目录
一、程序代码
二、代码原理
三、运行效果
一、程序代码
跨年烟花秀 * {position: relative;box-sizing: border-box;}html,body {height: 100%;}html {background-color: #000;}body {overflow: hidden;color: rgba(255, 255, 255, 0.5);font-family: "Russo One", arial, sans-serif;line-height: 1.25;letter-spacing: 0.06em;}.hide {opacity: 0;visibility: hidden;}.remove {display: none;}.blur {filter: blur(12px);}.container {height: 100%;display: flex;justify-content: center;align-items: center;}#loading-init {width: 100%;align-self: center;text-align: center;font-size: 2em;}#stage-container {overflow: hidden;box-sizing: initial;border: 1px solid #222;margin: -1px;}#canvas-container {width: 100%;height: 100%;transition: filter 0.3s;}#canvas-container canvas {position: absolute;mix-blend-mode: lighten;}#controls {position: absolute;top: 0;width: 100%;padding-bottom: 50px;display: flex;justify-content: space-between;transition: opacity 0.3s, visibility 0.3s;}@media (min-width: 800px) {#controls {visibility: visible;}#controls.hide:hover {opacity: 1;}}#menu {display: flex;flex-direction: column;justify-content: center;align-items: center;position: absolute;top: 0;bottom: 0;width: 100%;background-color: rgba(0, 0, 0, 0.42);transition: opacity 0.3s, visibility 0.3s;}#menu__header {padding: 20px 0 44px;font-size: 2em;text-transform: uppercase;}#menu form {width: 240px;padding: 0 20px;overflow: auto;}#menu .form-option {margin: 20px 0;}#menu .form-option label {text-transform: uppercase;}#menu .form-option--select label {display: block;margin-bottom: 6px;}#menu .form-option--select select {display: block;width: 100%;height: 30px;font-size: 1rem;font-family: "Russo One", arial, sans-serif;color: rgba(255, 255, 255, 0.5);letter-spacing: 0.06em;background-color: transparent;border: 1px solid rgba(255, 255, 255, 0.5);}#menu .form-option--select select option {background-color: black;}#menu .form-option--checkbox label {display: flex;align-items: center;transition: opacity 0.3s;-webkit-user-select: none;-moz-user-select: none;-ms-user-select: none;user-select: none;}#menu .form-option--checkbox input {display: block;width: 20px;height: 20px;margin-right: 8px;opacity: 0.5;}@media (max-width: 800px) {#menu .form-option select,#menu .form-option input {outline: none;}}#close-menu-btn {position: absolute;top: 0;right: 0;}.btn {opacity: 0.16;width: 44px;height: 44px;display: flex;-webkit-user-select: none;-moz-user-select: none;-ms-user-select: none;user-select: none;cursor: default;transition: opacity 0.3s;}.btn--bright {opacity: 0.5;}@media (min-width: 800px) {.btn:hover {opacity: 0.32;}.btn--bright:hover {opacity: 0.75;}}.btn svg {display: block;margin: auto;}惊喜即将来临！Settings'use strict';console.clear();const IS_MOBILE = window.innerWidth 800;const IS_HEADER = IS_DESKTOP && window.innerHeight listener(this.state))},state: {paused: false,longExposure: false,menuOpen: false,config: {shell: 'Random',size: IS_DESKTOP && !IS_HEADER ? '3' : '1',autoLaunch: true,finale: false,hideControls: IS_HEADER}},setState(nextState) {this.state = Object.assign({}, this.state, nextState);this._dispatch();this.persist();},subscribe(listener) {this._listeners.add(listener);return () => this._listeners.remove(listener);},// Load / persist select state to localStorageload() {if (localStorage.getItem('schemaVersion') === '1') {this.state.config.size = JSON.parse(localStorage.getItem('configSize'));this.state.config.hideControls = JSON.parse(localStorage.getItem('hideControls'));}},persist() {localStorage.setItem('schemaVersion', '1');localStorage.setItem('configSize', JSON.stringify(this.state.config.size));localStorage.setItem('hideControls', JSON.stringify(this.state.config.hideControls));}};if (!IS_HEADER) {store.load();}// Actions// ---------function togglePause(toggle) {if (typeof toggle === 'boolean') {store.setState({ paused: toggle });} else {store.setState({ paused: !store.state.paused });}}function toggleLongExposure(toggle) {if (typeof toggle === 'boolean') {store.setState({ longExposure: toggle });} else {store.setState({ longExposure: !store.state.longExposure });}}function toggleMenu(toggle) {if (typeof toggle === 'boolean') {store.setState({ menuOpen: toggle });} else {store.setState({ menuOpen: !store.state.menuOpen });}}function updateConfig(nextConfig) {nextConfig = nextConfig || getConfigFromDOM();store.setState({config: Object.assign({}, store.state.config, nextConfig)});}// Selectors// -----------const canInteract = () => !store.state.paused && !store.state.menuOpen;const shellNameSelector = () => store.state.config.shell;// Converts shell size to number.const shellSizeSelector = () => +store.state.config.size;const finaleSelector = () => store.state.config.finale;// Render app UI / keep in sync with stateconst appNodes = {stageContainer: '#stage-container',canvasContainer: '#canvas-container',controls: '#controls',menu: '#menu',pauseBtn: '#pause-btn',pauseBtnSVG: '#pause-btn use',shutterBtn: '#shutter-btn',shutterBtnSVG: '#shutter-btn use',shellType: '#shell-type',shellSize: '#shell-size',autoLaunch: '#auto-launch',autoLaunchLabel: '#auto-launch-label',finaleMode: '#finale-mode',finaleModeLabel: '#finale-mode-label',hideControls: '#hide-controls',hideControlsLabel: '#hide-controls-label'};// Convert appNodes selectors to dom nodesObject.keys(appNodes).forEach(key => {appNodes[key] = document.querySelector(appNodes[key]);});// Remove loading statedocument.getElementById('loading-init').remove();appNodes.stageContainer.classList.remove('remove');// First render is called in init()function renderApp(state) {appNodes.pauseBtnSVG.setAttribute('href', `#icon-${state.paused ? 'play' : 'pause'}`);appNodes.shutterBtnSVG.setAttribute('href', `#icon-shutter-${state.longExposure ? 'fast' : 'slow'}`);appNodes.controls.classList.toggle('hide', state.menuOpen || state.config.hideControls);appNodes.canvasContainer.classList.toggle('blur', state.menuOpen);appNodes.menu.classList.toggle('hide', !state.menuOpen);appNodes.finaleModeLabel.style.opacity = state.config.autoLaunch ? 1 : 0.32;appNodes.shellType.value = state.config.shell;appNodes.shellSize.value = state.config.size;appNodes.autoLaunch.checked = state.config.autoLaunch;appNodes.finaleMode.checked = state.config.finale;appNodes.hideControls.checked = state.config.hideControls;}store.subscribe(renderApp);function getConfigFromDOM() {return {shell: appNodes.shellType.value,size: appNodes.shellSize.value,autoLaunch: appNodes.autoLaunch.checked,finale: appNodes.finaleMode.checked,hideControls: appNodes.hideControls.checked};};const updateConfigNoEvent = () => updateConfig();appNodes.shellType.addEventListener('input', updateConfigNoEvent);appNodes.shellSize.addEventListener('input', updateConfigNoEvent);appNodes.autoLaunchLabel.addEventListener('click', () => setTimeout(updateConfig, 0));appNodes.finaleModeLabel.addEventListener('click', () => setTimeout(updateConfig, 0));appNodes.hideControlsLabel.addEventListener('click', () => setTimeout(updateConfig, 0));// Constant derivationsconst COLOR_NAMES = Object.keys(COLOR);const COLOR_CODES = COLOR_NAMES.map(colorName => COLOR[colorName]);// Invisible stars need an indentifier, even through they won't be rendered - physics still apply.const COLOR_CODES_W_INVIS = [...COLOR_CODES, INVISIBLE];// Tuples is a map keys by color codes (hex) with values of { r, g, b } tuples (still just objects).const COLOR_TUPLES = {};COLOR_CODES.forEach(hex => {COLOR_TUPLES[hex] = {r: parseInt(hex.substr(1, 2), 16),g: parseInt(hex.substr(3, 2), 16),b: parseInt(hex.substr(5, 2), 16),};});// Get a random color.function randomColorSimple() {return COLOR_CODES[Math.random() * COLOR_CODES.length | 0];}// Get a random