How to use HTML5 Canvas to create water ripple effects

Today, we continue to share examples of the effects of JavaScript implementations, and this article describes the use of JavaScript for water ripple effects. The water wave effect takes the picture as the background, the click image anywhere will trigger. Sometimes, we can create a very interesting solution using normal Javascript .

Online Demo Source Download

Step 1. Html

As before, the first is the HTML code:

<! DOCTYPE html>Step 2. Css
Here is the CSS code used:
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
Here's the main JavaScript code:
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-t                His.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] = + 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:funct        Ion () {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.offsetl                EFT, 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.S            Creenwidth, 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 ();}
As you can see, the VECTOR2D function is used here, and this function is provided in the vector2d.js. Another difficult way is to use pure mathematics to achieve, interested can experiment with their own.
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How to use HTML5 Canvas to create water ripple effects