manual/examples/canvas-textured-labels-scale-to-fit.html

<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - Canvas Textured Labels Scale to Fit</title>
    <style>
    html, body {
        height: 100%;
        margin: 0;
    }
    #c {
        width: 100%;
        height: 100%;
        display: block;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
  </body>
<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js",
    "three/addons/": "../../examples/jsm/"
  }
}
</script>

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

function main() {

	const canvas = document.querySelector( '#c' );
	const renderer = new THREE.WebGLRenderer( { antialias: true, canvas } );

	const fov = 75;
	const aspect = 2; // the canvas default
	const near = 0.1;
	const far = 50;
	const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
	camera.position.set( 0, 2, 5 );

	const controls = new OrbitControls( camera, canvas );
	controls.target.set( 0, 2, 0 );
	controls.update();

	const scene = new THREE.Scene();
	scene.background = new THREE.Color( 'white' );

	function addLight( position ) {

		const color = 0xFFFFFF;
		const intensity = 3;
		const light = new THREE.DirectionalLight( color, intensity );
		light.position.set( ...position );
		scene.add( light );
		scene.add( light.target );

	}

	addLight( [ - 3, 1, 1 ] );
	addLight( [ 2, 1, .5 ] );

	const bodyRadiusTop = .4;
	const bodyRadiusBottom = .2;
	const bodyHeight = 2;
	const bodyRadialSegments = 6;
	const bodyGeometry = new THREE.CylinderGeometry(
		bodyRadiusTop, bodyRadiusBottom, bodyHeight, bodyRadialSegments );

	const headRadius = bodyRadiusTop * 0.8;
	const headLonSegments = 12;
	const headLatSegments = 5;
	const headGeometry = new THREE.SphereGeometry(
		headRadius, headLonSegments, headLatSegments );

	const labelGeometry = new THREE.PlaneGeometry( 1, 1 );

	function makeLabelCanvas( baseWidth, size, name ) {

		const borderSize = 2;
		const ctx = document.createElement( 'canvas' ).getContext( '2d' );
		const font = `${size}px bold sans-serif`;
		ctx.font = font;
		// measure how long the name will be
		const textWidth = ctx.measureText( name ).width;

		const doubleBorderSize = borderSize * 2;
		const width = baseWidth + doubleBorderSize;
		const height = size + doubleBorderSize;
		ctx.canvas.width = width;
		ctx.canvas.height = height;

		// need to set font again after resizing canvas
		ctx.font = font;
		ctx.textBaseline = 'middle';
		ctx.textAlign = 'center';

		ctx.fillStyle = 'blue';
		ctx.fillRect( 0, 0, width, height );

		// scale to fit but don't stretch
		const scaleFactor = Math.min( 1, baseWidth / textWidth );
		ctx.translate( width / 2, height / 2 );
		ctx.scale( scaleFactor, 1 );
		ctx.fillStyle = 'white';
		ctx.fillText( name, 0, 0 );

		return ctx.canvas;

	}

	function makePerson( x, labelWidth, size, name, color ) {

		const canvas = makeLabelCanvas( labelWidth, size, name );
		const texture = new THREE.CanvasTexture( canvas );
		// because our canvas is likely not a power of 2
		// in both dimensions set the filtering appropriately.
		texture.minFilter = THREE.LinearFilter;
		texture.wrapS = THREE.ClampToEdgeWrapping;
		texture.wrapT = THREE.ClampToEdgeWrapping;

		const labelMaterial = new THREE.MeshBasicMaterial( {
			map: texture,
			side: THREE.DoubleSide,
			transparent: true,
		} );
		const bodyMaterial = new THREE.MeshPhongMaterial( {
			color,
			flatShading: true,
		} );

		const root = new THREE.Object3D();
		root.position.x = x;

		const body = new THREE.Mesh( bodyGeometry, bodyMaterial );
		root.add( body );
		body.position.y = bodyHeight / 2;

		const head = new THREE.Mesh( headGeometry, bodyMaterial );
		root.add( head );
		head.position.y = bodyHeight + headRadius * 1.1;

		const label = new THREE.Mesh( labelGeometry, labelMaterial );
		root.add( label );
		label.position.y = bodyHeight * 4 / 5;
		label.position.z = bodyRadiusTop * 1.01;

		// if units are meters then 0.01 here makes size
		// of the label into centimeters.
		const labelBaseScale = 0.01;
		label.scale.x = canvas.width * labelBaseScale;
		label.scale.y = canvas.height * labelBaseScale;

		scene.add( root );
		return root;

	}

	makePerson( - 3, 150, 32, 'Purple People Eater', 'purple' );
	makePerson( - 0, 150, 32, 'Green Machine', 'green' );
	makePerson( + 3, 150, 32, 'Red Menace', 'red' );

	function resizeRendererToDisplaySize( renderer ) {

		const canvas = renderer.domElement;
		const width = canvas.clientWidth;
		const height = canvas.clientHeight;
		const needResize = canvas.width !== width || canvas.height !== height;
		if ( needResize ) {

			renderer.setSize( width, height, false );

		}

		return needResize;

	}

	function render() {

		if ( resizeRendererToDisplaySize( renderer ) ) {

			const canvas = renderer.domElement;
			camera.aspect = canvas.clientWidth / canvas.clientHeight;
			camera.updateProjectionMatrix();

		}

		renderer.render( scene, camera );

		requestAnimationFrame( render );

	}

	requestAnimationFrame( render );

}

main();
</script>
</html>