310 lines
10 KiB
JavaScript
310 lines
10 KiB
JavaScript
/**
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* 文件功能：聊天室烟花特效（真实感版本）
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*
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* 完整模拟真实烟花流程：
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* 1. 火箭从底部带着尾迹飞向目标高度
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* 2. 到达位置后爆炸，产生 3 种形态：球形/柳叶/星形
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* 3. 每颗粒子带历史轨迹尾巴，随重力下坠并消散
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*
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* 全程透明 Canvas，不遮挡聊天背景。
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*/
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const FireworksEffect = (() => {
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// ─── 火箭类 ──────────────────────────────────────────
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class Rocket {
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/**
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* @param {number} x 发射 x 位置
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* @param {number} targetY 爆炸目标高度（距顶部比例）
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* @param {string} color 爆炸颜色
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* @param {string} type 爆炸类型：sphere / willow / ring
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*/
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constructor(x, targetY, color, type, canvasHeight) {
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this.x = x;
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this.y = canvasHeight; // 从画布底部出发
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this.targetY = targetY;
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this.color = color;
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this.type = type;
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// 根据飞行距离动态计算初始速度，保证必然到达目标高度
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// 等比级数求和：total = vy / (1 - 0.98) = vy × 50
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// 加 10%~20% 余量，使火箭略微超过目标再触发爆炸（更真实）
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const dist = canvasHeight - targetY;
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this.vy = -(dist / 50) * (1.1 + Math.random() * 0.15);
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this.trail = []; // 尾迹历史坐标
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this.exploded = false;
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this.done = false;
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}
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/** 更新火箭位置，到达目标高度后标记为已爆炸 */
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update() {
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this.trail.push({ x: this.x, y: this.y });
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if (this.trail.length > 10) this.trail.shift();
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this.y += this.vy;
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this.vy *= 0.98; // 轻微减速（仿真阻力）
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if (this.y <= this.targetY) {
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this.exploded = true;
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this.done = true;
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}
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}
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/** 绘制火箭（白色头部 + 橙色尾迹） */
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draw(ctx) {
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// 尾迹（由新到旧逐渐变淡）
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for (let i = 0; i < this.trail.length; i++) {
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const a = (i / this.trail.length) * 0.6;
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ctx.save();
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ctx.globalAlpha = a;
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ctx.fillStyle = "#ffaa44";
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ctx.shadowColor = "#ff6600";
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ctx.shadowBlur = 6;
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ctx.beginPath();
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ctx.arc(this.trail[i].x, this.trail[i].y, 2, 0, Math.PI * 2);
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ctx.fill();
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ctx.restore();
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}
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// 火箭头部（亮白色光点）
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ctx.save();
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ctx.fillStyle = "#ffffff";
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ctx.shadowColor = "#ffcc88";
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ctx.shadowBlur = 10;
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ctx.beginPath();
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ctx.arc(this.x, this.y, 3, 0, Math.PI * 2);
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ctx.fill();
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ctx.restore();
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}
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}
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// ─── 爆炸粒子类 ──────────────────────────────────────
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class Particle {
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/**
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* @param {number} x 爆炸中心 x
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* @param {number} y 爆炸中心 y
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* @param {string} color 粒子颜色
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* @param {string} type 爆炸类型
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* @param {number} angle 发射角度（ring 类型用）
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*/
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constructor(x, y, color, type, angle) {
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this.x = x;
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this.y = y;
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this.color = color;
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this.trail = [];
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let speed;
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if (type === "ring") {
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// 环形：均匀角度，固定速度
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speed = 5 + Math.random() * 2;
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this.vx = Math.cos(angle) * speed;
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this.vy = Math.sin(angle) * speed;
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this.gravity = 0.06;
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this.decay = 0.014;
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this.radius = 2;
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} else if (type === "willow") {
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// 柳叶：慢速，在空中下垂
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speed = Math.random() * 3 + 1;
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const a = Math.random() * Math.PI * 2;
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this.vx = Math.cos(a) * speed;
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this.vy = Math.sin(a) * speed - 2; // 初速稍微向上
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this.gravity = 0.07;
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this.decay = 0.009; // 衰减慢，拖出长尾
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this.radius = 1.5;
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} else {
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// sphere：标准球形爆炸
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speed = Math.random() * 6 + 2;
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const a = Math.random() * Math.PI * 2;
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this.vx = Math.cos(a) * speed;
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this.vy = Math.sin(a) * speed;
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this.gravity = 0.1;
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this.decay = 0.016;
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this.radius = Math.random() * 2 + 1.5;
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}
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this.alpha = 1;
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// 部分粒子有闪烁效果
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this.sparkle = Math.random() > 0.6;
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this.frame = 0;
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}
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/** 更新粒子物理状态 */
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update() {
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this.frame++;
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// 保存轨迹历史（尾迹长度由透明度控制）
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this.trail.push({ x: this.x, y: this.y });
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if (this.trail.length > 6) this.trail.shift();
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this.vy += this.gravity;
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this.x += this.vx;
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this.y += this.vy;
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this.vx *= 0.985;
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this.vy *= 0.985;
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// 闪烁：每隔几帧透明度轻微抖动
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if (this.sparkle && this.frame % 4 === 0) {
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this.alpha = Math.max(
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0,
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this.alpha - this.decay * (0.5 + Math.random()),
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);
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} else {
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this.alpha -= this.decay;
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}
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}
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/** 绘制粒子及其运动轨迹尾迹 */
