//是否开启光照
viewer.shadows=true;//光照分析时候一定要设置true

//光照阴影位置和当前的时间有关
//设置当前时间可以改变阴影的位置
var julianDay =computes(new Date());
//当天已经过去的时间单位s
var julianSecound=hour*60*60+minute*60+secound;//hour当前时，minute当前分，secound当前秒
viewer.clock.currentTime= new LSGlobe.JulianDate(julianDay,julianSecound);

//当前时间转换为朱莉安时间
function computes(now){
    var month = now.getUTCMonth() + 1;
    var day = now.getUTCDate();
    var year = now.getUTCFullYear()
    var y = eval(year);
    var m = eval(month);
    var d = eval(day);
    var extra = 100.0*y + m - 190002.5;
    var rjd = 367.0*y;
    rjd -= Math.floor(7.0*(y+Math.floor((m+9.0)/12.0))/4.0);
    rjd += Math.floor(275.0*m/9.0);
    rjd += d;
    rjd += 1721013.5;
    rjd -= 0.5*extra/Math.abs(extra);
    rjd += 0.5;
    return rjd;
}