manual/examples/multiple-scenes-copy-canvas.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 - Multiple Scenes - Copy</title>
    <style>
    canvas {
      width: 100%;
      height: 100%;
      display: block;
    }
    *[data-diagram] {
      display: inline-block;
      width: 5em;
      height: 3em;
    }
    .left {
      float: left;
      margin-right: .25em;
    }
    .right {
      float: right;
      margin-left: .25em;
    }
    p {
      margin: 1em auto;
      max-width: 500px;
      font-size: xx-large;
    }
    </style>
  </head>
  <body>
    <p>
      <span data-diagram="box" class="left"></span>
      I love boxes. Presents come in boxes.
      When I find a new box I'm always excited to find out what's inside.
    </p>
    <p>
      <span data-diagram="pyramid" class="right"></span>
      When I was a kid I dreamed of going on an expedition inside a pyramid
      and finding a undiscovered tomb full of mummies and treasure.
    </p>
  </body>
<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js",
    "three/addons/": "../../examples/jsm/"
  }
}
</script>

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

function main() {

	const canvas = document.createElement( 'canvas' );
	const renderer = new THREE.WebGLRenderer( { antialias: true, canvas, alpha: true } );

	renderer.setScissorTest( true );

	const sceneElements = [];
	function addScene( elem, fn ) {

		const ctx = document.createElement( 'canvas' ).getContext( '2d' );
		elem.appendChild( ctx.canvas );
		sceneElements.push( { elem, ctx, fn } );

	}

	function makeScene( elem ) {

		const scene = new THREE.Scene();

		const fov = 45;
		const aspect = 2; // the canvas default
		const near = 0.1;
		const far = 5;
		const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
		camera.position.set( 0, 1, 2 );
		camera.lookAt( 0, 0, 0 );
		scene.add( camera );

		const controls = new TrackballControls( camera, elem );
		controls.noZoom = true;
		controls.noPan = true;

		{

			const color = 0xFFFFFF;
			const intensity = 3;
			const light = new THREE.DirectionalLight( color, intensity );
			light.position.set( - 1, 2, 4 );
			camera.add( light );

		}

		return { scene, camera, controls };

	}

	const sceneInitFunctionsByName = {
		'box': ( elem ) => {

			const { scene, camera, controls } = makeScene( elem );
			const geometry = new THREE.BoxGeometry( 1, 1, 1 );
			const material = new THREE.MeshPhongMaterial( { color: 'red' } );
			const mesh = new THREE.Mesh( geometry, material );
			scene.add( mesh );
			return ( time, rect ) => {

				mesh.rotation.y = time * .1;
				camera.aspect = rect.width / rect.height;
				camera.updateProjectionMatrix();
				controls.handleResize();
				controls.update();
				renderer.render( scene, camera );

			};

		},
		'pyramid': ( elem ) => {

			const { scene, camera, controls } = makeScene( elem );
			const radius = .8;
			const widthSegments = 4;
			const heightSegments = 2;
			const geometry = new THREE.SphereGeometry( radius, widthSegments, heightSegments );
			const material = new THREE.MeshPhongMaterial( {
				color: 'blue',
				flatShading: true,
			} );
			const mesh = new THREE.Mesh( geometry, material );
			scene.add( mesh );
			return ( time, rect ) => {

				mesh.rotation.y = time * .1;
				camera.aspect = rect.width / rect.height;
				camera.updateProjectionMatrix();
				controls.handleResize();
				controls.update();
				renderer.render( scene, camera );

			};

		},
	};

	document.querySelectorAll( '[data-diagram]' ).forEach( ( elem ) => {

		const sceneName = elem.dataset.diagram;
		const sceneInitFunction = sceneInitFunctionsByName[ sceneName ];
		const sceneRenderFunction = sceneInitFunction( elem );
		addScene( elem, sceneRenderFunction );

	} );

	function render( time ) {

		time *= 0.001;

		for ( const { elem, fn, ctx } of sceneElements ) {

			// get the viewport relative position of this element
			const rect = elem.getBoundingClientRect();
			const { left, right, top, bottom, width, height } = rect;
			const rendererCanvas = renderer.domElement;

			const isOffscreen =
          bottom < 0 ||
          top > window.innerHeight ||
          right < 0 ||
          left > window.innerWidth;

			if ( ! isOffscreen ) {

				// make sure the renderer's canvas is big enough
				if ( rendererCanvas.width < width || rendererCanvas.height < height ) {

					renderer.setSize( width, height, false );

				}

				// make sure the canvas for this area is the same size as the area
				if ( ctx.canvas.width !== width || ctx.canvas.height !== height ) {

					ctx.canvas.width = width;
					ctx.canvas.height = height;

				}

				renderer.setScissor( 0, 0, width, height );
				renderer.setViewport( 0, 0, width, height );

				fn( time, rect );

				// copy the rendered scene to this element's canvas
				ctx.globalCompositeOperation = 'copy';
				ctx.drawImage(
					rendererCanvas,
					0, rendererCanvas.height - height, width, height, // src rect
					0, 0, width, height ); // dst rect

			}

		}

		requestAnimationFrame( render );

	}

	requestAnimationFrame( render );

}

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