done_webgl_buffergeometry_drawcalls.html

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	<head>
		<title>three.js webgl - buffergeometry - lines drawcalls</title>
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			body {
				color: #cccccc;
				font-family:Monospace;
				font-size:13px;
				text-align:center;

				background-color: #000000;
				margin: 0px;
				overflow: hidden;
			}

			#info {
				position: absolute;
				top: 0px; width: 100%;
				padding: 5px;
			}

			a {
				color: #0080ff;
			}

		</style>
	</head>
	<body>

		<div id="container"></div>
		<div id="info">
			<a href="http://threejs.org" target="_blank" rel="noopener">three.js</a> webgl - buffergeometry drawcalls - by <a href="https://twitter.com/fernandojsg">fernandojsg</a>
		</div>

		<script src="js/libs/dat.gui.min.js"></script>
		<script src="../build/three.js"></script>
		<script src="js/controls/OrbitControls.js"></script>
		<script src="js/libs/stats.min.js"></script>

		<script>

			var group;
			var container, controls, stats;
			var particlesData = [];
			var camera, scene, renderer;
			var positions, colors;
			var particles;
			var pointCloud;
			var particlePositions;
			var linesMesh;

			var maxParticleCount = 1000;
			var particleCount = 500;
			var r = 800;
			var rHalf = r / 2;

			var effectController = {
				showDots: true,
				showLines: true,
				minDistance: 150,
				limitConnections: false,
				maxConnections: 20,
				particleCount: 500
			};

			init();
			animate();

			function initGUI() {

				var gui = new dat.GUI();

				gui.add( effectController, "showDots" ).onChange( function( value ) { pointCloud.visible = value; } );
				gui.add( effectController, "showLines" ).onChange( function( value ) { linesMesh.visible = value; } );
				gui.add( effectController, "minDistance", 10, 300 );
				gui.add( effectController, "limitConnections" );
				gui.add( effectController, "maxConnections", 0, 30, 1 );
				gui.add( effectController, "particleCount", 0, maxParticleCount, 1 ).onChange( function( value ) {

					particleCount = parseInt( value );
					particles.setDrawRange( 0, particleCount );

				});

			}

			function init() {

				initGUI();

				container = document.getElementById( 'container' );

				//

				camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 4000 );
				camera.position.z = 1750;

				controls = new THREE.OrbitControls( camera, container );//can use mouse to drag
                

				scene = new THREE.Scene();


				group = new THREE.Group();
				scene.add( group );//group things like AI

				var helper = new THREE.BoxHelper( new THREE.Mesh( new THREE.BoxGeometry( r, r, r ) ) );
				helper.material.color.setHex( 0x080808 );
				helper.material.blending = THREE.AdditiveBlending;
				helper.material.transparent = true;
				group.add( helper );//add helper, the outside cube

				var segments = maxParticleCount * maxParticleCount;

				positions = new Float32Array( segments * 3 );
				colors = new Float32Array( segments * 3 );

				var pMaterial = new THREE.PointsMaterial( {
					color: 0xFFFFFF,
					size: 3,
					blending: THREE.AdditiveBlending,
					transparent: true,
					sizeAttenuation: false//far points smaller
				} );

                //create all the particles
				particles = new THREE.BufferGeometry();
				particlePositions = new Float32Array( maxParticleCount * 3 );

                
                //get all the particles with its position
				for ( var i = 0; i < maxParticleCount; i++ ) {

					var x = Math.random() * r - r / 2;
					var y = Math.random() * r - r / 2;
					var z = Math.random() * r - r / 2;

					particlePositions[ i * 3     ] = x;
					particlePositions[ i * 3 + 1 ] = y;
					particlePositions[ i * 3 + 2 ] = z;

					// add more info to the particles
					particlesData.push( {
						velocity: new THREE.Vector3( -1 + Math.random() * 2, -1 + Math.random() * 2,  -1 + Math.random() * 2 ),
						numConnections: 0
					} );

				}

				particles.setDrawRange( 0, particleCount );
				particles.addAttribute( 'position', new THREE.BufferAttribute( particlePositions, 3 ).setDynamic( true ) );//remind GPU this value will be used often

				// create the particle system
				pointCloud = new THREE.Points( particles, pMaterial );
				group.add( pointCloud );

