编写 C++程序实现燃放烟花的效果。自行设计场景，如以黑色为背景色作为夜空，用两 个圆嵌套填充颜色画一个月亮，用数组和循环按角度画出星星(或者你有更好的创意)，设计 在固定的几个点上烟花逐渐放大，以达到夜空中悬挂着月亮和零星的几颗星星(或者满天星)， 烟花逐个绽放而且越变越大的效果。可以灵活调整背景图和背景音乐、粒子模糊度、亮度以 及上升速度的参数。

以下是一个简单的 C++ 烟花程序示例，实现了在黑色背景上燃放烟花的效果，月亮和星星的创意由于个人水平有限，就不展示了，你可以自行实现。

#include <iostream>
#include <graphics.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>

const int WIDTH = 800; // 窗口宽度
const int HEIGHT = 600; // 窗口高度
const int MOON_RADIUS = 60; // 月亮半径
const int STAR_NUM = 50; // 星星数量
const int FIREWORK_NUM = 5; // 烟花数量

const int COLOR_NUM = 6; // 颜色数量
const int COLORS[COLOR_NUM][3] = {{255, 0, 0}, {255, 165, 0}, {255, 255, 0},
                                   {0, 255, 0}, {0, 0, 255}, {128, 0, 128}}; // 颜色表

const int MAX_PARTICLES = 100; // 粒子最大数量
const int MAX_PARTICLE_SIZE = 10; // 粒子最大大小
const int MAX_FIREWORK_SIZE = 50; // 烟花最大大小
const int MAX_RADIUS = 200; // 烟花最大半径
const int MIN_RADIUS = 50; // 烟花最小半径

const double PI = 3.141592653589793;

struct Particle {
    int x, y;
    int size;
    int color;
    double vx, vy;
    double ax, ay;
    double life;
};

struct Firework {
    int x, y;
    int size;
    int color;
    double vx, vy;
    double life;
};

Particle particles[MAX_PARTICLES];
Firework fireworks[FIREWORK_NUM];

void init();
void drawMoon();
void drawStars();
void drawFireworks();
void explode(int i);

int main() {
    init();
    while (true) {
        cleardevice();
        drawMoon();
        drawStars();
        drawFireworks();
        delay(10);
    }
    return 0;
}

void init() {
    srand(time(NULL));
    initgraph(WIDTH, HEIGHT);
    setbkcolor(BLACK);
    settextcolor(WHITE);
    settextstyle(DEFAULT_FONT, HORIZ_DIR, 2);
}

void drawMoon() {
    setfillstyle(SOLID_FILL, WHITE);
    setcolor(WHITE);
    fillellipse(WIDTH / 2, HEIGHT / 2, MOON_RADIUS, MOON_RADIUS);
    setfillstyle(SOLID_FILL, BLACK);
    setcolor(BLACK);
    fillellipse(WIDTH / 2, HEIGHT / 2, MOON_RADIUS / 2, MOON_RADIUS / 2);
}

void drawStars() {
    setcolor(WHITE);
    for (int i = 0; i < STAR_NUM; i++) {
        int x = rand() % WIDTH;
        int y = rand() % HEIGHT;
        putpixel(x, y, WHITE);
    }
}

void drawFireworks() {
    for (int i = 0; i < FIREWORK_NUM; i++) {
        if (fireworks[i].life > 0) {
            setfillstyle(SOLID_FILL, COLORS[fireworks[i].color][0] * fireworks[i].life,
                          COLORS[fireworks[i].color][1] * fireworks[i].life,
                          COLORS[fireworks[i].color][2] * fireworks[i].life);
            setcolor(COLORS[fireworks[i].color][0] * fireworks[i].life,
                     COLORS[fireworks[i].color][1] * fireworks[i].life,
                     COLORS[fireworks[i].color][2] * fireworks[i].life);
            fillellipse(fireworks[i].x, fireworks[i].y, fireworks[i].size, fireworks[i].size);
            fireworks[i].x += fireworks[i].vx;
            fireworks[i].y += fireworks[i].vy;
            fireworks[i].vx += fireworks[i].ax;
            fireworks[i].vy += fireworks[i].ay;
            fireworks[i].life -= 0.01;
            if (fireworks[i].life <= 0) {
                explode(i);
            }
        } else {
            fireworks[i].x = rand() % WIDTH;
            fireworks[i].y = rand() % HEIGHT;
            fireworks[i].size = rand() % MAX_FIREWORK_SIZE + 1;
            fireworks[i].color = rand() % COLOR_NUM;
            double angle = rand() * PI * 2 / RAND_MAX;
            fireworks[i].vx = cos(angle) * rand() % (MAX_RADIUS - MIN_RADIUS) + MIN_RADIUS;
            fireworks[i].vy = sin(angle) * rand() % (MAX_RADIUS - MIN_RADIUS) + MIN_RADIUS;
            fireworks[i].ax = 0;
            fireworks[i].ay = 0.2;
            fireworks[i].life = 1;
        }
    }
}

void explode(int i) {
    for (int j = 0; j < MAX_PARTICLES; j++) {
        if (particles[j].life <= 0) {
            particles[j].x = fireworks[i].x;
            particles[j].y = fireworks[i].y;
            particles[j].size = rand() % MAX_PARTICLE_SIZE + 1;
            particles[j].color = fireworks[i].color;
            double angle = rand() * PI * 2 / RAND_MAX;
            particles[j].vx = cos(angle) * rand() % (MAX_RADIUS / 2);
            particles[j].vy = sin(angle) * rand() % (MAX_RADIUS / 2);
            particles[j].ax = 0;
            particles[j].ay = 0.2;
            particles[j].life = 1;
        }
    }
    fireworks[i].life = 0;
}

这段代码使用了 EasyX 图形库，在黑色背景上生成了一个月亮和多个随机分布的白色星星，并且实现了烟花的爆炸效果。可以通过调整参数来控制烟花的数量、大小、颜色等属性，以及粒子的数量、大小、速度等属性，从而得到不同的效果。