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		<title>three.js - WebGPU - Backdrop Area</title>
		<meta charset="utf-8">
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		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> WebGPU - Backdrop Area
		</div>

		<script async src="https://unpkg.com/es-module-shims@1.8.0/dist/es-module-shims.js"></script>

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

		<script type="module">

			import * as THREE from 'three';
			import { color, depth, depthTexture, toneMapping, viewportSharedTexture, viewportMipTexture, viewportTopLeft, checker, uv, modelScale, MeshBasicNodeMaterial } from 'three/nodes';
 
			import { GUI } from 'three/addons/libs/lil-gui.module.min.js';

			import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';

			import WebGPU from 'three/addons/capabilities/WebGPU.js';
			import WebGPURenderer from 'three/addons/renderers/webgpu/WebGPURenderer.js';

			import { OrbitControls } from 'three/addons/controls/OrbitControls.js';

			let camera, scene, renderer;
			let mixer, clock;

			init();

			function init() {

				if ( WebGPU.isAvailable() === false ) {

					document.body.appendChild( WebGPU.getErrorMessage() );

					throw new Error( 'No WebGPU support' );

				}

				camera = new THREE.PerspectiveCamera( 50, window.innerWidth / window.innerHeight, 0.25, 25 );
				camera.position.set( 3, 2, 3 );

				scene = new THREE.Scene();
				scene.background = new THREE.Color( 0x333333 );
				camera.lookAt( 0, 1, 0 );

				clock = new THREE.Clock();

				// model

				const loader = new GLTFLoader();
				loader.load( 'models/gltf/Michelle.glb', function ( gltf ) {

					const object = gltf.scene;
					mixer = new THREE.AnimationMixer( object );

					const action = mixer.clipAction( gltf.animations[ 0 ] );
					action.play();

					scene.add( object );

				} );

				// volume

				const depthDistance = depthTexture().distance( depth );
				const depthAlphaNode = depthDistance.oneMinus().smoothstep( .90, 2 ).mul( 20 ).saturate();
				const depthBlurred = viewportMipTexture().bicubic( depthDistance.smoothstep( 0, .6 ).mul( 40 * 5 ).clamp( 0, 5 ) );

				const blurredBlur = new MeshBasicNodeMaterial();
				blurredBlur.backdropNode = depthBlurred.add( depthAlphaNode.mix( color( 0x0066ff ), 0 ) );
				blurredBlur.transparent = true;
				blurredBlur.side = THREE.DoubleSide;

				const volumeMaterial = new MeshBasicNodeMaterial();
				volumeMaterial.colorNode = color( 0x0066ff );
				volumeMaterial.backdropNode = viewportSharedTexture();
				volumeMaterial.backdropAlphaNode = depthAlphaNode;
				volumeMaterial.transparent = true;
				volumeMaterial.side = THREE.DoubleSide;

				const depthMaterial = new MeshBasicNodeMaterial();
				depthMaterial.backdropNode = depthAlphaNode;
				depthMaterial.transparent = true;
				depthMaterial.side = THREE.DoubleSide;

				const bicubicMaterial = new MeshBasicNodeMaterial();
				bicubicMaterial.backdropNode = viewportMipTexture().bicubic( 5 ); // @TODO: Move to alpha value [ 0, 1 ]
				bicubicMaterial.backdropAlphaNode = checker( uv().mul( 3 ).mul( modelScale.xy ) );
				bicubicMaterial.opacityNode = bicubicMaterial.backdropAlphaNode;
				bicubicMaterial.transparent = true;
				bicubicMaterial.side = THREE.DoubleSide;

				const pixelMaterial = new MeshBasicNodeMaterial();
				pixelMaterial.backdropNode = viewportSharedTexture( viewportTopLeft.mul( 100 ).floor().div( 100 ) );
				pixelMaterial.transparent = true;

				// box / floor

				const box = new THREE.Mesh( new THREE.BoxGeometry( 2, 2, 2 ), volumeMaterial );
				box.position.set( 0, 1, 0 );
				scene.add( box );

				const floor = new THREE.Mesh( new THREE.BoxGeometry( 1.99, .01, 1.99 ), new MeshBasicNodeMaterial( { color: 0x333333 } ) );
				floor.position.set( 0, 0, 0 );
				scene.add( floor );

				// renderer

				renderer = new WebGPURenderer();
				renderer.stencil = false;
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.setAnimationLoop( animate );
				renderer.toneMappingNode = toneMapping( THREE.LinearToneMapping, .15 );
				document.body.appendChild( renderer.domElement );

				const controls = new OrbitControls( camera, renderer.domElement );
				controls.target.set( 0, 1, 0 );
				controls.update();

				window.addEventListener( 'resize', onWindowResize );

				// gui

				const materials = {
					'blurred': blurredBlur,
					'volume': volumeMaterial,
					'depth': depthMaterial,
					'bicubic': bicubicMaterial,
					'pixel': pixelMaterial
				};

				const gui = new GUI();
				const options = { material: 'blurred' };

				box.material = materials[ options.material ];

				gui.add( box.scale, 'x', 0.1, 2, 0.01 );
				gui.add( box.scale, 'z', 0.1, 2, 0.01 );
				gui.add( options, 'material', Object.keys( materials ) ).onChange( name => {

					box.material = materials[ name ];

				} );

			}

			function onWindowResize() {

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

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

			}

			function animate() {

				const delta = clock.getDelta();

				if ( mixer ) mixer.update( delta );

				renderer.render( scene, camera );

			}

		</script>
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