//过直线外一点画垂线function drawVerticalLine(point, line){    //画辅助线-start    var color = ‘DarkRed‘; //垂线的颜色    var color2 = "#ccc"; //其它辅助线的颜色    drawPoint({        pw:2,ph:2,color:‘DarkRed‘,point: line[0]    });    drawPoint({        pw:2,ph:2,color:‘DarkRed‘,point: line[1]    });    drawLine(point, line[0], {color: color2});    drawLine(point, line[1], {color: color2});    //画辅助线-end        drawPoint({        pw:2,ph:2,color:‘DarkRed‘,point: point    });            var v_1_0 = line[1][1]-line[0][1];     var h_1_0 = line[1][0]-line[0][0];     var c_square = Math.pow(v_1_0,2) + Math.pow(h_1_0,2);     var c = Math.sqrt(c_square); //计算直线上两点之间的距离        var a_b_slope = 0;    var hasSlope = true;    if(v_1_0 == 0){        hasSlope = false;    }    a_b_slope = v_1_0/h_1_0; //直线的斜率        var point_pos = 1; //定义point与直线的位置关系    //当直线的斜率大于0时，如果点在直线上方，point_pos = 1，如果点在直线下方，point_pos = 3    //当直线的斜率小于0时，如果点在直线上方，point_pos = 2，如果点在直线下方，point_pos = 4    if(hasSlope){        var a_b_intercept = line[1][1]-a_b_slope*line[1][0];        var p_intercept = point[1]-a_b_slope*point[0];        if(a_b_slope >= 0){            if(p_intercept > a_b_intercept){                point_pos = 3;            }else{                point_pos = 1;            }        }else{            if(p_intercept < a_b_intercept){                point_pos = 2;            }else{                point_pos = 4;            }        }    }    //A为直线与水平线的夹角（锐角）    var sinA = Math.abs(v_1_0)/c; //sinA    var cosA = Math.abs(h_1_0)/c; //cosA    //C为垂线在顺时针方向上与水平线的夹角    var sinC = 0;    var cosC = 0;    //D为过point与line的平行线与水平线的夹角    var sinD = 0;    var cosD = 0;    switch(point_pos){    case 1:        sinC = cosA;        cosC = -sinA;        sinD = -cosC;        cosD = sinC;        break;    case 2:        sinC = cosA;        cosC = sinA;        sinD = cosC;        cosD = -sinC;        break;    case 3:        sinC = -cosA;        cosC = sinA;        sinD = cosC;        cosD = -sinC;        break;    case 4:        sinC = -cosA;        cosC = -sinA;        sinD = -cosC;        cosD = sinC;        break;        default:    }    //过point画line的平行线    drawLine(point, [point[0]+c*cosD, point[1]+c*sinD], {color: ‘Red‘});    drawLine(point, [point[0]+c*(-cosD), point[1]+c*(-sinD)], {color: ‘Red‘});        var point_v_1 = point[1]-line[1][1];    var point_h_1 = point[0]-line[1][0];    var point_dist_1 = Math.sqrt(Math.pow(point_v_1,2)+Math.pow(point_h_1,2)); //point到line上一点的距离    var point_v_0 = point[1]-line[0][1];    var point_h_0 = point[0]-line[0][0];    var point_dist_0 = Math.sqrt(Math.pow(point_v_0,2)+Math.pow(point_h_0,2)); //point到line上另外一点的距离    var s = (c+point_dist_1+point_dist_0)/2;    var area = Math.sqrt(s*(s-c)*(s-point_dist_0)*(s-point_dist_1)); //以point、line[0]和line[1]为顶点的三角形的面积    var h = 2*area/c; //三角形的高        var vpoint = [point[0]+h*cosC, point[1]+h*sinC]; //垂点    drawLine(point, vpoint); //画垂线}