本篇內(nèi)容介紹了“如何使用HTML5 Canvas制作水波紋效果”的有關(guān)知識，在實際案例的操作過程中，不少人都會遇到這樣的困境，接下來就讓小編帶領(lǐng)大家學(xué)習(xí)一下如何處理這些情況吧！希望大家仔細(xì)閱讀，能夠?qū)W有所成！

創(chuàng)新互聯(lián)公司主要從事網(wǎng)頁設(shè)計、PC網(wǎng)站建設(shè)（電腦版網(wǎng)站建設(shè)）、wap網(wǎng)站建設(shè)（手機版網(wǎng)站建設(shè)）、響應(yīng)式網(wǎng)站建設(shè)、程序開發(fā)、網(wǎng)站優(yōu)化、微網(wǎng)站、重慶小程序開發(fā)公司等，憑借多年來在互聯(lián)網(wǎng)的打拼，我們在互聯(lián)網(wǎng)網(wǎng)站建設(shè)行業(yè)積累了豐富的成都網(wǎng)站設(shè)計、成都做網(wǎng)站、網(wǎng)站設(shè)計、網(wǎng)絡(luò)營銷經(jīng)驗，集策劃、開發(fā)、設(shè)計、營銷、管理等多方位專業(yè)化運作于一體。

今天，我們繼續(xù)分享 JavaScript 實現(xiàn)的效果例子，這篇文章會介紹使用 JavaScript 實現(xiàn)水波紋效果。水波效果以圖片為背景，點擊圖片任意位置都會觸發(fā)。有時候，我們使用普通的 Javascript 就可以創(chuàng)建一個很有趣的解決功能。
 

源碼下載

Step 1. HTML

和以前一樣，首先是 HTML 代碼：

代碼如下:

Water drops effect

HTML5 compliant browser required

Step 2. CSS

這是用到的 CSS 代碼：

代碼如下:

body{background:#eee;margin:0;padding:0}
.example{background:#FFF;width:600px;border:1px #000 solid;margin:20px auto;padding:15px;-moz-border-radius: 3px;-webkit-border-radius: 3px}
#water {
width:500px;
height:400px;
display: block;
margin:0px auto;
cursor:pointer;
}
#switcher {
text-align:center;
overflow:hidden;
margin:15px;
}
#switcher img {
width:160px;
height:120px;
}

Step 3. JS

下面是主要的 JavaScript 代碼：

代碼如下:

function drop(x, y, damping, shading, refraction, ctx, screenWidth, screenHeight){
this.x = x;
this.y = y;
this.shading = shading;
this.refraction = refraction;
this.bufferSize = this.x * this.y;
this.damping = damping;
this.background = ctx.getImageData(0, 0, screenWidth, screenHeight).data;
this.imageData = ctx.getImageData(0, 0, screenWidth, screenHeight);
this.buffer1 = [];
this.buffer2 = [];
for (var i = 0; i < this.bufferSize; i++){
this.buffer1.push(0);
this.buffer2.push(0);
}
this.update = function(){
for (var i = this.x + 1, x = 1; i < this.bufferSize - this.x; i++, x++){
if ((x < this.x)){
this.buffer2[i] = ((this.buffer1[i - 1] + this.buffer1[i + 1] + this.buffer1[i - this.x] + this.buffer1[i + this.x]) / 2) - this.buffer2[i];
this.buffer2[i] *= this.damping;
} else x = 0;
}
var temp = this.buffer1;
this.buffer1 = this.buffer2;
this.buffer2 = temp;
}
this.draw = function(ctx){
var imageDataArray = this.imageData.data;
for (var i = this.x + 1, index = (this.x + 1) * 4; i < this.bufferSize - (1 + this.x); i++, index += 4){
var xOffset = ~~(this.buffer1[i - 1] - this.buffer1[i + 1]);
var yOffset = ~~(this.buffer1[i - this.x] - this.buffer1[i + this.x]);
var shade = xOffset * this.shading;
var texture = index + (xOffset * this.refraction + yOffset * this.refraction * this.x) * 4;
imageDataArray[index] = this.background[texture] + shade;
imageDataArray[index + 1] = this.background[texture + 1] + shade;
imageDataArray[index + 2] = 50 + this.background[texture + 2] + shade;
}
ctx.putImageData(this.imageData, 0, 0);
}
}
var fps = 0;
var watereff = {
// variables
timeStep : 20,
refractions : 2,
shading : 3,
damping : 0.99,
screenWidth : 500,
screenHeight : 400,
pond : null,
textureImg : null,
interval : null,
backgroundURL : 'data_images/underwater1.jpg',
// initialization
init : function() {
var canvas = document.getElementById('water');
if (canvas.getContext){
// fps countrt
fps = 0;
setInterval(function() {
document.getElementById('fps').innerHTML = fps / 2 + ' FPS';
fps = 0;
}, 2000);
canvas.onmousedown = function(e) {
var mouse = watereff.getMousePosition(e).sub(new vector2d(canvas.offsetLeft, canvas.offsetTop));
watereff.pond.buffer1[mouse.y * watereff.pond.x + mouse.x ] += 200;
}
canvas.onmouseup = function(e) {
canvas.onmousemove = null;
}
canvas.width = this.screenWidth;
canvas.height = this.screenHeight;
this.textureImg = new Image(256, 256);
this.textureImg.src = this.backgroundURL;
canvas.getContext('2d').drawImage(this.textureImg, 0, 0);
this.pond = new drop(
this.screenWidth,
this.screenHeight,
this.damping,
this.shading,
this.refractions,
canvas.getContext('2d'),
this.screenWidth, this.screenHeight
);
if (this.interval != null){
clearInterval(this.interval);
}
this.interval = setInterval(watereff.run, this.timeStep);
}
},
// change image func
changePicture : function(url){
this.backgroundURL = url;
this.init();
},
// get mouse position func
getMousePosition : function(e){
if (!e){
var e = window.event;
}
if (e.pageX || e.pageY){
return new vector2d(e.pageX, e.pageY);
} else if (e.clientX || e.clientY){
return new vector2d(e.clientX, e.clientY);
}
},
// loop drawing
run : function(){
var ctx = document.getElementById('water').getContext('2d');
watereff.pond.update();
watereff.pond.draw(ctx);
fps++;
}
}
window.onload = function(){
watereff.init();
}

正如你所看到的，這里使用 Vector2D 函數(shù)，這個函數(shù)在 vector2d.js 里提供了。另一個很難的方法是使用純數(shù)學(xué)實現(xiàn)，感興趣的可以自己實驗一下。

“如何使用HTML5 Canvas制作水波紋效果”的內(nèi)容就介紹到這里了，感謝大家的閱讀。如果想了解更多行業(yè)相關(guān)的知識可以關(guān)注創(chuàng)新互聯(lián)網(wǎng)站，小編將為大家輸出更多高質(zhì)量的實用文章！