color, with some customization options available.let lastColor;function randomColor(options) {const notSame = options && options.notSame;const notColor = options && options.notColor;const limitWhite = options && options.limitWhite;let color = randomColorSimple();// limit the amount of white chosen randomlyif (limitWhite && color === COLOR.White && Math.random() < 0.6) {color = randomColorSimple();}if (notSame) {while (color === lastColor) {color = randomColorSimple();}}else if (notColor) {while (color === notColor) {color = randomColorSimple();}}lastColor = color;return color;}function whiteOrGold() {return Math.random() {const glitter = Math.random() < 0.25;const singleColor = Math.random() < 0.68;const color = singleColor ? randomColor({ limitWhite: true }) : [randomColor(), randomColor({ notSame: true })];const pistil = singleColor && Math.random() < 0.42;const pistilColor = makePistilColor(color);const streamers = !pistil && color !== COLOR.White && Math.random() ({size: 250 + size * 75,starDensity: 0.6,starLife: 1800 + size * 200,glitter: 'heavy'});const ringShell = (size = 1) => {const color = randomColor();const pistil = Math.random() {const color = randomColor({ limitWhite: true });return {size: 300 + size * 100,starLife: 900 + size * 200,starLifeVariation: 0.22,color,crossette: true,pistil: Math.random() ({size: 300 + size * 120,starDensity: 0.38,starLife: 500 + size * 50,starLifeVariation: 0.5,color: Math.random() < 0.65 ? 'random' : (Math.random() ({color: INVISIBLE,size: 300 + size * 120,starDensity: 0.38,starLife: 500 + size * 50,starLifeVariation: 0.5,glitter: 'medium',glitterColor: COLOR.Gold,fallingLeaves: true});const willowShell = (size = 1) => ({size: 300 + size * 100,starDensity: 0.7,starLife: 3000 + size * 300,glitter: 'willow',glitterColor: COLOR.Gold,color: INVISIBLE});const crackleShell = (size = 1) => {// favor goldconst color = Math.random() < 0.75 ? COLOR.Gold : randomColor();return {size: 380 + size * 75,starDensity: 1,starLife: 600 + size * 100,starLifeVariation: 0.32,glitter: 'light',glitterColor: COLOR.Gold,color,crackle: true,pistil: Math.random() {const color = randomColor();return {horsetail: true,color,size: 250 + size * 38,starDensity: 0.85 + size * 0.1,starLife: 2500 + size * 300,glitter: 'medium',glitterColor: Math.random() < 0.5 ? whiteOrGold() : color};};function randomShellName() {return Math.random() options += `${opt}`);appNodes.shellType.innerHTML = options;// shell sizeoptions = '';['3"', '5"', '6"', '8"', '12"'].forEach((opt, i) => options += `${opt}`);appNodes.shellSize.innerHTML = options;// initial renderrenderApp(store.state);}function fitShellPositionInBoundsH(position) {const edge = 0.18;return (1 - edge * 2) * position + edge;}function fitShellPositionInBoundsV(position) {return position * 0.75;}function getRandomShellPositionH() {return fitShellPositionInBoundsH(Math.random());}function getRandomShellPositionV() {return fitShellPositionInBoundsV(Math.random());}function getRandomShellSize() {const baseSize = shellSizeSelector();const maxVariance = Math.min(2.5, baseSize);const variance = Math.random() * maxVariance;const size = baseSize - variance;const height = maxVariance === 0 ? Math.random() : 1 - (variance / maxVariance);const centerOffset = Math.random() * (1 - height * 0.65) * 0.5;const x = Math.random() {const offset = Math.random() * 0.08 - 0.04;const shell2 = new Shell(shellType(smallSize));shell2.launch(0.2 + offset, 0.1);}, leftDelay);setTimeout(() => {const offset = Math.random() * 0.08 - 0.04;const shell3 = new Shell(shellType(smallSize));shell3.launch(0.8 + offset, 0.1);}, rightDelay);return 4000;}function seqSmallBarrage() {seqSmallBarrage.lastCalled = Date.now();const barrageCount = IS_DESKTOP ? 