three.js/examples/js/shaders/DotScreenShader.js

( function () {

	/**
 * Dot screen shader
 * based on glfx.js sepia shader
 * https://github.com/evanw/glfx.js
 */

	const DotScreenShader = {
		uniforms: {
			'tDiffuse': {
				value: null
			},
			'tSize': {
				value: new THREE.Vector2( 256, 256 )
			},
			'center': {
				value: new THREE.Vector2( 0.5, 0.5 )
			},
			'angle': {
				value: 1.57
			},
			'scale': {
				value: 1.0
			}
		},
		vertexShader: /* glsl */`

		varying vec2 vUv;

		void main() {

			vUv = uv;
			gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

		}`,
		fragmentShader: /* glsl */`

		uniform vec2 center;
		uniform float angle;
		uniform float scale;
		uniform vec2 tSize;

		uniform sampler2D tDiffuse;

		varying vec2 vUv;

		float pattern() {

			float s = sin( angle ), c = cos( angle );

			vec2 tex = vUv * tSize - center;
			vec2 point = vec2( c * tex.x - s * tex.y, s * tex.x + c * tex.y ) * scale;

			return ( sin( point.x ) * sin( point.y ) ) * 4.0;

		}

		void main() {

			vec4 color = texture2D( tDiffuse, vUv );

			float average = ( color.r + color.g + color.b ) / 3.0;

			gl_FragColor = vec4( vec3( average * 10.0 - 5.0 + pattern() ), color.a );

		}`
	};

	THREE.DotScreenShader = DotScreenShader;

} )();