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

( function () {

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

	var 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: [ 'varying vec2 vUv;', 'void main() {', '	vUv = uv;', '	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );', '}' ].join( '\n' ),
		fragmentShader: [ '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 );', '}' ].join( '\n' )
	};

	THREE.DotScreenShader = DotScreenShader;

} )();