                //create lines
				var geometry = new THREE.BufferGeometry();

				geometry.addAttribute( 'position', new THREE.BufferAttribute( positions, 3 ).setDynamic( true ) );
				geometry.addAttribute( 'color', new THREE.BufferAttribute( colors, 3 ).setDynamic( true ) );

				geometry.computeBoundingBox();

				geometry.setDrawRange( 100, 10000 );

				var material = new THREE.LineBasicMaterial( {
					vertexColors: THREE.VertexColors,
					blending: THREE.AdditiveBlending,
					transparent: true
				} );

				linesMesh = new THREE.LineSegments( geometry, material );
				group.add( linesMesh );

				//

				renderer = new THREE.WebGLRenderer( { antialias: true } );//more smooth
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );

                //render more smooth
				renderer.gammaInput = true;
				renderer.gammaOutput = true;

				container.appendChild( renderer.domElement );

				//

				stats = new Stats();
				container.appendChild( stats.dom );

				window.addEventListener( 'resize', onWindowResize, false );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

			function animate() {

				var vertexpos = 0;
				var colorpos = 0;
				var numConnected = 0;

                
                //initialize all the points when start
				for ( var i = 0; i < particleCount; i++ )
					particlesData[ i ].numConnections = 0;

                //let the particle moves 
				for ( var i = 0; i < particleCount; i++ ) {

					// get the particle
					var particleData = particlesData[i];

					particlePositions[ i * 3     ] += particleData.velocity.x;
					particlePositions[ i * 3 + 1 ] += particleData.velocity.y;
					particlePositions[ i * 3 + 2 ] += particleData.velocity.z;

                    //hit the wall, then return
					if ( particlePositions[ i * 3 + 1 ] < -rHalf || particlePositions[ i * 3 + 1 ] > rHalf )
						particleData.velocity.y = -particleData.velocity.y;

					if ( particlePositions[ i * 3 ] < -rHalf || particlePositions[ i * 3 ] > rHalf )
						particleData.velocity.x = -particleData.velocity.x;

					if ( particlePositions[ i * 3 + 2 ] < -rHalf || particlePositions[ i * 3 + 2 ] > rHalf )
						particleData.velocity.z = -particleData.velocity.z;

                    //connection come to the limit then did not connect 
					if ( effectController.limitConnections && particleData.numConnections >= effectController.maxConnections )
						continue;

					// Check collision
                    // Check every other points to determine whether show the line 
					for ( var j = i + 1; j < particleCount; j++ ) {

						var particleDataB = particlesData[ j ];
						if ( effectController.limitConnections && particleDataB.numConnections >= effectController.maxConnections )
							continue;

						var dx = particlePositions[ i * 3     ] - particlePositions[ j * 3     ];
						var dy = particlePositions[ i * 3 + 1 ] - particlePositions[ j * 3 + 1 ];
						var dz = particlePositions[ i * 3 + 2 ] - particlePositions[ j * 3 + 2 ];
						var dist = Math.sqrt( dx * dx + dy * dy + dz * dz );

						if ( dist < effectController.minDistance ) {

							particleData.numConnections++;
							particleDataB.numConnections++;

							var alpha = 1.0 - dist / effectController.minDistance;
                            
                            //update the position of lines
							positions[ vertexpos++ ] = particlePositions[ i * 3     ];
							positions[ vertexpos++ ] = particlePositions[ i * 3 + 1 ];
							positions[ vertexpos++ ] = particlePositions[ i * 3 + 2 ];

							positions[ vertexpos++ ] = particlePositions[ j * 3     ];
							positions[ vertexpos++ ] = particlePositions[ j * 3 + 1 ];
							positions[ vertexpos++ ] = particlePositions[ j * 3 + 2 ];

							colors[ colorpos++ ] = alpha;
							colors[ colorpos++ ] = alpha;
							colors[ colorpos++ ] = alpha;

							colors[ colorpos++ ] = alpha;
							colors[ colorpos++ ] = alpha;
							colors[ colorpos++ ] = alpha;

							numConnected++;
						}
					}
				}


				linesMesh.geometry.setDrawRange( 0, numConnected * 2 );
				linesMesh.geometry.attributes.position.needsUpdate = true;
				linesMesh.geometry.attributes.color.needsUpdate = true;

				pointCloud.geometry.attributes.position.needsUpdate = true;

				requestAnimationFrame( animate );

				stats.update();
				render();

			}

			function render() {

				var time = Date.now() * 0.001;

				group.rotation.y = time * 0.1;
				renderer.render( scene, camera );

			}

		</script>
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</html>