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);
