examples/webgl_clipculldistance.html

<!DOCTYPE html>
<html lang="en">
	<head>
		<title>three.js WebGL 2 - clip cull distance</title>
		<meta charset="utf-8" />
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0" />
		<link type="text/css" rel="stylesheet" href="main.css" />
	</head>
	<body>
		<div id="container"></div>

		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener" >three.js</a> - vertex shader clipping via
			<a href="https://registry.khronos.org/webgl/extensions/WEBGL_clip_cull_distance/" target="_blank" rel="noopener" >WEBGL_clip_cull_distance</a>
			<div id="notSupported" style="display:none">WEBGL_clip_cull_distance not supported</div>
		</div>

		<script id="vertexShader" type="x-shader/x-vertex">

			uniform float time;

			varying vec4 vColor;

			void main() {

				vColor = color;

				#ifdef USE_CLIP_DISTANCE
					vec4 worldPosition = modelMatrix * vec4( position, 1.0 );
					gl_ClipDistance[ 0 ] = worldPosition.x - sin( time ) * ( 0.5 );
				#endif

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

			}

		</script>

		<script id="fragmentShader" type="x-shader/x-fragment">

			varying vec4 vColor;

			void main() {

				gl_FragColor = vColor;

			}

		</script>

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

		<script type="module">
			import * as THREE from 'three';
			import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
			import Stats from 'three/addons/libs/stats.module.js';

			let camera, controls, clock, scene, renderer, stats;

			let material;

			init();

			function init() {

				camera = new THREE.PerspectiveCamera( 50, window.innerWidth / window.innerHeight, 1, 10 );
				camera.position.z = 2;

				scene = new THREE.Scene();

				clock = new THREE.Clock();

				//

				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.setAnimationLoop( animate );
				document.body.appendChild( renderer.domElement );

				if ( renderer.extensions.has( 'WEBGL_clip_cull_distance' ) === false ) {

					document.getElementById( 'notSupported' ).style.display = '';
					return;

				}

				const ext = renderer
					.getContext()
					.getExtension( 'WEBGL_clip_cull_distance' );
				const gl = renderer.getContext();

				gl.enable( ext.CLIP_DISTANCE0_WEBGL );

				// geometry

				const vertexCount = 200 * 3;

				const geometry = new THREE.BufferGeometry();

				const positions = [];
				const colors = [];

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

					// adding x,y,z
					positions.push( Math.random() - 0.5 );
					positions.push( Math.random() - 0.5 );
					positions.push( Math.random() - 0.5 );

					// adding r,g,b,a
					colors.push( Math.random() * 255 );
					colors.push( Math.random() * 255 );
					colors.push( Math.random() * 255 );
					colors.push( Math.random() * 255 );

				}

				const positionAttribute = new THREE.Float32BufferAttribute( positions, 3 );
				const colorAttribute = new THREE.Uint8BufferAttribute( colors, 4 );
				colorAttribute.normalized = true;

				geometry.setAttribute( 'position', positionAttribute );
				geometry.setAttribute( 'color', colorAttribute );

				// material

				material = new THREE.ShaderMaterial( {

					uniforms: {
						time: { value: 1.0 }
					},
					vertexShader: document.getElementById( 'vertexShader' ).textContent,
					fragmentShader: document.getElementById( 'fragmentShader' ).textContent,
					side: THREE.DoubleSide,
					transparent: true,
					vertexColors: true

				} );

				material.extensions.clipCullDistance = true;

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

				//

				controls = new OrbitControls( camera, renderer.domElement );

				//

				stats = new Stats();
				document.body.appendChild( stats.dom );

				window.addEventListener( 'resize', onWindowResize );

			}

			function onWindowResize() {

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

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

			}

			function animate() {

				controls.update();
				stats.update();

				material.uniforms.time.value = clock.getElapsedTime();

				renderer.render( scene, camera );

			}
		</script>
	</body>
</html>