canvas怎样做出黑色背景带特效碎屑烟花
导读：收集整理的这篇文章主要介绍了canvas怎样做出黑色背景带特效碎屑烟花，觉得挺不错的，现在分享给大家，也给大家做个参考。这次给大家带来canvas怎样做出黑色背景带特效碎屑烟花，canvas做出黑色背景带特效碎屑烟花的注意事项有哪些，下面就...
收集整理的这篇文章主要介绍了canvas怎样做出黑色背景带特效碎屑烟花，觉得挺不错的，现在分享给大家，也给大家做个参考。这次给大家带来canvas怎样做出黑色背景带特效碎屑烟花，canvas做出黑色背景带特效碎屑烟花的注意事项有哪些，下面就是实战案例，一起来看一下。canvas id="cas" style="background-color:rgba(0,5,24,1)" width="1235" height="680">
浏览器不支持canvas/canvas>
div class="cITy">
img src="city.png" alt="">
/div>
img src="moon.png" alt="" id="moon" style="visibility: hidden;
">
div style="display:none">
div class="Shape">
新年快乐/div>
div class="shaPE">
阖家欢乐/div>
div class="shape">
万事如意/div>
div class="shape">
心想事成/div>
/div>
css
body {
margin: 0;
padding: 0;
overflow: hidden;
}
.city {
width: 100%;
position: fixed;
bottom: 0px;
z-index: 100;
}
.city img {
width: 100%;
}
js
VAR canvas = document.getElementById("cas");
var ocas = document.createElement("canvas");
var octx = ocas.getContext("2d");
var ctx = canvas.getContext("2d");
ocas.width = canvas.width = window.innerWidth;
ocas.height = canvas.height = window.innerHeight;
var Bigbooms = [];
window.onload = function () {
initAniMATE()}
function initAnimate() {
drawBg();
lastTime = new Date();
animate();
}
var lastTime;
function animate() {
ctx.save();
ctx.fillStyle = "rgba(0,5,24,0.1)";
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.reStore();
var newTime = new Date();
if (newTime - lastTime >
500 + (window.innerHeight - 767) / 2) {
var random = Math.random() * 100 >
2 ? true : false;
var x = getRandom(canvas.width / 5, canvas.width * 4 / 5);
var y = getRandom(50, 200);
if (random) {
var bigboom = new Boom(getRandom(canvas.width / 3, canvas.width * 2 / 3), 2, "#FFF", {
x: x, y: y }
);
bigbooms.push(bigboom) }
else {
var bigboom = new Boom(getRandom(canvas.width / 3, canvas.width * 2 / 3), 2, "#FFF", {
x: canvas.width / 2, y: 200 }
, document.querySelectorAll(".shape")[parseInt(getRandom(0, document.querySelectorAll( ".shape").length))]);
bigbooms.push(bigboom) }
lastTime = newTime;
}
stars.foreach(function () {
this.paint();
}
) drawMoon();
bigbooms.foreach(function (index) {
var that = this;
if (!this.dead) {
this._move();
this._drawLight();
}
else {
this.booms.foreach(function (index) {
if (!this.dead) {
this.moveTo(index);
}
else if (index === that.booms.length - 1) {
bigbooms[bigbooms.indexOf(that)] = null;
}
}
) }
}
);
raf(animate);
}
function drawMoon() {
var moon = document.getElementById("moon");
var centerX = canvas.width - 200, centerY = 100, width = 80;
if (moon.complete) {
ctx.drawImage(moon, centerX, centerY, width, width) }
else {
moon.onload = function () {
ctx.drawImage(moon, centerX, centerY, width, width) }
}
var index = 0;
for (var i = 0;
i 10;
i++) {
ctx.save();
ctx.beginPath();
ctx.arc(centerX + width / 2, centerY + width / 2, width / 2 + index, 0, 2 * Math.PI);
ctx.fillStyle = "rgba(240,219,120,0.005)";
index += 2;
ctx.fill();
ctx.restore();
}
}
Array.PRototype.foreach = function (callback) {
for (var i = 0;
i this.length;
i++) {
if (this[i] !== null) callback.apply(this[i], [i]) }
}
var raf = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function (callback) {
window.setTimeout(callback, 1000 / 60);
}
;
canvas.onclick = function () {
var x = event.clientX;
var y = event.clientY;
var bigboom = new Boom(getRandom(canvas.width / 3, canvas.width * 2 / 3), 2, "#FFF", {
x: x, y: y }
);
bigbooms.push(bigboom)}
var Boom = function (x, r, c, boomArea, shape) {
this.booms = [];
this.x = x;
this.y = (canvas.height + r);
this.r = r;
this.c = c;
this.shape = shape || false;
this.boomArea = boomArea;
this.theta = 0;
this.dead = false;
this.ba = parseInt(getRandom(80, 200));
}
Boom.prototype = {
_paint: function () {
ctx.save();
ctx.beginPath();
ctx.arc(this.x, this.y, this.r, 0, 2 * Math.PI);
ctx.fillStyle = this.c;
ctx.fill();
ctx.restore();
}
, _move: function () {
var dx = this.boomArea.x - this.x, dy = this.boomArea.y - this.y;
this.x = this.x + dx * 0.01;
this.y = this.y + dy * 0.01;
if (Math.abs(dx) = this.ba &
&
Math.abs(dy) = this.ba) {
if (this.shape) {
this._shapBoom();
}
else this._boom();
this.dead = true;
}
else {
this._paint();
}
}
, _drawLight: function () {
ctx.save();
ctx.fillStyle = "rgba(255,228,150,0.3)";
ctx.beginPath();
ctx.arc(this.x, this.y, this.r + 3 * Math.random() + 1, 0, 2 * Math.PI);