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draw(ctx) {
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// 绘制尾迹
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for (let i = 0; i < this.trail.length; i++) {
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const a = (i / this.trail.length) * this.alpha * 0.45;
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ctx.save();
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ctx.globalAlpha = a;
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ctx.fillStyle = this.color;
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ctx.beginPath();
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ctx.arc(
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this.trail[i].x,
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this.trail[i].y,
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this.radius * 0.55,
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0,
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Math.PI * 2,
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);
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ctx.fill();
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ctx.restore();
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}
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// 绘制粒子主体（带发光）
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ctx.save();
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ctx.globalAlpha = Math.max(0, this.alpha);
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ctx.fillStyle = this.color;
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ctx.shadowColor = this.color;
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ctx.shadowBlur = 8;
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ctx.beginPath();
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ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2);
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ctx.fill();
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ctx.restore();
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}
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get alive() {
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return this.alpha > 0.01;
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}
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}
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// ─── 预定义颜色 / 类型 ───────────────────────────────
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const COLORS = [
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"#ff2200",
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"#ff7700",
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"#ffcc00",
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"#00dd44",
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"#cc00ff",
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"#ff0088",
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"#00bbff",
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"#ff4488",
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"#ffaa00",
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];
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const TYPES = ["sphere", "willow", "ring"];
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/**
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* 生成一批爆炸粒子
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*
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* @param {number} x 爆炸中心 x
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* @param {number} y 爆炸中心 y
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* @param {string} color 颜色
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* @param {string} type 爆炸类型
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* @returns {Particle[]}
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*/
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function _burst(x, y, color, type) {
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const particles = [];
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const count = type === "ring" ? 80 : type === "willow" ? 120 : 100;
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if (type === "ring") {
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// 环形：均匀分布
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for (let i = 0; i < count; i++) {
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const angle = ((Math.PI * 2) / count) * i;
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particles.push(new Particle(x, y, color, type, angle));
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}
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} else {
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for (let i = 0; i < count; i++) {
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particles.push(new Particle(x, y, color, type, 0));
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}
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// willow/sphere 中心加一颗白色闪光核心粒子
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for (let i = 0; i < 10; i++) {
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const p = new Particle(x, y, "#ffffff", "sphere", 0);
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p.decay *= 2;
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p.radius = 1;
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particles.push(p);
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}
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}
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return particles;
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}
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/**
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* 启动烟花特效
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*
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* @param {HTMLCanvasElement} canvas 全屏 Canvas
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* @param {Function} onEnd 特效结束回调
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*/
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function start(canvas, onEnd) {
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const ctx = canvas.getContext("2d");
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const w = canvas.width;
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const h = canvas.height;
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const DURATION = 10000;
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let rockets = [];
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let particles = [];
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let animId = null;
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let launchCnt = 0;
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const MAX_LAUNCHES = 12;
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// 定时发射火箭
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const launchInterval = setInterval(() => {
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if (launchCnt >= MAX_LAUNCHES) {
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clearInterval(launchInterval);
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return;
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}
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const x = w * (0.15 + Math.random() * 0.7);
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const ty = h * (0.08 + Math.random() * 0.45);
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const color = COLORS[Math.floor(Math.random() * COLORS.length)];
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const type = TYPES[Math.floor(Math.random() * TYPES.length)];
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const rocket = new Rocket(x, ty, color, type, h); // 传入画布高度
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rockets.push(rocket);
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launchCnt++;
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}, 600);
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const startTime = performance.now();
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function animate(now) {
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ctx.clearRect(0, 0, w, h);
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// 更新和绘制火箭
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for (let i = rockets.length - 1; i >= 0; i--) {
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const r = rockets[i];
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if (r.done) {
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// 火箭爆炸：生成粒子
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const burst = _burst(r.x, r.y, r.color, r.type);
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particles = particles.concat(burst);
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rockets.splice(i, 1);
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} else {
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r.update();
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r.draw(ctx);
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}
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}
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// 更新和绘制粒子
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particles = particles.filter((p) => p.alive);
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particles.forEach((p) => {
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p.update();
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p.draw(ctx);
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});
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if (now - startTime < DURATION) {
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animId = requestAnimationFrame(animate);
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} else {
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clearInterval(launchInterval);
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cancelAnimationFrame(animId);
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ctx.clearRect(0, 0, w, h);
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onEnd();
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}
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}
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animId = requestAnimationFrame(animate);
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}
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return { start };
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})();
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