three.js/examples/js/shaders/VerticalBlurShader.js

( function () {

	/**
 * Two pass Gaussian blur filter (horizontal and vertical blur shaders)
 * - see http://www.cake23.de/traveling-wavefronts-lit-up.html
 *
 * - 9 samples per pass
 * - standard deviation 2.7
 * - "h" and "v" parameters should be set to "1 / width" and "1 / height"
 */

	const VerticalBlurShader = {
		uniforms: {
			'tDiffuse': {
				value: null
			},
			'v': {
				value: 1.0 / 512.0
			}
		},
		vertexShader: /* glsl */`

		varying vec2 vUv;

		void main() {

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

		}`,
		fragmentShader: /* glsl */`

		uniform sampler2D tDiffuse;
		uniform float v;

		varying vec2 vUv;

		void main() {

			vec4 sum = vec4( 0.0 );

			sum += texture2D( tDiffuse, vec2( vUv.x, vUv.y - 4.0 * v ) ) * 0.051;
			sum += texture2D( tDiffuse, vec2( vUv.x, vUv.y - 3.0 * v ) ) * 0.0918;
			sum += texture2D( tDiffuse, vec2( vUv.x, vUv.y - 2.0 * v ) ) * 0.12245;
			sum += texture2D( tDiffuse, vec2( vUv.x, vUv.y - 1.0 * v ) ) * 0.1531;
			sum += texture2D( tDiffuse, vec2( vUv.x, vUv.y ) ) * 0.1633;
			sum += texture2D( tDiffuse, vec2( vUv.x, vUv.y + 1.0 * v ) ) * 0.1531;
			sum += texture2D( tDiffuse, vec2( vUv.x, vUv.y + 2.0 * v ) ) * 0.12245;
			sum += texture2D( tDiffuse, vec2( vUv.x, vUv.y + 3.0 * v ) ) * 0.0918;
			sum += texture2D( tDiffuse, vec2( vUv.x, vUv.y + 4.0 * v ) ) * 0.051;

			gl_FragColor = sum;

		}`
	};

	THREE.VerticalBlurShader = VerticalBlurShader;

} )();