curtains.js is a small vanilla WebGL javascript library that converts HTML elements containing images and videos into 3D WebGL textured planes, allowing you to animate them via shaders. You can define each plane size and position via CSS, add post processing, etc.
It was created by Martin Laxenaire and is released under the MIT license.
Basic example
<html>
<head>
<title>curtains.js basic example</title>
<style>
body {
/* make the body fits our viewport */
position: relative;
width: 100%;
height: 100vh;
margin: 0;
overflow: hidden;
}
#canvas {
/* make the canvas wrapper fits the document */
position: fixed;
top: 0;
right: 0;
bottom: 0;
left: 0;
}
.plane {
/* define the size of your plane */
width: 80%;
height: 80vh;
margin: 10vh auto;
}
.plane img {
/* hide the img element */
display: none;
}
</style>
</head>
<body>
<!-- div that will hold our WebGL canvas -->
<div id="canvas"></div>
<!-- div used to create our plane -->
<div class="plane">
<!-- image that will be used as texture by our plane -->
<img src="path/to/my-image.jpg" />
</div>
<script src="curtains.umd.min.js"></script>
<script>
const vertexShader = `
#ifdef GL_ES
precision mediump float;
#endif
// those are the mandatory attributes that the lib sets
attribute vec3 aVertexPosition;
attribute vec2 aTextureCoord;
// those are mandatory uniforms that the lib sets and that contain our model view and projection matrix
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
// our texture matrix that will handle image cover
uniform mat4 uTextureMatrix0;
// pass your vertex and texture coords to the fragment shader
varying vec3 vVertexPosition;
varying vec2 vTextureCoord;
void main() {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
// set the varyings
// here we use our texture matrix to calculate the accurate texture coords
vTextureCoord = (uTextureMatrix0 * vec4(aTextureCoord, 0.0, 1.0)).xy;
vVertexPosition = aVertexPosition;
}
`;
const fragmentShader = `
#ifdef GL_ES
precision mediump float;
#endif
// get our varyings
varying vec3 vVertexPosition;
varying vec2 vTextureCoord;
// the uniform we declared inside our javascript
uniform float uTime;
// our texture sampler (default name, to use a different name please refer to the documentation)
uniform sampler2D uSampler0;
void main() {
// get our texture coords from our varying
vec2 textureCoord = vTextureCoord;
// displace our pixels along the X axis based on our time uniform
// textures coords are ranging from 0.0 to 1.0 on both axis
textureCoord.x += sin(textureCoord.y * 25.0) * cos(textureCoord.x * 25.0) * (cos(uTime / 50.0)) / 25.0;
// map our texture with the texture matrix coords
gl_FragColor = texture2D(uSampler0, textureCoord);
}
`;
window.addEventListener("load", () => {
// set up our WebGL context and append the canvas to our wrapper
const curtains = new Curtains({
container: "canvas"
});
// get our plane element
const planeElement = document.querySelector(".plane");
// set our initial parameters (basic uniforms)
const params = {
vertexShader: vertexShader, // our vertex shader
fragmentShader: fragmentShader, // our fragment shader
uniforms: {
time: {
name: "uTime", // uniform name that will be passed to our shaders
type: "1f", // this means our uniform is a float
value: 0,
},
},
};
// create our plane using our curtains object, the bound HTML element and the parameters
const plane = new Plane(curtains, planeElement, params);
plane.onRender(() => {
// use the onRender method of our plane fired at each requestAnimationFrame call
plane.uniforms.time.value++; // update our time uniform value
});
});
</script>
</body>
</html>
Useful links
