一、函数介绍
什么是函数?函数类似于一个水果罐头加工厂， 原料苹果从一头进场，经过厂子的处理，水果罐头就产生了。这就是函数的作用。
数学中的函数比如f(x)=x^2 即x的平方，这个函数也是个小加工厂，我们把原料x=1丢进去，那产生的产品就是f(1)=1。把原料x=2放进去,那产生的产品就是f(2)=4。
python中的函数也是同理的功能,即处理数据,返回结果。
二、函数的构成
函数基本结构由函数声明、函数名称、函数参数、函数体、返回值构成，其中函数参数和返回值是非必要的,其中参数可以是多个。
# 函数 def 函数名(param1,param2): 函数体 return 返回值
例子:
# 函数 def pingfang(x): result = x*x return result print('%s%s'%('2的平方结果:',pingfang(2)))
课外拓展: 粒子爱心
首先用cmd命令执行命令安装库函数:
pip install pygame -i https://pypi.tuna.tsinghua.edu.cn/simple/
接下来执行下面代码:
import pygame import math import random from pygame.locals import * # pip install pygame -i https://pypi.tuna.tsinghua.edu.cn/simple/ pygame.init() WIDTH, HEIGHT = 800, 600 screen = pygame.display.set_mode((WIDTH, HEIGHT)) pygame.display.set_caption("粒子爱心") BLACK = (0, 0, 0) PINK = (255, 105, 180) LIGHT_PINK = (255, 182, 193) HOT_PINK = (255, 20, 147) GALAXY_COLORS = [(180, 200, 255), (120, 160, 255), (255, 255, 255), (200, 120, 255)] angle_y = 0 pulse = 0 def is_in_3d_heart(x, z, y): scale = 0.7 x, y, z = x / scale, y / scale, z / scale term1 = (x * x + (9 * y * y) / 4.0 + z * z - 1) value = term1 * term1 * term1 - x * x * z * z * z - (9 * y * y * z * z * z) / 80.0 return value <= 0 class Particle: def __init__(self): self.reset() def reset(self): while True: x = random.uniform(-1.5, 1.5) y = random.uniform(-1.5, 1.5) z = random.uniform(-1.5, 1.5) if is_in_3d_heart(x, y, z): break self.x, self.y, self.z = x * 12, y * 12, z * 12 self.dx = random.uniform(-0.02, 0.02) self.dy = random.uniform(-0.02, 0.02) self.dz = random.uniform(-0.02, 0.02) self.base_color = random.choices([PINK, LIGHT_PINK, HOT_PINK], weights=[0.5, 0.3, 0.2])[0] self.base_size = random.uniform(1.5, 3.2) def update(self, angle_y, pulse_scale): self.x += self.dx self.y += self.dy self.z += self.dz if not is_in_3d_heart(self.x / 12, self.y / 12, self.z / 12): self.reset() x_rot = self.x * math.cos(angle_y) + self.z * math.sin(angle_y) z_rot = -self.x * math.sin(angle_y) + self.z * math.cos(angle_y) y_rot = self.y scale = 25 * pulse_scale distance = 20 x_proj = WIDTH // 2 + int(x_rot * scale) y_proj = HEIGHT // 2 - int(y_rot * scale) depth_factor = (z_rot + distance) / (2 * distance) curr_size = max(2, int(self.base_size * depth_factor * 1.5)) color_factor = min(1.0, max(0.35, depth_factor * 1.6)) r = min(255, max(0, int(self.base_color[0] * color_factor))) g = min(255, max(0, int(self.base_color[1] * color_factor))) b = min(255, max(0, int(self.base_color[2] * color_factor))) curr_color = (r, g, b) return x_proj, y_proj, curr_size, curr_color, depth_factor def draw(self, screen, angle_y, pulse_scale): x, y, size, color, depth = self.update(angle_y, pulse_scale) if 0 <= x < WIDTH and 0 <= y < HEIGHT: alpha = int(255 * (0.3 + 0.7 * depth)) color_with_alpha = (color[0], color[1], color[2], alpha) particle_surface = pygame.Surface((size * 2, size * 2), pygame.SRCALPHA) pygame.draw.circle(particle_surface, color_with_alpha, (size, size), size) screen.blit(particle_surface, (x - size, y - size)) class GalaxyParticle: def __init__(self): self.x = random.uniform(0, WIDTH) self.y = random.uniform(0, HEIGHT) self.z = random.uniform(-30, 30) self.size = random.uniform(1, 3) self.color = random.choice(GALAXY_COLORS) self.base_alpha = random.randint(12, 220) self.alpha = self.base_alpha self.speed = random.uniform(0.5, 1.5) self.angle = random.uniform(-0.2, 0.2) self.life = random.randint(60, 120) self.fade_speed = random.uniform(0.01, 0.03) def update(self): self.y -= self.speed self.x += math.sin(self.angle) * 0.5 self.size = max(0, self.size - self.fade_speed) self.life -= 1 if self.life < 30: self.alpha = int(self.alpha * self.life / 30) return self.life > 0 and self.y > 0 and self.size > 0 def draw(self, screen): particle_surface = pygame.Surface((int(self.size * 3), int(self.size * 3)), pygame.SRCALPHA) pygame.draw.circle(particle_surface, (*self.color, self.alpha), (int(self.size), int(self.size)), int(self.size)) screen.blit(particle_surface, (int(self.x - self.size), int(self.y - self.size))) # 爱心底部掉落粒子类 class ParticleDrop: def __init__(self, heart_particles): source_particle = random.choice(heart_particles) x_proj, y_proj, _, color, _ = source_particle.update(angle_y, pulse) self.x = random.randint(x_proj - 80, x_proj + 80) self.y = y_proj + 50 self.color = color self.size = random.uniform(1.5, 3.0) self.speed = random.uniform(1.0, 3.0) self.alpha = random.randint(180, 255) self.fade_speed = random.uniform(1.0, 2.5) self.horizontal_speed = random.uniform(-0.5, 0.5) self.trail = [] # 尾迹列表 def update(self): self.y += self.speed self.x += self.horizontal_speed self.alpha = max(0, self.alpha - self.fade_speed) # 记录尾迹，最多保留 1个点 self.trail.append((self.x, self.y, self.size, self.alpha)) if len(self.trail) > 200: self.trail.pop(0) return self.alpha > 0 and self.y < HEIGHT + 20 def draw(self, screen): # 绘制尾迹 for i, (tx, ty, tsize, talpha) in enumerate(self.trail): fade = int(talpha * (i + 1) / len(self.trail)) # 尾迹逐渐变淡 size = max(1, int(tsize * (i + 1) / len(self.trail))) # 尾迹逐渐变小 surf = pygame.Surface((size * 2, size * 2), pygame.SRCALPHA) pygame.draw.circle(surf, (*self.color, fade), (size, size), size) screen.blit(surf, (int(tx - size), int(ty - size))) # 绘制主粒子 particle_surface = pygame.Surface((int(self.size * 2), int(self.size * 2)), pygame.SRCALPHA) pygame.draw.circle( particle_surface, (*self.color, int(self.alpha)), (int(self.size), int(self.size)), int(self.size) ) screen.blit(particle_surface, (int(self.x - self.size), int(self.y - self.size))) # 初始化粒子系统 particles = [Particle() for _ in range(4000)] galaxy_particles = [] # 掉落粒子列表 drop_particles = [] clock = pygame.time.Clock() running = True while running: for event in pygame.event.get(): if event.type == QUIT: running = False elif event.type == pygame.KEYDOWN: if event.key == pygame.K_LEFT: angle_y -= 0.1 elif event.key == pygame.K_RIGHT: angle_y += 0.1 angle_y += 0.014 pulse = (math.sin(pygame.time.get_ticks() * 0.002) + 1) / 2 * 0.2 + 0.9 screen.fill(BLACK) fade_surface = pygame.Surface((WIDTH, HEIGHT), pygame.SRCALPHA) fade_surface.fill((0, 0, 0, 18)) screen.blit(fade_surface, (0, 0)) # 生成星河粒子 if random.random() < 0.6: galaxy_particles.append(GalaxyParticle()) # 生成掉落粒子（控制生成频率） if len(drop_particles) < 500 and random.random() < 0.98: # 限制最大粒子数并控制生成概率 drop_particles.append(ParticleDrop(particles)) # 更新和绘制星河粒子 galaxy_particles = [p for p in galaxy_particles if p.update()] for p in galaxy_particles: p.draw(screen) # 更新和绘制掉落粒子 drop_particles = [p for p in drop_particles if p.update()] for p in drop_particles: p.draw(screen) # 绘制爱心粒子 for particle in particles: particle.draw(screen, angle_y, pulse) pygame.display.flip() clock.tick(60) pygame.quit()
