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| <script> | | <canvas id="canvas" height="142px" width="673px"></canvas> |
| class FogParticle {
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| constructor(ctx, canvasWidth, canvasHeight) {
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| this.ctx = ctx
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| this.canvasWidth = canvasWidth
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| this.canvasHeight = canvasHeight
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| this.x = 0
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| this.y = 0
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| }
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| setPosition(x, y) {
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| this.x = x
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| this.y = y
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| }
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| setVelocity(x, y) {
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| this.xVelocity = x
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| this.yVelocity = y
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| }
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| setImage(image) {
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| this.image = image
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| }
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| render() {
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| if (!this.image) return
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| this.ctx.drawImage(
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| this.image,
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| this.x - this.image.width / 2,
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| this.y - this.image.height / 2,
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| 400,
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| 400
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| )
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| this.x += this.xVelocity
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| this.y += this.yVelocity
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| // Check if has crossed the right edge
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| if (this.x >= this.canvasWidth) {
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| this.xVelocity = -this.xVelocity
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| this.x = this.canvasWidth
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| }
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| // Check if has crossed the left edge
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| else if (this.x <= 0) {
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| this.xVelocity = -this.xVelocity
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| this.x = 0
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| }
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| // Check if has crossed the bottom edge
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| if (this.y >= this.canvasHeight) {
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| this.yVelocity = -this.yVelocity
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| this.y = this.canvasHeight
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| }
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| // Check if has crossed the top edge
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| else if (this.y <= 0) {
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| this.yVelocity = -this.yVelocity
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| this.y = 0
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| }
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| }
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| }
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| class Fog {
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| constructor({ selector, density = 50, velocity = 2, particle, bgi } = {}) {
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| const canvas = document.querySelector(selector)
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| const bcr = canvas.parentElement.getBoundingClientRect()
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| this.ctx = canvas.getContext('2d')
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| this.canvasWidth = canvas.width = bcr.width
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| this.canvasHeight = canvas.height = bcr.height
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| this.particleCount = density
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| this.maxVelocity = velocity
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| this.particle = particle
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| this.bgi = bgi
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| this._createParticles()
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| this._setImage()
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| if (!this.bgi) return
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| const img = new Image()
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| img.onload = () => {
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| const size = coverImg(img, this.canvasWidth, this.canvasHeight)
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| this.bgi = { img, w: size.w, h: size.h }
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| this._render()
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| }
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| img.src = this.bgi
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| }
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| _createParticles() {
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| this.particles = []
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| const random = (min, max) => Math.random() * (max - min) + min
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| for (let i = 0; i < this.particleCount; i++) {
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| const particle = new FogParticle(this.ctx, this.canvasWidth, this.canvasHeight)
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| particle.setPosition(
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| random(0, this.canvasWidth),
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| random(0, this.canvasHeight)
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| )
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| particle.setVelocity(
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| random(-this.maxVelocity, this.maxVelocity),
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| random(-this.maxVelocity, this.maxVelocity)
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| )
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| this.particles.push(particle)
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| }
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| }
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| _setImage() {
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| if (!this.particle) return
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| const img = new Image()
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| img.onload = () => this.particles.forEach(p => p.setImage(img))
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| img.src = this.particle
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| }
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| _render() {
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| if (this.bgi) {
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| this.ctx.drawImage(this.bgi.img, 0, 0, this.bgi.w, this.bgi.h)
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| } else {
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| this.ctx.fillStyle = "rgba(0, 0, 0, 1)"
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| this.ctx.fillRect(0, 0, this.canvasWidth, this.canvasHeight)
