/// <summary>抽稀处理，对密集的点抽稀，保持点的均匀分布。</summary>

/// <param name="points" type="Array">待抽稀的数组  features Array</param>

/// <param name="tolerance" type="Float">取样临界值</param>

/// <param name="indicator" type="string">关键属性</param>

var simplifyMutiPoints = {

    // dis: 1000,

    // degToMeter: Math.PI * 6378137 / 180.0, //6378137赤道半径，一度对应赤道上的一米

    // buf: parseInt(this.dis * 1.0e7 / degToMeter), //1公里对应多少度

    getProcessPoints: function(points, tolerance, indicator) {

        if (points.length < 3) return points; //小于3个点时不抽稀，因为1个或2个点无法进行抽稀

        var IndexsToReduce = this.reduce(points, tolerance, indicator); //抽稀 //保存需要点下标的数组

        var resultPoints = []; //返回的点数组

        for (var i = 0; i < points.length; i++) {

            if (IndexsToReduce.indexOf(i) < 0) {

                resultPoints.push(points[i]);

            }

        }

        return resultPoints;

    },

    reduce: function(points, tolerance, indicator) { //遍历抽稀，删除相同权重的点

        // var IndexsToKeep = [];

        var IndexsToReduce = [];

        for (var i = 0; i < points.length; i++) {

            var k = i + 1;

            if (IndexsToReduce.indexOf(i) >= 0) { //如果是已删除的点，跳出

                continue;

            }

            var p1 = points[i];

            while (k < points.length) {

                var p2 = points[k];

                var ToReduce = this.CheckPointEqualInBuffer(p1, p2, tolerance, indicator);

                if (ToReduce) {

                    IndexsToReduce.push(k);

                }

                k++;

            }

        }

        return IndexsToReduce;

    },

    //判断在抽稀中是否等值（依据缓冲范围以及关键属性）

    CheckPointEqualInBuffer: function(point1, point2, buffer /*缓冲相等*/ , indicator /*属性相等*/ ) {

      var x1=point1.geometry.coordinates[0],

      y1=point1.geometry.coordinates[1],

      x2=point2.geometry.coordinates[0],

      y2=point2.geometry.coordinates[1];

        var inbuffer = (Math.abs(x1 - x2) <= buffer && Math.abs(y1 - y2) <= buffer);

        var iszEqual = true;

        if (indicator) {

            iszEqual = point1.properties[indicator] == point2.properties[indicator];

        }

        return inbuffer && iszEqual;

    }

};