three.js/examples/js/shaders/AfterimageShader.js

( function () {

	/**
 * Afterimage shader
 * I created this effect inspired by a demo on codepen:
 * https://codepen.io/brunoimbrizi/pen/MoRJaN?page=1&
 */
	var AfterimageShader = {
		uniforms: {
			'damp': {
				value: 0.96
			},
			'tOld': {
				value: null
			},
			'tNew': {
				value: null
			}
		},
		vertexShader: [ 'varying vec2 vUv;', 'void main() {', '	vUv = uv;', '	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );', '}' ].join( '\n' ),
		fragmentShader: [ 'uniform float damp;', 'uniform sampler2D tOld;', 'uniform sampler2D tNew;', 'varying vec2 vUv;', 'vec4 when_gt( vec4 x, float y ) {', '	return max( sign( x - y ), 0.0 );', '}', 'void main() {', '	vec4 texelOld = texture2D( tOld, vUv );', '	vec4 texelNew = texture2D( tNew, vUv );', '	texelOld *= damp * when_gt( texelOld, 0.1 );', '	gl_FragColor = max(texelNew, texelOld);', '}' ].join( '\n' )
	};

	THREE.AfterimageShader = AfterimageShader;

} )();