11 : 5;const shellSize = Math.max(0, shellSizeSelector() - 2);const useCrysanthemum = Math.random() < 0.7;// (cos(x*5π+0.5π)+1)/2 is a custom wave bounded by 0 and 1 used to set varying launch heightsfunction launchShell(x) {const isRandom = shellNameSelector() === 'Random';let shellType = isRandom ? (useCrysanthemum ? crysanthemumShell : randomFastShell()) : shellTypes[shellNameSelector()];const shell = new Shell(shellType(shellSize));const height = (Math.cos(x * 5 * Math.PI + PI_HALF) + 1) / 2;shell.launch(x, height * 0.75);}let count = 0;let delay = 0;while (count {launchShell(0.5 + offset);launchShell(0.5 - offset);}, delay);count += 2;}delay += 200;}return 3400 + barrageCount * 120;}seqSmallBarrage.cooldown = 15000;seqSmallBarrage.lastCalled = Date.now();const sequences = [seqRandomShell,seqTwoRandom,seqTriple,seqSmallBarrage];let isFirstSeq = true;const finaleCount = 32;let currentFinaleCount = 0;function startSequence() {if (isFirstSeq) {isFirstSeq = false;const shell = new Shell(crysanthemumShell(shellSizeSelector()));shell.launch(0.5, 0.5);return 2400;}if (finaleSelector()) {seqRandomShell();if (currentFinaleCount < finaleCount) {currentFinaleCount++;return 170;}else {currentFinaleCount = 0;return 6000;}}const rand = Math.random();if (rand seqSmallBarrage.cooldown) {return seqSmallBarrage();}if (rand < 0.6) {return seqRandomShell();}else if (rand < 0.8) {return seqTwoRandom();}else if (rand < 1) {return seqTriple();}}let activePointerCount = 0;let isUpdatingSpeed = false;function handlePointerStart(event) {activePointerCount++;const btnSize = 44;if (event.y < btnSize) {if (event.x mainStage.width / 2 - btnSize / 2 && event.x mainStage.width - btnSize) {toggleMenu();return;}}if (!canInteract()) return;if (updateSpeedFromEvent(event)) {isUpdatingSpeed = true;}else if (event.onCanvas) {launchShellFromConfig(event);}}function handlePointerEnd(event) {activePointerCount--;isUpdatingSpeed = false;}function handlePointerMove(event) {if (!canInteract()) return;if (isUpdatingSpeed) {updateSpeedFromEvent(event);}}function handleKeydown(event) {// Pif (event.keyCode === 80) {togglePause();}// Oelse if (event.keyCode === 79) {toggleMenu();}// Escelse if (event.keyCode === 27) {toggleMenu(false);}}mainStage.addEventListener('pointerstart', handlePointerStart);mainStage.addEventListener('pointerend', handlePointerEnd);mainStage.addEventListener('pointermove', handlePointerMove);window.addEventListener('keydown', handleKeydown);// Try to go fullscreen upon a touchwindow.addEventListener('touchend', (event) => !IS_DESKTOP && requestFullscreen());function handleResize() {const w = window.innerWidth;const h = window.innerHeight;// Try to adopt screen size, heeding maximum sizes specifiedconst containerW = Math.min(w, MAX_WIDTH);// On small screens, use full device heightconst containerH = w stage.resize(containerW, containerH));}// Compute initial dimensionshandleResize();window.addEventListener('resize', handleResize);// Dynamic globalslet speedBarOpacity = 0;let autoLaunchTime = 0;function updateSpeedFromEvent(event) {if (isUpdatingSpeed || event.y >= mainStage.height - 44) {// On phones it's hard to hit the edge pixels in order to set speed at 0 or 1, so some padding is provided to make that easier.const edge = 16;const newSpeed = (event.x - edge) / (mainStage.width - edge * 2);simSpeed = Math.min(Math.max(newSpeed, 0), 1);// show speed bar after an updatespeedBarOpacity = 1;// If we updated the speed, return truereturn true;}// Return false if the speed wasn't updatedreturn false;}// Extracted function to keep `update()` optimizedfunction updateGlobals(timeStep, lag) {// Always try to fade out speed barif (!isUpdatingSpeed) {speedBarOpacity -= lag / 30; // half a secondif (speedBarOpacity < 0) {speedBarOpacity = 0;}}// auto launch shellsif (store.state.config.autoLaunch) {autoLaunchTime -= timeStep;if (autoLaunchTime {// StarsStar.active[color].forEach((star, i, stars) => {star.life -= timeStep;if (star.life <= 0) {stars.splice(i, 1);Star.returnInstance(star);} else {star.prevX = star.x;star.prevY = star.y;star.x += star.speedX * speed;star.y += star.speedY * speed;// Apply air drag if star isn't "heavy". The heavy property is used for the shell comets.if (!star.heavy) {star.speedX *= starDrag;star.speedY *= starDrag;}else {star.speedX *= starDragHeavy;star.speedY *= starDragHeavy;}star.speedY += gAcc;if (star.spinRadius) {star.spinAngle += star.spinSpeed * speed;star.x += Math.sin(star.spinAngle) * star.spinRadius * speed;star.y += Math.cos(star.spinAngle) * star.spinRadius * speed;}if (star.sparkFreq) {star.sparkTimer -= timeStep;while (star.sparkTimer {spark.life -= timeStep;if (spark.life {const stars = Star.active[color];trailsCtx.strokeStyle = color;trailsCtx.beginPath();stars.forEach(star => {trailsCtx.moveTo(star.x, star.y);trailsCtx.lineTo(star.prevX, star.prevY);mainCtx.moveTo(star.x, star.y);mainCtx.lineTo(star.x - star.speedX * 1.6, star.y - star.speedY * 1.6);});trailsCtx.stroke();});mainCtx.stroke();// Draw sparkstrailsCtx.lineWidth = Spark.drawWidth;trailsCtx.lineCap = 'butt';COLOR_CODES.forEach(color => {const sparks = Spark.active[color];trailsCtx.strokeStyle = color;trailsCtx.beginPath();sparks.forEach(spark => {trailsCtx.moveTo(spark.x, spark.y);trailsCtx.lineTo(spark.prevX, spark.prevY);});trailsCtx.stroke();});// Render speed bar if visibleif (speedBarOpacity) {const speedBarHeight = 6;mainCtx.globalAlpha = speedBarOpacity;mainCtx.fillStyle = COLOR.Blue;mainCtx.fillRect(0, height - speedBarHeight, width * simSpeed, speedBarHeight);mainCtx.globalAlpha = 1;}trailsCtx.resetTransform();mainCtx.resetTransform();}// Draw colored overlay based on combined brightness of stars (light up the sky!)// Note: this is applied to the canvas container's background-color, so it's behind the particlesconst currentSkyColor = { r: 0, g: 0, b: 0 };const targetSkyColor = { r: 0, g: 0, b: 0 };function colorSky(speed) {// The maximum r, g, or b value that will be used (255 would represent no maximum)const maxSkySaturation = 30;// How many stars are required in total to reach maximum sky brightnessconst maxStarCount = 500;let totalStarCount = 0;// Initialize sky as blacktargetSkyColor.r = 0;targetSkyColor.g = 0;targetSkyColor.b = 0;// Add each known color to sky, multiplied by particle count of that color. This will put RGB values wildly out of bounds, but we'll scale them back later.// Also add up total star count.COLOR_CODES.forEach(color => {const tuple = COLOR_TUPLES[color];const count = Star.active[color].length;totalStarCount += count;targetSkyColor.r += tuple.r * count;targetSkyColor.g += tuple.g * count;targetSkyColor.b += tuple.b * count;});// Clamp intensity at 1.0, and map to a custom non-linear curve. This allows few stars to perceivably light up the sky, while more stars continue to increase the brightness but at a lesser rate. This is more inline with humans' non-linear brightness perception.const intensity = Math.pow(Math.min(1, totalStarCount / maxStarCount), 0.3);// Figure out which color component has the highest value, so we can scale them without affecting the ratios.// Prevent 0 from being used, so we don't divide by zero in the next step.const maxColorComponent = Math.max(1, targetSkyColor.r, targetSkyColor.g, targetSkyColor.b);// Scale all color components to a max of `maxSkySaturation`, and apply intensity.targetSkyColor.r = targetSkyColor.r / maxColorComponent * maxSkySaturation * intensity;targetSkyColor.g = targetSkyColor.g / maxColorComponent * maxSkySaturation * intensity;targetSkyColor.b = targetSkyColor.b / maxColorComponent * maxSkySaturation * intensity;// Animate changes to color to smooth out transitions.const colorChange = 10;currentSkyColor.r += (targetSkyColor.r - currentSkyColor.r) / colorChange * speed;currentSkyColor.g += (targetSkyColor.g - currentSkyColor.g) / colorChange * speed;currentSkyColor.b += (targetSkyColor.b - currentSkyColor.b) / colorChange * speed;appNodes.canvasContainer.style.backgroundColor = `rgb(${currentSkyColor.r | 0}, ${currentSkyColor.g | 0}, ${currentSkyColor.b | 0})`;}mainStage.addEventListener('ticker', update);// Helper used to semi-randomly spread particles over an arc// Values are flexible - `start` and `arcLength` can be negative, and `randomness` is simply a multiplier for random addition.function createParticleArc(start, arcLength, count, randomness, particleFactory) {const angleDelta = arcLength / count;// Sometimes there is an extra particle at the end, too close to the start. Subtracting half the angleDelta ensures that is skipped.// Would be nice to fix this a better way.const end = start + arcLength - (angleDelta * 0.5);if (end > start) {// Optimization: `angle=angle+angleDelta` vs. angle+=angleDelta// V8 deoptimises with let compound assignmentfor (let angle = start; angle end; angle = angle + angleDelta) {particleFactory(angle + Math.random() * angleDelta * randomness);}}}// Various star effects.// These are designed to be attached to a star's `onDeath` event.// Crossette breaks star into four same-color pieces which branch in a cross-like shape.function crossetteEffect(star) {const startAngle = Math.random() * PI_HALF;createParticleArc(startAngle, PI_2, 4, 0.5, (angle) => {Star.add(star.x,star.y,star.color,angle,Math.random() * 0.6 + 0.75,600);});}// Flower is like a mini shellfunction floralEffect(star) {const startAngle = Math.random() * PI_HALF;createParticleArc(startAngle, PI_2, 24, 1, (angle) => {Star.add(star.x,star.y,star.color,angle,// apply near cubic falloff to speed (places more particles towards outside)Math.pow(Math.random(), 0.45) * 2.4,1000 + Math.random() * 300,star.speedX,star.speedY);});// Queue burst flash renderBurstFlash.add(star.x, star.y, 24);}// Floral burst with willow starsfunction fallingLeavesEffect(star) {const startAngle = Math.random() * PI_HALF;createParticleArc(startAngle, PI_2, 12, 1, (angle) => {const newStar = Star.add(star.x,star.y,INVISIBLE,angle,// apply near cubic falloff to speed (places more particles towards outside)Math.pow(Math.random(), 0.45) * 2.4,2400 + Math.random() * 600,star.speedX,star.speedY);newStar.sparkColor = COLOR.Gold;newStar.sparkFreq = 72;newStar.sparkSpeed = 0.28;newStar.sparkLife = 750;newStar.sparkLifeVariation = 3.2;});// Queue burst flash renderBurstFlash.add(star.x, star.y, 24);}// Crackle pops into a small cloud of golden sparks.function crackleEffect(star) {createParticleArc(0, PI_2, 10, 1.8, (angle) => {Spark.add(star.x,star.y,COLOR.Gold,angle,// apply near cubic falloff to speed (places more particles towards outside)Math.pow(Math.random(), 0.45) * 2.4,300 + Math.random() * 200);});}/** * Shell can be constructed with options: * * size:Size of the burst. * starCount: Number of stars to create. This is optional, and will be set to a reasonable quantity for size if omitted. * starLife: * starLifeVariation: * color: * glitterColor: * glitter: One of: 'light', 'medium', 'heavy', 'streamer', 'willow' * pistil: * pistilColor: * streamers: * crossette: * floral: * crackle: */class Shell {constructor(options) {Object.assign(this, options);this.starLifeVariation = options.starLifeVariation || 0.125;this.color = options.color || randomColor();this.glitterColor = options.glitterColor || this.color;// Set default starCount if needed, will be based on shell size and scale exponentially, like a sphere's surface area.if (!this.starCount) {const density = options.starDensity || 1;const scaledSize = this.size / 50 * density;this.starCount = scaledSize * scaledSize;}}launch(position, launchHeight) {const { width, height } = mainStage;// Distance from sides of screen to keep shells.const hpad = 60;// Distance from top of screen to keep shell bursts.const vpad = 50;// Minimum burst height, as a percentage of stage heightconst minHeightPercent = 0.45;// Minimum burst height in pxconst minHeight = height - height * minHeightPercent;const launchX = position * (width - hpad * 2) + hpad;const launchY = height;const burstY = minHeight - (launchHeight * (minHeight - vpad));const launchDistance = launchY - burstY;// Using a custom power curve to approximate Vi needed to reach launchDistance under gravity and air drag.// Magic numbers came from testing.const launchVelocity = Math.pow(launchDistance * 0.04, 0.64);const comet = this.comet = Star.add(launchX,launchY,typeof this.color === 'string' && this.color !== 'random' ? this.color : COLOR.White,Math.PI,launchVelocity * (this.horsetail ? 1.2 : 1),// Hang time is derived linearly from Vi; exact number came from testinglaunchVelocity * (this.horsetail ? 100 : 400));// making comet "heavy" limits air dragcomet.heavy = true;// comet spark trailcomet.spinRadius = 0.78;comet.sparkFreq = 16;if (this.glitter === 'willow' || this.fallingLeaves) {comet.sparkFreq = 10;comet.sparkSpeed = 0.5;comet.sparkLife = 500;comet.sparkLifeVariation = 3;}if (this.color === INVISIBLE) {comet.sparkColor = COLOR.Gold;}comet.onDeath = comet => this.burst(comet.x, comet.y);// comet.onDeath = () => this.burst(launchX, burstY);}burst(x, y) {// Set burst speed so overall burst grows to set size. This specific formula was derived from testing, and is affected by simulated air drag.const speed = this.size / 96;let color, onDeath, sparkFreq, sparkSpeed, sparkLife;let sparkLifeVariation = 0.25;if (this.crossette) onDeath = crossetteEffect;if (this.floral) onDeath = floralEffect;if (this.crackle) onDeath = crackleEffect;if (this.fallingLeaves) onDeath = fallingLeavesEffect;if (this.glitter === 'light') {sparkFreq = 200;sparkSpeed = 0.25;sparkLife = 600;}else if (this.glitter === 'medium') {sparkFreq = 100;sparkSpeed = 0.36;sparkLife = 1400;}else if (this.glitter === 'heavy') {sparkFreq = 42;sparkSpeed = 0.62;sparkLife = 2800;}else if (this.glitter === 'streamer') {sparkFreq = 20;sparkSpeed = 0.75;sparkLife = 800;}else if (this.glitter === 'willow') {sparkFreq = 72;sparkSpeed = 0.28;sparkLife = 1000;sparkLifeVariation = 3.4;}const starFactory = angle => {const star = Star.add(x,y,color || randomColor(),angle,// apply near cubic falloff to speed (places more particles towards outside)Math.pow(Math.random(), 0.45) * speed,// add minor variation to star lifethis.starLife + Math.random() * this.starLife * this.starLifeVariation,this.horsetail && this.comet && this.comet.speedX,this.horsetail && this.comet && this.comet.speedY);star.onDeath = onDeath;if (this.glitter) {star.sparkFreq = sparkFreq;star.sparkSpeed = sparkSpeed;star.sparkLife = sparkLife;star.sparkLifeVariation = sparkLifeVariation;star.sparkColor = this.glitterColor;star.sparkTimer = Math.random() * star.sparkFreq;}};if (typeof this.color === 'string') {if (this.color === 'random') {color = null; // falsey value creates random color in starFactory} else {color = this.color;}// Rings have positional randomness, but are rotated randomlyif (this.ring) {const ringStartAngle = Math.random() * Math.PI;const ringSquash = Math.pow(Math.random(), 0.45) * 0.992 + 0.008;createParticleArc(0, PI_2, this.starCount, 0, angle => {// Create a ring, squashed horizontallyconst initSpeedX = Math.sin(angle) * speed * ringSquash;const initSpeedY = Math.cos(angle) * speed;// Rotate ringconst newSpeed = MyMath.pointDist(0, 0, initSpeedX, initSpeedY);const newAngle = MyMath.pointAngle(0, 0, initSpeedX, initSpeedY) + ringStartAngle;const star = Star.add(x,y,color,newAngle,// apply near cubic falloff to speed (places more particles towards