So I wanna create glitch effect on canvas, that get every frame from webcam. Code below. Here the code, which works only if width: 200px height: 200px
if change this value to width: 600px height: 400px
(container size), glitch effect stops working. Here's code where you can change value canvas.width, canvas.height, and see it by yourself CodePen. Does someone know, what a reason for that and how fix it? Or it's some kinda limitations on feTurbulence?
const addEffect = (element, filter) => {
element.style.webkitFilter = `url(#${filter})`;
element.style.mozFilter = `url(#${filter})`;
element.style.filter = `url(#${filter})`;
};
const runEffect = () => {
const turb = document.querySelector('#displacement feTurbulence');
const turbVal = { val: 0.000001 };
const btTl = new TimelineLite({
paused: true,
onUpdate() {
turb.setAttribute('baseFrequency', `0 ${turbVal.val}`);
},
});
btTl.to(turbVal, 0.2, { val: 0.3 });
btTl.to(turbVal, 0.2, { val: 0.000001 });
btTl.restart();
};
const URL = window.URL || window.webkitURL || window.mozURL || window.msURL;
const video = document.createElement('video');
navigator.mediaDevices.getUserMedia({
video: true,
}).then((stream) => {
video.src = URL.createObjectURL(stream);
});
const canvas = document.querySelector('#canvas');
const ctx = canvas.getContext('2d');
addEffect(canvas, 'displacement');
setInterval(() => runEffect(), 1000);
const loop = () => {
ctx.drawImage(video, 0, 0, canvas.width, canvas.height);
requestAnimationFrame(loop);
};
loop();
.container {
margin: 0 auto;
width: 600px;
height: 400px;
margin-top: 100px;
box-shadow: 1px 1px 20px #666;
position: relative;
}
.container > canvas {
position: absolute;
background-color: red;
mix-blend-mode: darken;
}
svg {
position: absolute;
width: 0;
height: 0;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/1.18.0/TweenMax.min.js"></script>
<div class="container">
<canvas id="canvas" width="200px" height="200px"></canvas>
<svg xmlns="http://www.w3.org/2000/svg" version="1.1" class="svg-filters">
<defs>
<filter id="displacement">
<feTurbulence type="fractalNoise" baseFrequency="0.0" numOctaves="1" result="warp"></feTurbulence>
<feDisplacementMap xChannelSelector="R" yChannelSelector="G" scale="80" in="SourceGraphic" in2="warp" />
</filter>
</defs>
</svg>
</div>
It seems that there is some bug causing the canvas to not be redrawn fast enough when it is larger in size. You can force it to redraw by tweaking a CSS property, such as opacity in the example below.
const addEffect = (element, filter) => {
element.style.webkitFilter = `url(#${filter})`;
element.style.mozFilter = `url(#${filter})`;
element.style.filter = `url(#${filter})`;
};
const runEffect = () => {
const turb = document.querySelector('#displacement feTurbulence');
const turbVal = { val: 0.000001 };
const btTl = new TimelineLite({
paused: true,
onUpdate() {
turb.setAttribute('baseFrequency', `0 ${turbVal.val}`);
},
});
btTl.to(turbVal, 0.2, { val: 0.3 });
btTl.to(turbVal, 0.2, { val: 0.000001 });
btTl.restart();
};
const URL = window.URL || window.webkitURL || window.mozURL || window.msURL;
const video = document.createElement('video');
navigator.mediaDevices.getUserMedia({
video: true,
}).then((stream) => {
video.src = URL.createObjectURL(stream);
});
const canvas = document.querySelector('#canvas');
const ctx = canvas.getContext('2d');
addEffect(canvas, 'displacement');
setInterval(() => runEffect(), 1000);
/**
* Use a hack to force the canvas to redraw
*/
const refreshCanvas = function(){
let on = true;
return () => {
on = !on;
canvas.style.opacity = on ? 1 : 0.999;
}
}();
const loop = (timestamp) => {
ctx.drawImage(video, 0, 0, canvas.width, canvas.height);
refreshCanvas(); // call our hack
requestAnimationFrame(loop);
};
loop();
.container {
margin: 0 auto;
width: 600px;
height: 400px;
margin-top: 100px;
box-shadow: 1px 1px 20px #666;
position: relative;
}
.container > canvas {
position: absolute;
background-color: red;
mix-blend-mode: darken;
}
svg {
position: absolute;
width: 0;
height: 0;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/1.18.0/TweenMax.min.js"></script>
<div class="container">
<canvas id="canvas" width="600" height="400"></canvas>
<svg xmlns="http://www.w3.org/2000/svg" version="1.1" class="svg-filters">
<defs>
<filter id="displacement">
<feTurbulence type="fractalNoise" baseFrequency="0.0" numOctaves="1" result="warp"></feTurbulence>
<feDisplacementMap xChannelSelector="R" yChannelSelector="G" scale="80" in="SourceGraphic" in2="warp" />
</filter>
</defs>
</svg>
</div>