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| }
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| this.particles.forEach(p => p.render())
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| requestAnimationFrame(this._render.bind(this))
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| }
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| }
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| class Eraser {
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| constructor({ bgCanvas, brushCanvas, bgi, radius = 120 } = {}) {
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| bgCanvas = this.bgCanvas = document.querySelector(bgCanvas)
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| this.brushCanvas = document.querySelector(brushCanvas)
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| this.bgCtx = this.bgCanvas.getContext('2d')
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| this.brushCtx = this.brushCanvas.getContext('2d')
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| this.parentElement = this.bgCanvas.parentElement
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| const bcr = this.parentElement.getBoundingClientRect()
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| this.canvasWidth = this.bgCanvas.width = this.brushCanvas.width = bcr.width
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| this.canvasHeight = this.bgCanvas.height = this.brushCanvas.height = bcr.height
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| this.brushRadius = radius
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| this.bgi = new Image()
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| this.bgi.onload = this._attachEvents.bind(this)
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| this.bgi.src = bgi
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| this.utils = {
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| distanceBetween(point1, point2) {
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| return Math.sqrt(Math.pow(point2.x - point1.x, 2) + Math.pow(point2.y - point1.y, 2))
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| },
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| angleBetween(point1, point2) {
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| return Math.atan2(point2.x - point1.x, point2.y - point1.y)
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| },
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| getMousePos(e) {
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| const bcr = bgCanvas.getBoundingClientRect()
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| return {
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| x: e.clientX - bcr.left,
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| y: e.clientY - bcr.top
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| }
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| }
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| }
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| }
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| _attachEvents() {
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| this.parentElement.addEventListener('mousemove', this._onMouseMove.bind(this))
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| this.parentElement.addEventListener('mouseleave', this._onMouseLeave.bind(this))
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| }
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| _onMouseMove(e) {
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| const currentPoint = this.utils.getMousePos(e)
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| this.lastPoint = this.lastPoint || currentPoint
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| const dist = this.utils.distanceBetween(this.lastPoint, currentPoint)
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| const angle = this.utils.angleBetween(this.lastPoint, currentPoint)
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| for (let ii = 0; ii < dist; ii += 5) {
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| const x = this.lastPoint.x + (Math.sin(angle) * ii)
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| const y = this.lastPoint.y + (Math.cos(angle) * ii)
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| const brush = this.brushCtx.createRadialGradient(x, y, 0, x, y, this.brushRadius)
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| brush.addColorStop(0, 'rgba(0, 0, 0, 1)')
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| brush.addColorStop(.3, 'rgba(0, 0, 0, .1)')
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| brush.addColorStop(1, 'rgba(0, 0, 0, 0)')
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| this.brushCtx.fillStyle = brush
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| this.brushCtx.fillRect(
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| x - this.brushRadius,
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| y - this.brushRadius,
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| this.brushRadius * 2,
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| this.brushRadius * 2
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| )
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| }
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| this.lastPoint = currentPoint
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| this.bgCtx.globalCompositeOperation = 'source-over'
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| const size = coverImg(this.bgi, this.canvasWidth, this.canvasHeight)
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| this.bgCtx.drawImage(this.bgi, 0, 0, size.w, size.h)
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| this.bgCtx.globalCompositeOperation = 'destination-in'
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| this.bgCtx.drawImage(this.brushCanvas, 0, 0)
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| }
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| _onMouseLeave() {
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| this.lastPoint = null
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| }
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| }
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| const coverImg = (img, width, height) => {
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| const ratio = img.width / img.height
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| let w = width
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| let h = w / ratio
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| if (h < height) {
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| h = height
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| w = h * ratio
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| }
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| return { w, h }
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| }
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| // const bgi = 'http://saijogeorge.com/test/assets/images/mybackground.png'
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| const bgi = 'http://www.wallpaperup.com/uploads/wallpapers/2013/02/20/42433/big_thumb_a4789e7543f7b7467e6b1efcba41eaa0.jpg'
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| new Fog({
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| selector: '#fog',
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| particle: 'http://asista.pl/f/fog-particle.png',
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| density: 80,
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| bgi,
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| })
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| </script>
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| <div class="fog-container">
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| <canvas id="fog">
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| <canvas id="bg">
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| <canvas id="brush">
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| </div>
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