outside)newSpeed,//speed,// add minor variation to star lifethis.starLife + Math.random() * this.starLife * this.starLifeVariation);if (this.glitter) {star.sparkFreq = sparkFreq;star.sparkSpeed = sparkSpeed;star.sparkLife = sparkLife;star.sparkLifeVariation = sparkLifeVariation;star.sparkColor = this.glitterColor;star.sparkTimer = Math.random() * star.sparkFreq;}});}// "Normal burstelse {createParticleArc(0, PI_2, this.starCount, 1, starFactory);}}else if (Array.isArray(this.color)) {let start, start2, arc;if (Math.random() {collection[color] = [];});return collection;}const Star = {// Visual propertiesdrawWidth: 3,airDrag: 0.98,airDragHeavy: 0.992,// Star particles will be keyed by coloractive: createParticleCollection(),_pool: [],_new() {return {};},add(x, y, color, angle, speed, life, speedOffX, speedOffY) {const instance = this._pool.pop() || this._new();instance.heavy = false;instance.x = x;instance.y = y;instance.prevX = x;instance.prevY = y;instance.color = color;instance.speedX = Math.sin(angle) * speed + (speedOffX || 0);instance.speedY = Math.cos(angle) * speed + (speedOffY || 0);instance.life = life;instance.spinAngle = Math.random() * PI_2;instance.spinSpeed = 0.8;instance.spinRadius = 0;instance.sparkFreq = 0; // ms between spark emissionsinstance.sparkSpeed = 1;instance.sparkTimer = 0;instance.sparkColor = color;instance.sparkLife = 750;instance.sparkLifeVariation = 0.25;this.active[color].push(instance);return instance;},// Public method for cleaning up and returning an instance back to the pool.returnInstance(instance) {// Call onDeath handler if available (and pass it current star instance)instance.onDeath && instance.onDeath(instance);// Clean upinstance.onDeath = null;// Add back to the pool.this._pool.push(instance);}};const Spark = {// Visual propertiesdrawWidth: 0.75,airDrag: 0.9,// Star particles will be keyed by coloractive: createParticleCollection(),_pool: [],_new() {return {};},add(x, y, color, angle, speed, life) {const instance = this._pool.pop() || this._new();instance.x = x;instance.y = y;instance.prevX = x;instance.prevY = y;instance.color = color;instance.speedX = Math.sin(angle) * speed;instance.speedY = Math.cos(angle) * speed;instance.life = life;this.active[color].push(instance);return instance;},// Public method for cleaning up and returning an instance back to the pool.returnInstance(instance) {// Add back to the pool.this._pool.push(instance);}};init();二、代码原理
这段代码的实现原理主要是通过 HTML、CSS 和外部资源（图标、字体和样式表）来构建一个具有烟花秀效果的网页。
首先，通过标签设置文档的元数据，如字符编码、视口大小等。然后，通过标签引入外部资源，包括图标、字体和样式表。
在标签中，定义了一系列的 CSS 样式规则。这些样式规则用于设置页面元素的位置、尺寸、颜色、字体等样式属性。例如，设置容器的高度为100%，设置背景颜色为黑色，设置文字的颜色和字体等。
在样式规则中，使用了类选择器（以.开头）和id选择器（以#开头）来选择特定的元素，并对它们应用相应的样式。例如，通过.container选择器选择了类名为.container的元素，并设置其为居中对齐。
此外，还使用了媒体查询（@media）来根据不同的屏幕宽度设置不同的样式。例如，在宽度大于800px时，显示菜单栏并设置透明度为1；在小于800px时，隐藏菜单栏。
整个页面的布局和样式通过HTML和CSS实现，通过引入外部资源来美化页面。最终效果是一个具有烟花秀效果的网页，用户可以在此网页上观看跨年烟花秀。
鉴于该代码较长，此处只对一小部分核心代码进行解释说明，具体如下所示：
：声明文档类型为 HTML。：开始 HTML 标签，并指定页面语言为英语。：头部标签，包含了关于文档的元数据。：设置字符编码为 UTF-8。跨年烟花秀 - 一系列
标签：设置视口、苹果设备支持、主题色等元信息。 - 一系列
标签：引入图标、字体和样式表等外部资源。 ：内部样式表，定义页面元素的样式。- CSS样式规则：包括元素的位置、尺寸、颜色、字体等样式设置。
* {...}：通配符样式，设置所有元素的默认样式。.container {...}：定义类名为.container的容器样式。#loading-init {...}：定义id为loading-init的元素样式。#stage-container {...}：定义id为stage-container的元素样式。#canvas-container {...}：定义id为canvas-container的元素样式。#controls {...}：定义id为controls的元素样式。- 媒体查询
@media (min-width: 800px)：针对不同屏幕宽度设置不同的样式。 #menu {...}：定义id为menu的元素样式。#menu__header {...}：定义id为menu__header的元素样式。#menu form {...}：定义form元素的样式。#menu .form-option {...}：定义类名为.form-option的表单选项样式。#menu .form-option label {...}：定义表单选项中的标签样式。#menu .form-option--select {...}：定义下拉选择框的样式。#menu .form-option--checkbox {...}：定义复选框的样式。- 媒体查询
@media (max-width: 800px)：针对小屏幕设备设置不同的样式。 #close-menu-btn {...}：定义关闭菜单按钮样式。.btn {...}：定义按钮样式。.btn svg {...}：定义按钮内的 SVG 图标样式。
三、运行效果
