examples/webgl_multiple_scenes_comparison.html

<!DOCTYPE html>
<html lang="en">
	<head>
		<title>three.js webgl - scene - multiple - compare</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<style>
			body {
				margin: 0px;
				overflow: hidden;
				text-align: center;
			}

			#info {
				color: #fff;
				position: absolute;
				top: 10px;
				width: 100%;
				z-index: 2;
			}

			.container {
				position: absolute;
				width: 100%;
				height: 100%;
			}

			.slider {
				position: absolute;
				cursor: ew-resize;

				width: 40px;
				height: 40px;
				background-color: #2196F3;
				opacity: 0.7;
				border-radius: 50%;

				top: calc(50% - 20px);
				left: calc(50% - 20px);

			}
		</style>
	</head>

	<body>

		<div id="info">
			<a href="http://threejs.org" target="_blank" rel="noopener">three.js</a> - multiple scenes comparison<br />
		</div>

		<div class="container">
			<div class="slider"></div>
		</div>

		<script src="../build/three.js"></script>

		<script src="js/WebGL.js"></script>
		<script src="js/libs/stats.min.js"></script>
		<script src="js/controls/OrbitControls.js"></script>

		<script>

			var container, camera, renderer, controls;
			var sceneL, sceneR;

			var sliderPos = window.innerWidth / 2;
			var sliderMoved = false;

			function init() {

				container = document.querySelector( '.container' );

				sceneL = new THREE.Scene();
				sceneL.background = new THREE.Color( 0xff00ff );

				sceneR = new THREE.Scene();
				sceneR.background = new THREE.Color( 0x8FBCD4 );

				camera = new THREE.PerspectiveCamera( 35, container.clientWidth / container.clientHeight, 0.1, 10 );
				camera.position.set( 2, 4, 7 );

				controls = new THREE.OrbitControls( camera, container );

				initMeshes();
				initLights();

				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setSize( container.clientWidth, container.clientHeight );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setScissorTest( true );

				container.appendChild( renderer.domElement );

				renderer.setAnimationLoop( function () {

					render();

				} );

				initComparisons();

			}

			function initMeshes() {

				var geoB = new THREE.BoxBufferGeometry( 2, 2, 2 );
				var matB = new THREE.MeshStandardMaterial( { color: 0x0000ff } );
				var meshB = new THREE.Mesh( geoB, matB );
				sceneL.add( meshB );

				var geoA = new THREE.IcosahedronBufferGeometry( 1, 0 );
				var matA = new THREE.MeshStandardMaterial( { color: 0xff0000 } );
				var meshA = new THREE.Mesh( geoA, matA );
				sceneR.add( meshA );

			}

			function initLights() {

				var light1 = new THREE.DirectionalLight();
				light1.position.set( 20, 20, 20 );
				sceneL.add( light1 );
				sceneR.add( light1.clone() );

				var light2 = new THREE.DirectionalLight();
				light2.position.set( - 20, 20, 20 );
				sceneL.add( light2 );
				sceneR.add( light2.clone() );

			}

			function render() {

				renderer.setScissor( 0, 0, sliderPos, window.innerHeight );
				renderer.render( sceneL, camera );

				renderer.setScissor( sliderPos, 0, window.innerWidth, window.innerHeight );
				renderer.render( sceneR, camera );

			}

			function onWindowResize() {

				camera.aspect = container.clientWidth / container.clientHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( container.clientWidth, container.clientHeight );

				if ( ! sliderMoved ) sliderPos = window.innerWidth / 2;

			}

			window.addEventListener( 'resize', onWindowResize );

			function initComparisons() {

				var slider = document.querySelector( '.slider' );

				var clicked = false;

				function slideReady() {

					clicked = true;
					controls.enabled = false;

				}

				function slideFinish() {

					clicked = false;
					controls.enabled = true;

				}

				function slideMove( e ) {

					if ( ! clicked ) return false;

					sliderMoved = true;

					sliderPos = e.pageX || e.touches[ 0 ].pageX;

					//prevent the slider from being positioned outside the window bounds
					if ( sliderPos < 0 ) sliderPos = 0;
					if ( sliderPos > window.innerWidth ) sliderPos = window.innerWidth;

					slider.style.left = sliderPos - ( slider.offsetWidth / 2 ) + "px";

				}

				slider.addEventListener( 'mousedown', slideReady );
				slider.addEventListener( 'touchstart', slideReady );

				window.addEventListener( 'mouseup', slideFinish );
				window.addEventListener( 'touchend', slideFinish );

				window.addEventListener( 'mousemove', slideMove );
				window.addEventListener( 'touchmove', slideMove );

			}

			init();

		</script>

	</body>

</html>