ctx.fill();
ctx.restore();
}
, _boom: function () {
var fragNum = getRandom(30, 200);
var style = getRandom(0, 10) >
= 5 ? 1 : 2;
var color;
if (style === 1) {
color = {
a: parseInt(getRandom(128, 255)), b: parseInt(getRandom(128, 255)), c: parseInt(getRandom(128, 255)) }
}
var fanwei = parseInt(getRandom(300, 400));
for (var i = 0;
i fragNum;
i++) {
if (style === 2) {
color = {
a: parseInt(getRandom(128, 255)), b: parseInt(getRandom(128, 255)), c: parseInt(getRandom(128, 255)) }
}
var a = getRandom(-Math.PI, Math.PI);
var x = getRandom(0, fanwei) * Math.cos(a) + this.x;
var y = getRandom(0, fanwei) * Math.sin(a) + this.y;
var radius = getRandom(0, 2) var frag = new Frag(this.x, this.y, radius, color, x, y);
this.booms.push(frag);
}
}
, _shapBoom: function () {
var that = this;
putValue(ocas, octx, this.shape, 5, function (dots) {
var dx = canvas.width / 2 - that.x;
var dy = canvas.height / 2 - that.y;
for (var i = 0;
i dots.length;
i++) {
color = {
a: dots[i].a, b: dots[i].b, c: dots[i].c }
var x = dots[i].x;
var y = dots[i].y;
var radius = 1;
var frag = new Frag(that.x, that.y, radius, color, x - dx, y - dy);
that.booms.push(frag);
}
}
) }
}
function putValue(canvas, context, ele, dr, callback) {
context.clearRect(0, 0, canvas.width, canvas.height);
var img = new Image();
if (ele.innerHTML.indexOf("img") >
= 0) {
img.src = ele.getelementsbytagname("img")[0].src;
imgload(img, function () {
context.drawImage(img, canvas.width / 2 - img.width / 2, canvas.height / 2 - img.width / 2);
dots = getimgData(canvas, context, dr);
callback(dots);
}
) }
else {
var text = ele.innerHTML;
context.save();
var fontSize = 200;
context.font = fontSize + "px 宋体 bold";
context.textAlign = "center";
context.textBaseline = "middle";
context.fillStyle = "rgba(" + parseInt(getRandom(128, 255)) + "," + parseInt(getRandom(128, 255)) + "," + parseInt(getRandom(128, 255)) + " , 1)";
context.fillText(text, canvas.width / 2, canvas.height / 2);
context.restore();
dots = getimgData(canvas, context, dr);
callback(dots);
}
}
function imgload(img, callback) {
if (img.COMplete) {
callback.call(img);
}
else {
img.onload = function () {
callback.call(this);
}
}
}
function getimgData(canvas, context, dr) {
var imgData = context.getImageData(0, 0, canvas.width, canvas.height);
context.clearRect(0, 0, canvas.width, canvas.height);
var dots = [];
for (var x = 0;
x imgData.width;
x += dr) {
for (var y = 0;
y imgData.height;
y += dr) {
var i = (y * imgData.width + x) * 4;
if (imgData.data[i + 3] >
128) {
var dot = {
x: x, y: y, a: imgData.data[i], b: imgData.data[i + 1], c: imgData.data[i + 2] }
;
dots.push(dot);
}
}
}
return dots;
}
function getRandom(a, b) {
return Math.random() * (b - a) + a;
}
var maxRadius = 1, stars = [];
function drawBg() {
for (var i = 0;
i 100;
i++) {
var r = Math.random() * maxRadius;
var x = Math.random() * canvas.width;
var y = Math.random() * 2 * canvas.height - canvas.height;
var star = new Star(x, y, r);
stars.push(star);
star.paint() }
}
var Star = function (x, y, r) {
this.x = x;
this.y = y;
this.r = r;
}
Star.prototype = {
paint: function () {
ctx.save();
ctx.beginPath();
ctx.arc(this.x, this.y, this.r, 0, 2 * Math.PI);
ctx.fillStyle = "rgba(255,255,255," + this.r + ")";
ctx.fill();
ctx.restore();
}
}
var focallength = 250;
var Frag = function (centerX, centerY, radius, color, tx, ty) {
this.tx = tx;
this.ty = ty;
this.x = centerX;
this.y = centerY;
this.dead = false;
this.centerX = centerX;
this.centerY = centerY;
this.radius = radius;
this.color = color;
}
Frag.prototype = {
paint: function () {
ctx.save();
ctx.beginPath();
ctx.arc(this.x, this.y, this.radius, 0, 2 * Math.PI);
ctx.fillStyle = "rgba(" + this.color.a + "," + this.color.b + "," + this.color.c + ",1)";
ctx.fill() ctx.restore();
}
, moveTo: function (index) {
this.ty = this.ty + 0.3;
var dx = this.tx - this.x, dy = this.ty - this.y;
this.x = Math.abs(dx) 0.1 ? this.tx : (this.x + dx * 0.1);
this.y = Math.abs(dy) 0.1 ? this.ty : (this.y + dy * 0.1);
if (dx === 0 &
&
Math.abs(dy) = 80) {
this.dead = true;
}
this.paint();
}
}
相信看了本文案例你已经掌握了方法，更多精彩请关注其它相关文章！
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以上就是canvas怎样做出黑色背景带特效碎屑烟花的详细内容，更多请关注其它相关文章！
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