examples/webgl_postprocessing_sobel.html

<!DOCTYPE html>
<html lang="en">
	<head>
		<title>three.js webgl - postprocessing - sobel (edge detection)</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
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			body {
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				padding:0;
				margin:0;
				font-weight: bold;
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			#info {
				position: absolute;
				top: 0px;
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				font-family:Monospace;
				font-size:13px;
				text-align:center;
			}

			a {
				color: #ffffff;
			}
		</style>
	</head>
	<body>

		<script src="../build/three.js"></script>
		<script src="js/controls/OrbitControls.js"></script>
		<script src="js/WebGL.js"></script>
		<script src="js/libs/dat.gui.min.js"></script>

		<script src="js/shaders/CopyShader.js"></script>
		<script src="js/shaders/LuminosityShader.js"></script>
		<script src="js/shaders/SobelOperatorShader.js"></script>

		<script src="js/postprocessing/EffectComposer.js"></script>
		<script src="js/postprocessing/RenderPass.js"></script>
		<script src="js/postprocessing/ShaderPass.js"></script>

		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener noreferrer">three.js</a> - webgl - postprocessing - sobel (edge detection)
		</div>

		<script>

			if ( WEBGL.isWebGLAvailable() === false ) {

				document.body.appendChild( WEBGL.getWebGLErrorMessage() );

			}

			var camera, scene, renderer, composer;

			var effectSobel;

			var params = {
				enable: true
			};

			init();
			animate();

			function init() {

				//

				scene = new THREE.Scene();

				camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 1, 1000 );
				camera.position.set( 0, 10, 25 );
				camera.lookAt( scene.position );

				//

				var geometry = new THREE.TorusKnotBufferGeometry( 8, 3, 256, 32, 2, 3 );
				var material = new THREE.MeshPhongMaterial( { color: 0xffff00 } );

				var mesh = new THREE.Mesh( geometry, material );
				scene.add( mesh );

				//

				var ambientLight = new THREE.AmbientLight( 0xcccccc, 0.4 );
				scene.add( ambientLight );

				var pointLight = new THREE.PointLight( 0xffffff, 0.8 );
				camera.add( pointLight );
				scene.add( camera );

				//

				renderer = new THREE.WebGLRenderer();
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				document.body.appendChild( renderer.domElement );

				// postprocessing

				composer = new THREE.EffectComposer( renderer );
				var renderPass = new THREE.RenderPass( scene, camera );
				composer.addPass( renderPass );

				// color to grayscale conversion

				var effectGrayScale = new THREE.ShaderPass( THREE.LuminosityShader );
				composer.addPass( effectGrayScale );

				// you might want to use a gaussian blur filter before
				// the next pass to improve the result of the Sobel operator

				// Sobel operator

				effectSobel = new THREE.ShaderPass( THREE.SobelOperatorShader );
				effectSobel.uniforms[ "resolution" ].value.x = window.innerWidth;
				effectSobel.uniforms[ "resolution" ].value.y = window.innerHeight;
				composer.addPass( effectSobel );

				var controls = new THREE.OrbitControls( camera );

				//

				var gui = new dat.GUI();

				gui.add( params, 'enable' );
				gui.open();

				//

				window.addEventListener( 'resize', onWindowResize, false );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );
				composer.setSize( window.innerWidth, window.innerHeight );

				effectSobel.uniforms[ "resolution" ].value.x = window.innerWidth;
				effectSobel.uniforms[ "resolution" ].value.y = window.innerHeight;

			}

			function animate() {

				requestAnimationFrame( animate );

				if ( params.enable === true ) {

					composer.render();

				} else {

					renderer.render( scene, camera );

				}

			}

		</script>

	</body>
</html>