/*
 *緩動(dòng)效果
 *初始坐標(biāo)，目標(biāo)坐標(biāo)，當(dāng)前的步長，總的步長
 *@param{BMap.Pixel} initPos 初始平面坐標(biāo)
 *@parm{BMap.Pixel} targetPos 目標(biāo)平面坐標(biāo)
 *@param{number} 當(dāng)前幀數(shù)
 *@param {number} count 總幀數(shù)
 */
 this.linear = function (initPos, targetPos, currentCount, count) {
  var b = initPos, c = targetPos - initPos, t = currentCount,
  d = count;
  return c * t / d + b;
 }
　　 var x = effect(_prvePoint.x, _newPoint.x, currentCount, count),
  y = effect(_prvePoint.y, _newPoint.y, currentCount, count);

/**
 *小車移動(dòng)
 *@param {Point} prvePoint 開始坐標(biāo)(PrvePoint)
 *@param {Point} newPoint 目標(biāo)點(diǎn)坐標(biāo)
 *@param {Function} 動(dòng)畫效果
 *@return 無返回值
 */
 this.Move = function (prvePoint, newPoint, effect, setRotation) {
  var me = this,
    //當(dāng)前幀數(shù)
    currentCount = 0,
    //初始坐標(biāo)
    _prvePoint = me._projection.lngLatToPoint(prvePoint),//將球面坐標(biāo)轉(zhuǎn)換為平面坐標(biāo)
    //獲取結(jié)束點(diǎn)的(x,y)坐標(biāo)
    _newPoint = me._projection.lngLatToPoint(newPoint),
    //兩點(diǎn)之間要循環(huán)定位的次數(shù)
    count = me._runTime / me._intervalTimer;
    //兩點(diǎn)之間勻速移動(dòng)
    me._intervalFlag = setInterval(function () {
     //兩點(diǎn)之間當(dāng)前幀數(shù)大于總幀數(shù)的時(shí)候，則說明已經(jīng)完成移動(dòng)
     if (currentCount >= count) {
     clearInterval(me._intervalFlag);
     } else {
    //動(dòng)畫移動(dòng)
    currentCount++;//計(jì)數(shù)
      var x = effect(_prvePoint.x, _newPoint.x, currentCount, count),
       y = effect(_prvePoint.y, _newPoint.y, currentCount, count);
      //根據(jù)平面坐標(biāo)轉(zhuǎn)化為球面坐標(biāo)
    var pos = map.getMapType().getProjection().pointToLngLat(new BMap.Pixel(x, y));
    //設(shè)置marker角度(兩點(diǎn)之間的距離車的角度保持一致)
     if (currentCount == 1) {
      //轉(zhuǎn)換角度                     setRotation(prvePoint,newPoint, me._em);
     }
      //正在移動(dòng)
    me._em._newPointMark.setPosition(pos);
   }
    }, me._intervalTimer);
    me._em._prvePoint = newPoint;
 }

/**
 *在每個(gè)點(diǎn)的真實(shí)步驟中設(shè)置小車轉(zhuǎn)動(dòng)的角度
 *@param{BMap.Point} curPos 起點(diǎn)
  *@param{BMap.Point} targetPos 終點(diǎn)
 */
  this.setRotation = function (curPos, targetPos, em)
  {
   var me = this;
   var deg = 0;
   curPos = map.pointToPixel(curPos);
   targetPos = map.pointToPixel(targetPos);
   if (targetPos.x != curPos.x) {
    var tan = (targetPos.y - curPos.y) / (targetPos.x - curPos.x),
    atan = Math.atan(tan);
    deg = atan * 360 / (2 * Math.PI);
    if (targetPos.x < curPos.x) {
     deg = -deg + 90 + 90;
    } else {
     deg = -deg;
    }
    em._newPointMark.setRotation(-deg);
   } else {
    var disy = targetPos.y - curPos.y;
    var bias = 0;
    if (disy > 0)
     bias = -1
    else
     bias = 1
    em._newPointMark.setRotation(-bias * 90);
   }
   return;
  }