examples/webgl_postprocessing_ssaa.html

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		<title>three.js webgl - postprocessing manual ssaa</title>
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		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - Unbiased Manual Supersampling Anti-Aliasing (SSAA) pass by <a href="https://clara.io" target="_blank" rel="noopener">Ben Houston</a><br/><br/>
			This example shows how to unbias the rounding errors accumulated using high number of SSAA samples on a 8-bit per channel buffer.<br/><br/>
			Turn off the "unbiased" feature to see the banding that results from accumulated rounding errors.
		</div>

		<div id="container"></div>

		<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js",
					"three/addons/": "./jsm/"
				}
			}
		</script>

		<script type="module">

			import * as THREE from 'three';

			import Stats from 'three/addons/libs/stats.module.js';
			import { GUI } from 'three/addons/libs/lil-gui.module.min.js';

			import { EffectComposer } from 'three/addons/postprocessing/EffectComposer.js';
			import { SSAARenderPass } from 'three/addons/postprocessing/SSAARenderPass.js';
			import { OutputPass } from 'three/addons/postprocessing/OutputPass.js';

			let scene, renderer, composer;
			let cameraP, ssaaRenderPassP;
			let cameraO, ssaaRenderPassO;
			let gui, stats;

			const params = {
				sampleLevel: 4,
				unbiased: true,
				camera: 'perspective',
				clearColor: 'black',
				clearAlpha: 1.0,
				viewOffsetX: 0,
				autoRotate: true

			};

			init();

			clearGui();

			function clearGui() {

				if ( gui ) gui.destroy();

				gui = new GUI();

				gui.add( params, 'unbiased' );
				gui.add( params, 'sampleLevel', {
					'Level 0: 1 Sample': 0,
					'Level 1: 2 Samples': 1,
					'Level 2: 4 Samples': 2,
					'Level 3: 8 Samples': 3,
					'Level 4: 16 Samples': 4,
					'Level 5: 32 Samples': 5
				} );
				gui.add( params, 'camera', [ 'perspective', 'orthographic' ] );
				gui.add( params, 'clearColor', [ 'black', 'white', 'blue', 'green', 'red' ] );
				gui.add( params, 'clearAlpha', 0, 1 );
				gui.add( params, 'viewOffsetX', - 100, 100 );
				gui.add( params, 'autoRotate' );

				gui.open();

			}

			function init() {

				const container = document.getElementById( 'container' );

				const width = window.innerWidth || 1;
				const height = window.innerHeight || 1;
				const aspect = width / height;
				const devicePixelRatio = window.devicePixelRatio || 1;

				renderer = new THREE.WebGLRenderer();
				renderer.setPixelRatio( devicePixelRatio );
				renderer.setSize( width, height );
				renderer.setAnimationLoop( animate );
				document.body.appendChild( renderer.domElement );

				stats = new Stats();
				container.appendChild( stats.dom );

				cameraP = new THREE.PerspectiveCamera( 65, aspect, 3, 10 );
				cameraP.position.z = 7;
				cameraP.setViewOffset( width, height, params.viewOffsetX, 0, width, height );

				cameraO = new THREE.OrthographicCamera( width / - 2, width / 2, height / 2, height / - 2, 3, 10 );
				cameraO.position.z = 7;

				const fov = THREE.MathUtils.degToRad( cameraP.fov );
				const hyperfocus = ( cameraP.near + cameraP.far ) / 2;
				const _height = 2 * Math.tan( fov / 2 ) * hyperfocus;
				cameraO.zoom = height / _height;


				scene = new THREE.Scene();

				const group = new THREE.Group();
				scene.add( group );

				const light = new THREE.PointLight( 0xefffef, 500 );
				light.position.z = 10;
				light.position.y = - 10;
				light.position.x = - 10;
				scene.add( light );

				const light2 = new THREE.PointLight( 0xffefef, 500 );
				light2.position.z = 10;
				light2.position.x = - 10;
				light2.position.y = 10;
				scene.add( light2 );

				const light3 = new THREE.PointLight( 0xefefff, 500 );
				light3.position.z = 10;
				light3.position.x = 10;
				light3.position.y = - 10;
				scene.add( light3 );

				const light4 = new THREE.AmbientLight( 0xffffff, 0.2 );
				scene.add( light4 );

				const geometry = new THREE.SphereGeometry( 3, 48, 24 );

				for ( let i = 0; i < 120; i ++ ) {

					const material = new THREE.MeshStandardMaterial();
					material.roughness = 0.5 * Math.random() + 0.25;
					material.metalness = 0;
					material.color.setHSL( Math.random(), 1.0, 0.3 );

					const mesh = new THREE.Mesh( geometry, material );
					mesh.position.x = Math.random() * 4 - 2;
					mesh.position.y = Math.random() * 4 - 2;
					mesh.position.z = Math.random() * 4 - 2;
					mesh.rotation.x = Math.random();
					mesh.rotation.y = Math.random();
					mesh.rotation.z = Math.random();

					mesh.scale.setScalar( Math.random() * 0.2 + 0.05 );
					group.add( mesh );

				}

				// postprocessing

				composer = new EffectComposer( renderer );
				composer.setPixelRatio( 1 ); // ensure pixel ratio is always 1 for performance reasons
				ssaaRenderPassP = new SSAARenderPass( scene, cameraP );
				composer.addPass( ssaaRenderPassP );
				ssaaRenderPassO = new SSAARenderPass( scene, cameraO );
				composer.addPass( ssaaRenderPassO );
				const outputPass = new OutputPass();
				composer.addPass( outputPass );

				window.addEventListener( 'resize', onWindowResize );

			}

			function onWindowResize() {

				const width = window.innerWidth;
				const height = window.innerHeight;
				const aspect = width / height;

				cameraP.aspect = aspect;
				cameraP.setViewOffset( width, height, params.viewOffsetX, 0, width, height );
				cameraO.updateProjectionMatrix();

				cameraO.left = - height * aspect;
				cameraO.right = height * aspect;
				cameraO.top = height;
				cameraO.bottom = - height;
				cameraO.updateProjectionMatrix();

				renderer.setSize( width, height );
				composer.setSize( width, height );

			}

			function animate() {

				stats.begin();

				if ( params.autoRotate ) {

					for ( let i = 0; i < scene.children.length; i ++ ) {

						const child = scene.children[ i ];

						child.rotation.x += 0.005;
						child.rotation.y += 0.01;

					}

				}

				let newColor = ssaaRenderPassP.clearColor;

				switch ( params.clearColor ) {

					case 'blue': newColor = 0x0000ff; break;
					case 'red': newColor = 0xff0000; break;
					case 'green': newColor = 0x00ff00; break;
					case 'white': newColor = 0xffffff; break;
					case 'black': newColor = 0x000000; break;

				}

				ssaaRenderPassP.clearColor = ssaaRenderPassO.clearColor = newColor;
				ssaaRenderPassP.clearAlpha = ssaaRenderPassO.clearAlpha = params.clearAlpha;

				ssaaRenderPassP.sampleLevel = ssaaRenderPassO.sampleLevel = params.sampleLevel;
				ssaaRenderPassP.unbiased = ssaaRenderPassO.unbiased = params.unbiased;

				ssaaRenderPassP.enabled = ( params.camera === 'perspective' );
				ssaaRenderPassO.enabled = ( params.camera === 'orthographic' );

				cameraP.view.offsetX = params.viewOffsetX;

				composer.render();

				stats.end();

			}

		</script>
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