closestPoint.js

//line -> geometria do rua
//point-> geometria do ponto

exports.closestPoint = function(line, point){
//function closestPoint(line, point){

    //tratar a string da geometria linha
    var geomLine = line.substr(line.indexOf("(")+2);
    geomLine = geomLine.substr(0,geomLine.indexOf(")"));

    //tratar a string da geometria ponto
    var geomPoint = point.substr(point.indexOf("(")+1);
    geomPoint = geomPoint.substr(0,geomPoint.indexOf(")"));

    //variaveis globais
    var distances = [];
    var distTotal = 0;
    var minDistance = 1000;

    //divide o endereço em x y
    var coordinates = geomPoint.split(' ');

    //divide a rua em grupo de pontos
    var pointsLine = geomLine.split(',');
     
    //loop para somar as distancias
    for (var i = 1; i < pointsLine.length; i++) {

        //insere as distancias no array distances
        distances[i] = getDistance(pointsLine[(i-1)].split(' ')[0], pointsLine[(i-1)].split(' ')[1], pointsLine[(i)].split(' ')[0], pointsLine[(i)].split(' ')[1]);
        distTotal = distTotal + distances[i];

        //descobre onde se encontre o endereço buscados
        if (getDistance(geomPoint.split(' ')[0], geomPoint.split(' ')[1], pointsLine[(i-1)].split(' ')[0], pointsLine[(i-1)].split(' ')[1]) < minDistance) {
        	minDistance = getDistance(geomPoint.split(' ')[0], geomPoint.split(' ')[1], pointsLine[(i-1)].split(' ')[0], pointsLine[(i-1)].split(' ')[1])
        	index = i;
        }
    }

    //declara variavel P
    var P = [];
    P.x = geomPoint.split(' ')[0];
    P.y = geomPoint.split(' ')[1];

    //declara variavel A
    var A = [];
    A.x = pointsLine[(index-1)].split(' ')[0];
    A.y = pointsLine[(index-1)].split(' ')[1];

    
    //declara variavel B
    var B = [];
    B.x = pointsLine[(index)].split(' ')[0];
    B.y = pointsLine[(index)].split(' ')[1];
    
    //declara variavel AP
    var AP = [];
    AP.x = P.x - A.x;
    AP.y = P.y - A.y;

    //declara variavel AB    
    var AB = [];
    AB.x = B.x - A.x;
    AB.y = B.y - A.y;

    //declara variavel ab2, ap_ab e t
    var ab2 = AB.x*AB.x + AB.y*AB.y;
    var ap_ab = AP.x*AB.x + AP.y*AB.y;
    var t = ap_ab / ab2;
    
    //calcula closestPoint usando primeiro ponto mais a distancia total vezes t
    closestPoint.x = parseFloat(A.x) + parseFloat(AB.x) * parseFloat(t);
    closestPoint.y = parseFloat(A.y) + parseFloat(AB.y) * parseFloat(t);

    //alert("POINT("+closestPoint.x +" "+closestPoint.y+")");
    return("POINT("+closestPoint.x +" "+closestPoint.y+")");

}

//FUNÇÕES AUXILIARES
var getDistance = function(x1, y1, x2, y2){
    return Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
}