// Three.js physics World using ammo.js 

// Port of "ammo / instancing" from Three.js examples
// https://threejs.org/examples/?q=ammo#physics_ammo_instancing


			let camera, scene, renderer;
			let physics, position;

			let boxes, spheres;

			init();


	async function init()
	{
				physics = await AmmoPhysics();
				position = new THREE.Vector3();

				camera = new THREE.PerspectiveCamera( 50, window.innerWidth / window.innerHeight, 0.1, 100 );
				camera.position.set( - 1, 1.5, 2 );
				camera.lookAt( 0, 0.5, 0 );

				scene = new THREE.Scene();
				scene.background = new THREE.Color( 0x666666 );

				const hemiLight = new THREE.HemisphereLight();
				hemiLight.intensity = 0.35;
				scene.add( hemiLight );

				const dirLight = new THREE.DirectionalLight();
				dirLight.position.set( 5, 5, 5 );
				dirLight.castShadow = true;
				dirLight.shadow.camera.zoom = 2;
				scene.add( dirLight );

				const floor = new THREE.Mesh (
					 new THREE.BoxGeometry( 10, 5, 10 ),
					 new THREE.ShadowMaterial( { color: 0x111111 } )
				    );
				    
				floor.position.y = - 2.5;
				floor.receiveShadow = true;
				scene.add( floor );
				physics.addMesh( floor );


				const material = new THREE.MeshLambertMaterial();
				const matrix = new THREE.Matrix4();
				const color = new THREE.Color();


				// Boxes

				const geometryBox = new THREE.BoxGeometry( 0.1, 0.1, 0.1 );
				boxes = new THREE.InstancedMesh( geometryBox, material, 100 );
				boxes.castShadow = true;
				boxes.receiveShadow = true;
				scene.add( boxes );

				for ( let i = 0; i < boxes.count; i ++ ) 
				{
					matrix.setPosition( Math.random() - 0.5, Math.random() * 2, Math.random() - 0.5 );
					boxes.setMatrixAt( i, matrix );
					boxes.setColorAt( i, color.setHex( 0xffffff * Math.random() ) );
				}

				physics.addMesh( boxes, 1 );


				// Spheres

				const geometrySphere = new THREE.IcosahedronGeometry( 0.075, 3 );
				spheres = new THREE.InstancedMesh( geometrySphere, material, 100 );
				spheres.castShadow = true;
				spheres.receiveShadow = true;
				scene.add( spheres );

				for ( let i = 0; i < spheres.count; i ++ ) 
				{
					matrix.setPosition( Math.random() - 0.5, Math.random() * 2, Math.random() - 0.5 );
					spheres.setMatrixAt( i, matrix );
					spheres.setColorAt( i, color.setHex( 0xffffff * Math.random() ) );
				}

				physics.addMesh( spheres, 1 );

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

				animate();
	}



	function animate() 
	{
				requestAnimationFrame( animate );

				let index = Math.floor( Math.random() * boxes.count );

				position.set( 0, Math.random() + 1, 0 );
				physics.setMeshPosition( boxes, position, index );

				index = Math.floor( Math.random() * spheres.count );

				position.set( 0, Math.random() + 1, 0 );
				physics.setMeshPosition( spheres, position, index );

				renderer.render( scene, camera );
	}