openlayers学习三--画点性能

学习二中画点可能存在丢点的情况，稍微改进了一下，node.js接受数据时把数存起来，发送时一起发，html也一样

const dgram = require('dgram');
let server = dgram.createSocket('udp4');
server.bind(6000);

var pp = [];
server.on('message',function(msg,rinfo){
    const t = msg.slice(0,4);
    const b = msg.slice(4,8);
    const l = msg.slice(8,12);

    const p = new Array(4);
    p[0] = 32;
    p[0] = p[0].toString();
    p[1] = t.readFloatLE(0).toString();
    p[2] = b.readFloatLE(0).toString();
    p[3] = l.readFloatLE(0).toString();
    pp.push(p);
    //console.log(pp.toString());
})

var time = 1;
var ws = require('nodejs-websocket');
var wss = ws.createServer(conn =>{
    console.log("正在连接");
    conn.on('text',function(data){
        //console.log("收到："+data);
        while(pp.length>0){
          console.log(pp[0].toString());
          conn.send(pp[0].toString());
          pp.shift();
          
        }
        time+=1;
    })
    conn.on('close',function(){
        conn.log('closed');
    })
    conn.on('error',function(){
        conn.log('error');
    })
})

wss.listen(3000,function(){
    console.log('正在监听3000端口');
})

    ws.onmessage = function(e){
      var pp = (e.data).split(",");
      var head = parseInt(pp[0]);
      if(head==32){
        var time = parseInt(pp[1]);
        tobeDraw.push([time,lon+0.3*time,lat+0.3*time]);
        lon -=0.01;
        console.log(time);
      }
      else{
        console.log(pp);
      }
    };

    var drawPoint = function(){while(tobeDraw.length>0){
        var coord = ol.proj.transform([tobeDraw[0][1],tobeDraw[0][2]],'EPSG:4326', 'EPSG:3857');
        var feature = new ol.Feature({
          geometry: new ol.geom.Point(coord)
        });       
        vectorLayer.getSource().addFeature(feature);
        drawedpoints.push(tobeDraw[0][0]);
      }
    }

    var interID = window.setInterval(drawPoint,1000);

用定时器渲染，1hz时，cpu毫无压力，一屏幕点了