examples/webgl_modifier_curve.html

<!DOCTYPE html>
<html lang="en">
	<head>
		<title>three.js webgl - curve modifier</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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		<link type="text/css" rel="stylesheet" href="main.css" />
	</head>
	<body>
		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> webgl - curve modifier
		</div>

		<!-- Import maps polyfill -->
		<!-- Remove this when import maps will be widely supported -->
		<script async src="https://unpkg.com/es-module-shims@1.3.6/dist/es-module-shims.js"></script>

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

		<script type="module">
			import * as THREE from 'three';
			import { TransformControls } from 'three/addons/controls/TransformControls.js';
			import Stats from 'three/addons/libs/stats.module.js';
			import { Flow } from 'three/addons/modifiers/CurveModifier.js';
			import { FontLoader } from 'three/addons/loaders/FontLoader.js';
			import { TextGeometry } from 'three/addons/geometries/TextGeometry.js';

			const ACTION_SELECT = 1, ACTION_NONE = 0;
			const curveHandles = [];
			const mouse = new THREE.Vector2();

			let stats;
			let scene,
				camera,
				renderer,
				rayCaster,
				control,
				flow,
				action = ACTION_NONE;

			init();
			animate();

			function init() {

				scene = new THREE.Scene();

				camera = new THREE.PerspectiveCamera(
					40,
					window.innerWidth / window.innerHeight,
					1,
					1000
				);
				camera.position.set( 2, 2, 4 );
				camera.lookAt( scene.position );

				const initialPoints = [
					{ x: 1, y: 0, z: - 1 },
					{ x: 1, y: 0, z: 1 },
					{ x: - 1, y: 0, z: 1 },
					{ x: - 1, y: 0, z: - 1 },
				];

				const boxGeometry = new THREE.BoxGeometry( 0.1, 0.1, 0.1 );
				const boxMaterial = new THREE.MeshBasicMaterial();

				for ( const handlePos of initialPoints ) {

					const handle = new THREE.Mesh( boxGeometry, boxMaterial );
					handle.position.copy( handlePos );
					curveHandles.push( handle );
					scene.add( handle );

				}

				const curve = new THREE.CatmullRomCurve3(
					curveHandles.map( ( handle ) => handle.position )
				);
				curve.curveType = 'centripetal';
				curve.closed = true;

				const points = curve.getPoints( 50 );
				const line = new THREE.LineLoop(
					new THREE.BufferGeometry().setFromPoints( points ),
					new THREE.LineBasicMaterial( { color: 0x00ff00 } )
				);

				scene.add( line );

				//

				const light = new THREE.DirectionalLight( 0xffaa33 );
				light.position.set( - 10, 10, 10 );
				light.intensity = 1.0;
				scene.add( light );

				const light2 = new THREE.AmbientLight( 0x003973 );
				light2.intensity = 1.0;
				scene.add( light2 );

				//

				const loader = new FontLoader();
				loader.load( 'fonts/helvetiker_regular.typeface.json', function ( font ) {

					const geometry = new TextGeometry( 'Hello three.js!', {
						font: font,
						size: 0.2,
						height: 0.05,
						curveSegments: 12,
						bevelEnabled: true,
						bevelThickness: 0.02,
						bevelSize: 0.01,
						bevelOffset: 0,
						bevelSegments: 5,
					} );

					geometry.rotateX( Math.PI );

					const material = new THREE.MeshStandardMaterial( {
						color: 0x99ffff
					} );

					const objectToCurve = new THREE.Mesh( geometry, material );

					flow = new Flow( objectToCurve );
					flow.updateCurve( 0, curve );
					scene.add( flow.object3D );

				} );

				//

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

				renderer.domElement.addEventListener( 'pointerdown', onPointerDown );

				rayCaster = new THREE.Raycaster();
				control = new TransformControls( camera, renderer.domElement );
				control.addEventListener( 'dragging-changed', function ( event ) {

					if ( ! event.value ) {

						const points = curve.getPoints( 50 );
						line.geometry.setFromPoints( points );
						flow.updateCurve( 0, curve );

					}

				} );

				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 onPointerDown( event ) {

				action = ACTION_SELECT;
				mouse.x = ( event.clientX / window.innerWidth ) * 2 - 1;
				mouse.y = - ( event.clientY / window.innerHeight ) * 2 + 1;

			}

			function animate() {

				requestAnimationFrame( animate );

				if ( action === ACTION_SELECT ) {

					rayCaster.setFromCamera( mouse, camera );
					action = ACTION_NONE;
					const intersects = rayCaster.intersectObjects( curveHandles, false );
					if ( intersects.length ) {

						const target = intersects[ 0 ].object;
						control.attach( target );
						scene.add( control );

					}

				}

				if ( flow ) {

					flow.moveAlongCurve( 0.001 );

				}

				render();

			}

			function render() {

				renderer.render( scene, camera );

				stats.update();

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