟花的形状是线性向上,通过设定一组大小不同、颜色不同的点来模拟“向上发射” 的运动运动,运动过程中
5个点被赋予不同大小的加速度,随着时间推移,后面的点会赶上前面的点,最终所有点会汇聚在一起,处于绽放准备阶段 ;

2, 烟花绽放 :烟花绽放这个阶段,是由一个点分散多个点向不同方向发散,并且每个点的移动轨迹可需要被记录,目的是为了追踪整个绽放轨迹。

3, 烟花凋零
,此阶段负责描绘绽放后烟花的效果,绽放后的烟花,而在每一时刻点的下降速度和亮度(代码中也叫透明度)是不一样的,因此在代码里,将烟花绽放后将每个点赋予两个属性:分别为重力向量和生命周期,来模拟烟花在不同时期时不同的展现效果,

<>代码实操

代码部分将烟花封装为三个类:

Firework : 烟花整体;

Particle : 烟花粒子(包含轨迹)

Trail : 烟花轨迹,本质上是一个点 。

三个类之间的关系为:一个Firework 由多个 Particle 构成,而一个 Particle 由多个 Trail 构成

首先设置全局变量,例如重力向量,窗口大小,Trail 的颜色列表(多为灰色或白色)以及不同状态下 Trail 之间间隔
gravity = vector(0, 0.3)DISPLAY_WIDTH = DISPLAY_HEIGHT = 800trail_colours =
[(45, 45, 45), (60, 60, 60), (75, 75, 75), (125, 125, 125), (150, 150,
150)]dynamic_offset = 1static_offset = 3
创建 Trail 类,定义 show 方法绘制轨迹 、get_pos 实时获取轨迹坐标
class Trail: def __init__(self, n, size, dynamic): self.pos_in_line = n
self.pos = vector(-10, -10) self.dynamic = dynamic if self.dynamic: self.colour
= trail_colours[n] self.size = int(size - n / 2) else: self.colour = (255, 255,
200) self.size = size - 2 if self.size < 0: self.size = 0 def get_pos(self, x,
y): self.pos = vector(x, y) def show(self, win): pygame.draw.circle(win,
self.colour, (int(self.pos.x), int(self.pos.y)), self.size)
Particle 类核心代码
class Particle: def __init__(self, x, y, firework, colour): self.firework =
firework self.pos = vector(x, y) self.origin = vector(x, y) self.radius = 20
self.remove = False self.explosion_radius = randint(5, 18) self.life = 0
self.acc = vector(0, 0) # trail variables self.trails = [] # stores the
particles trail objects self.prev_posx = [-10] * 10 # stores the 10 last
positions self.prev_posy = [-10] * 10 # stores the 10 last positions if
self.firework: self.vel = vector(0, -randint(17, 20)) self.size = 5 self.colour
= colour for i in range(5): self.trails.append(Trail(i, self.size, True)) else:
self.vel = vector(uniform(-1, 1), uniform(-1, 1)) self.vel.x *= randint(7,
self.explosion_radius + 2) self.vel.y *= randint(7, self.explosion_radius + 2)
# 向量 self.size = randint(2, 4) self.colour = choice(colour) # 5 个 tails总计 for i
in range(5): self.trails.append(Trail(i, self.size, False)) def
apply_force(self, force): self.acc += force def move(self): if not
self.firework: self.vel.x *= 0.8 self.vel.y *= 0.8 self.vel += self.acc
self.pos += self.vel self.acc *= 0 if self.life == 0 and not self.firework: #
check if particle is outside explosion radius distance = math.sqrt((self.pos.x
- self.origin.x) ** 2 + (self.pos.y - self.origin.y) ** 2) if distance >
self.explosion_radius: self.remove = True self.decay() self.trail_update()
self.life += 1 def show(self, win): pygame.draw.circle(win, (self.colour[0],
self.colour[1], self.colour[2], 0), (int(self.pos.x), int(self.pos.y)),
self.size) def decay(self): # random decay of the particles if 50 > self.life >
10: # early stage their is a small chance of decay ran = randint(0, 30) if ran
== 0: self.remove = True elif self.life > 50: ran = randint(0, 5) if ran == 0:
self.remove = True
Firework 类核心代码
class Firework: def __init__(self): # 随机颜色 self.colour = (randint(0, 255),
randint(0, 255), randint(0, 255)) self.colours = ( (randint(0, 255), randint(0,
255), randint(0, 255)), (randint(0, 255), randint(0, 255), randint(0, 255)),
(randint(0, 255), randint(0, 255), randint(0, 255))) self.firework =
Particle(randint(0, DISPLAY_WIDTH), DISPLAY_HEIGHT, True, self.colour) #
Creates the firework particle self.exploded = False self.particles = []
self.min_max_particles = vector(100, 225) def update(self, win): # called every
frame if not self.exploded: self.firework.apply_force(gravity)
self.firework.move() for tf in self.firework.trails: tf.show(win)
self.show(win) if self.firework.vel.y >= 0: self.exploded = True self.explode()
else: for particle in self.particles: particle.apply_force(vector(gravity.x +
uniform(-1, 1) / 20, gravity.y / 2 + (randint(1, 8) / 100))) particle.move()
for t in particle.trails: t.show(win) particle.show(win) def remove(self): if
self.exploded: for p in self.particles: if p.remove is True:
self.particles.remove(p) if len(self.particles) == 0: return True else: return
False
最后,写一个 main 方法来对 pygame 环境进行初始化,例如背景图片,文字,设置页面刷新间隔,程序中设置的每 60ms 刷新一次。
pygame.display.set_caption("Fireworks in Pygame") # 标题 background =
pygame.image.load("img/1.png") # 背景 myfont =
pygame.font.Font("img/simkai.ttf",80) myfont1 =
pygame.font.Font("img/simkai.ttf", 30) testsurface =
myfont.render("元旦快乐",False,(255,255,255)) testsurface1 =
myfont1.render("By:小张Python", False, (255, 255, 255)) # pygame.image.load("")
win = pygame.display.set_mode((DISPLAY_WIDTH, DISPLAY_HEIGHT)) #
win.blit(background) clock = pygame.time.Clock() fireworks = [Firework() for i
in range(2)] # create the first fireworks running = True while running:
clock.tick(60) win.fill((20, 20, 30)) # draw background
win.blit(background,(0,0)) win.blit(testsurface,(200,200))
win.blit(testsurface1, (300,200)) if randint(0, 20) == 1: # create new firework
fireworks.append(Firework()) update(win, fireworks)
另外程序中会对你的按键命令进行监控:

* 当按下键 1时 ,会立即生成一个新的 “烟花”;
* 当按下键 2时,会同时生成 10 个 “烟花” for event in pygame.event.get(): if event.type ==
pygame.QUIT: running = False if event.type == pygame.KEYDOWN: # Change game
speed with number keys if event.key == pygame.K_1: # 按下 1
fireworks.append(Firework()) if event.key == pygame.K_2: # 按下 2 加入10个烟花 for i
in range(10): fireworks.append(Firework())
总的来说,整个小案例的代码量不算很多,一共250行左右,但案例中涉及到较为复杂的绘制逻辑和抽象的类之间的封装关系,因此大家理解代码相对会需要耗费点时间。

写到这里,本篇文章算基本结束了,主要介绍就是如何用 Pygame
来模拟一个烟花绽放过程,核心内容大致两点:第一,如何用绘制点的方式来模拟烟花绽放运动轨迹;第二 介绍Pygame
一些基础用法:替换背景,绘制文字,更新状态等功能;

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