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！
'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 localStorage
load() {
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(服务器托管网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 state
const 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 nodes
Object.keys(appNodes).forEach(key => {
appNodes[key] = document.querySelector(appNodes[key]);
});
// Remove loading state
document.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 derivations
const 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 randomly
if (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 gold
const 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 += `${opt}`);
appNodes.shellType.innerHTML = options;
// shell size
options = '';
['3"', '5"', '6"', '8"', '12"'].forEach((opt, i) => options += `${opt}`);
appNodes.shellSize.innerHTML = options;
// initial render
renderApp(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*5+0.5)+1)/2 is a custom wave bounded by 0 and 1 used to set varying launch heights
function 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) {
// P
if (event.keyCode === 80) {
togglePause();
}
// O
else if (event.keyCode === 79) {
toggleMenu();
}
// Esc
else 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 touch
window.addEventListener('touchend', (event) => !IS_DESKTOP && requestFullscreen());
function handleResize() {
const w = window.innerWidth;
const h = window.innerHeight;
// Try to adopt screen size, heeding maximum sizes specified
const containerW = Math.min(w, MAX_WIDTH);
// On small screens, use full device height
const containerH = w stage.resize(containerW, containerH));
}
// Compute initial dimensions
handleResize();
window.addEventListener('resize', handleResize);
// Dynamic globals
let 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 update
speedBarOpacity = 1;
// If we updated the speed, return true
return true;
}
// Return false if the speed wasn't updated
return false;
}
// Extracted function to keep `update()` optimized
function updateGlobals(timeStep, lag) {
// Always try to fade out speed bar
if (!isUpdatingSpeed) {
speedBarOpacity -= lag / 30; // half a second
if (speedBarOpacity < 0) {
speedBarOpacity = 0;
}
}
// auto launch shells
if (store.state.config.autoLaunch) {
autoLaunchTime -= timeStep;
if (autoLaunchTime {
// Stars
Star.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 sparks
trailsCtx.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 visible
if (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 particles
const 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 brightness
const maxStarCount = 500;
let totalStarCount = 0;
// Initialize sky as black
targetSkyColor.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 assignment
for (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 shell
funct服务器托管网ion 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 render
BurstFlash.add(star.x, star.y, 24);
}
// Floral burst with willow stars
function 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 render
BurstFlash.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 height
const minHeightPercent = 0.45;
// Minimum burst height in px
const 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 testing
launchVelocity * (this.horsetail ? 100 : 400)
);
// making comet "heavy" limits air drag
comet.heavy = true;
// comet spark trail
comet.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 life
this.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 randomly
if (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 horizontally
const initSpeedX = Math.sin(angle) * speed * ringSquash;
const initSpeedY = Math.cos(angle) * speed;
// Rotate ring
const 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 life
this.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 burst
else {
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 properties
drawWidth: 3,
airDrag: 0.98,
airDragHeavy: 0.992,
// Star particles will be keyed by color
active: 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 emissions
instance.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 up
instance.onDeath = null;
// Add back to the pool.
this._pool.push(instance);
}
};
const Spark = {
// Visual properties
drawWidth: 0.75,
airDrag: 0.9,
// Star particles will be keyed by color
active: 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
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OD统一考试（C卷） 分值： 100分 题解： Java / Python / C++ 题目描述 在一个大型体育场内举办了一场大型活动，由于疫情防控的需要，要求每位观众的必须间隔至少一个空位才允许落座。 现在给出一排观众座位分布图，座位中存在已落座的观众，请计…
