three.js/examples/jsm/renderers/CSS3DRenderer.js

import {
	Matrix4,
	Object3D
} from '../../../build/three.module.js';

/**
 * Based on http://www.emagix.net/academic/mscs-project/item/camera-sync-with-css3-and-webgl-threejs
 */

class CSS3DObject extends Object3D {

	constructor( element ) {

		super();

		this.element = element || document.createElement( 'div' );
		this.element.style.position = 'absolute';
		this.element.style.pointerEvents = 'auto';

		this.addEventListener( 'removed', function () {

			this.traverse( function ( object ) {

				if ( object.element instanceof Element && object.element.parentNode !== null ) {

					object.element.parentNode.removeChild( object.element );

				}

			} );

		} );

	}

	copy( source, recursive ) {

		super.copy( source, recursive );

		this.element = source.element.cloneNode( true );

		return this;

	}

}

CSS3DObject.prototype.isCSS3DObject = true;

class CSS3DSprite extends CSS3DObject {

	constructor( element ) {

		super( element );

	}

}

CSS3DSprite.prototype.isCSS3DSprite = true;

//

const _matrix = new Matrix4();

class CSS3DRenderer {

	constructor() {

		const _this = this;

		let _width, _height;
		let _widthHalf, _heightHalf;

		const cache = {
			camera: { fov: 0, style: '' },
			objects: new WeakMap()
		};

		const domElement = document.createElement( 'div' );
		domElement.style.overflow = 'hidden';

		this.domElement = domElement;

		const cameraElement = document.createElement( 'div' );

		cameraElement.style.transformStyle = 'preserve-3d';
		cameraElement.style.pointerEvents = 'none';

		domElement.appendChild( cameraElement );

		this.getSize = function () {

			return {
				width: _width,
				height: _height
			};

		};

		this.render = function ( scene, camera ) {

			const fov = camera.projectionMatrix.elements[ 5 ] * _heightHalf;

			if ( cache.camera.fov !== fov ) {

				domElement.style.perspective = camera.isPerspectiveCamera ? fov + 'px' : '';
				cache.camera.fov = fov;

			}

			if ( scene.autoUpdate === true ) scene.updateMatrixWorld();
			if ( camera.parent === null ) camera.updateMatrixWorld();

			let tx, ty;

			if ( camera.isOrthographicCamera ) {

				tx = - ( camera.right + camera.left ) / 2;
				ty = ( camera.top + camera.bottom ) / 2;

			}

			const cameraCSSMatrix = camera.isOrthographicCamera ?
				'scale(' + fov + ')' + 'translate(' + epsilon( tx ) + 'px,' + epsilon( ty ) + 'px)' + getCameraCSSMatrix( camera.matrixWorldInverse ) :
				'translateZ(' + fov + 'px)' + getCameraCSSMatrix( camera.matrixWorldInverse );

			const style = cameraCSSMatrix +
				'translate(' + _widthHalf + 'px,' + _heightHalf + 'px)';

			if ( cache.camera.style !== style ) {

				cameraElement.style.transform = style;

				cache.camera.style = style;

			}

			renderObject( scene, scene, camera, cameraCSSMatrix );

		};

		this.setSize = function ( width, height ) {

			_width = width;
			_height = height;
			_widthHalf = _width / 2;
			_heightHalf = _height / 2;

			domElement.style.width = width + 'px';
			domElement.style.height = height + 'px';

			cameraElement.style.width = width + 'px';
			cameraElement.style.height = height + 'px';

		};

		function epsilon( value ) {

			return Math.abs( value ) < 1e-10 ? 0 : value;

		}

		function getCameraCSSMatrix( matrix ) {

			const elements = matrix.elements;

			return 'matrix3d(' +
				epsilon( elements[ 0 ] ) + ',' +
				epsilon( - elements[ 1 ] ) + ',' +
				epsilon( elements[ 2 ] ) + ',' +
				epsilon( elements[ 3 ] ) + ',' +
				epsilon( elements[ 4 ] ) + ',' +
				epsilon( - elements[ 5 ] ) + ',' +
				epsilon( elements[ 6 ] ) + ',' +
				epsilon( elements[ 7 ] ) + ',' +
				epsilon( elements[ 8 ] ) + ',' +
				epsilon( - elements[ 9 ] ) + ',' +
				epsilon( elements[ 10 ] ) + ',' +
				epsilon( elements[ 11 ] ) + ',' +
				epsilon( elements[ 12 ] ) + ',' +
				epsilon( - elements[ 13 ] ) + ',' +
				epsilon( elements[ 14 ] ) + ',' +
				epsilon( elements[ 15 ] ) +
			')';

		}

		function getObjectCSSMatrix( matrix ) {

			const elements = matrix.elements;
			const matrix3d = 'matrix3d(' +
				epsilon( elements[ 0 ] ) + ',' +
				epsilon( elements[ 1 ] ) + ',' +
				epsilon( elements[ 2 ] ) + ',' +
				epsilon( elements[ 3 ] ) + ',' +
				epsilon( - elements[ 4 ] ) + ',' +
				epsilon( - elements[ 5 ] ) + ',' +
				epsilon( - elements[ 6 ] ) + ',' +
				epsilon( - elements[ 7 ] ) + ',' +
				epsilon( elements[ 8 ] ) + ',' +
				epsilon( elements[ 9 ] ) + ',' +
				epsilon( elements[ 10 ] ) + ',' +
				epsilon( elements[ 11 ] ) + ',' +
				epsilon( elements[ 12 ] ) + ',' +
				epsilon( elements[ 13 ] ) + ',' +
				epsilon( elements[ 14 ] ) + ',' +
				epsilon( elements[ 15 ] ) +
			')';

			return 'translate(-50%,-50%)' + matrix3d;

		}

		function renderObject( object, scene, camera, cameraCSSMatrix ) {

			if ( object.isCSS3DObject ) {

				object.onBeforeRender( _this, scene, camera );

				let style;

				if ( object.isCSS3DSprite ) {

					// http://swiftcoder.wordpress.com/2008/11/25/constructing-a-billboard-matrix/

					_matrix.copy( camera.matrixWorldInverse );
					_matrix.transpose();
					_matrix.copyPosition( object.matrixWorld );
					_matrix.scale( object.scale );

					_matrix.elements[ 3 ] = 0;
					_matrix.elements[ 7 ] = 0;
					_matrix.elements[ 11 ] = 0;
					_matrix.elements[ 15 ] = 1;

					style = getObjectCSSMatrix( _matrix );

				} else {

					style = getObjectCSSMatrix( object.matrixWorld );

				}

				const element = object.element;
				const cachedObject = cache.objects.get( object );

				if ( cachedObject === undefined || cachedObject.style !== style ) {

					element.style.transform = style;

					const objectData = { style: style };
					cache.objects.set( object, objectData );

				}

				element.style.display = object.visible ? '' : 'none';

				if ( element.parentNode !== cameraElement ) {

					cameraElement.appendChild( element );

				}

				object.onAfterRender( _this, scene, camera );

			}

			for ( let i = 0, l = object.children.length; i < l; i ++ ) {

				renderObject( object.children[ i ], scene, camera, cameraCSSMatrix );

			}

		}

	}

}

export { CSS3DObject, CSS3DSprite, CSS3DRenderer };