three.js/examples/js/shaders/TriangleBlurShader.js

( function () {

	/**
 * Triangle blur shader
 * based on glfx.js triangle blur shader
 * https://github.com/evanw/glfx.js
 *
 * A basic blur filter, which convolves the image with a
 * pyramid filter. The pyramid filter is separable and is applied as two
 * perpendicular triangle filters.
 */

	var TriangleBlurShader = {
		uniforms: {
			'texture': {
				value: null
			},
			'delta': {
				value: new THREE.Vector2( 1, 1 )
			}
		},
		vertexShader: [ 'varying vec2 vUv;', 'void main() {', '	vUv = uv;', '	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );', '}' ].join( '\n' ),
		fragmentShader: [ '#include <common>', '#define ITERATIONS 10.0', 'uniform sampler2D texture;', 'uniform vec2 delta;', 'varying vec2 vUv;', 'void main() {', '	vec4 color = vec4( 0.0 );', '	float total = 0.0;', // randomize the lookup values to hide the fixed number of samples
			'	float offset = rand( vUv );', '	for ( float t = -ITERATIONS; t <= ITERATIONS; t ++ ) {', '		float percent = ( t + offset - 0.5 ) / ITERATIONS;', '		float weight = 1.0 - abs( percent );', '		color += texture2D( texture, vUv + delta * percent ) * weight;', '		total += weight;', '	}', '	gl_FragColor = color / total;', '}' ].join( '\n' )
	};

	THREE.TriangleBlurShader = TriangleBlurShader;

} )();