allBuildingsSTL.js

var fs = require('fs'),
    stl = require('stl'),
    poly2tri = require('poly2tri');

module.exports.allBuildingsSTL = allBuildingsSTL;

//Lat/Long and Coordinate Stuff
Number.prototype.toRadians = function () {
    return this * Math.PI / 180;
};
Number.prototype.toDegrees = function () {
    return this * 180 / Math.PI;
};

//Create Lat/Lng object
function latLon(lat, lng) {
    this.latitude = Number(lat);
    this.longitude = Number(lng);
}
//Latitude and Longitude to X,Y Coord
latLon.prototype.coordinatesTo = function (point) {
    var radius = 6371;
    var phi1 = this.latitude.toRadians(),
        lambda1 = this.longitude.toRadians(),
        phi2 = point.latitude.toRadians(),
        lambda2 = point.longitude.toRadians();
    var deltaPhi = phi2 - phi1,
        deltaLambda = lambda2 - lambda1;

    var a = Math.pow(Math.sin(deltaPhi / 2), 2) + Math.cos(phi1) * Math.cos(phi2) * Math.pow(Math.sin(deltaLambda / 2), 2);

    var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
    var d = radius * c * 1000;

    var x = Math.cos(phi1) * Math.sin(phi2) - Math.sin(phi1) * Math.cos(phi2) * Math.cos(deltaLambda),
        y = Math.sin(deltaLambda) * Math.cos(phi2);
    var theta = Math.atan2(y, x);
    var X = d * Math.sin(theta),
        Y = d * Math.cos(theta);
    return [X, Y];
}

//Coordinates from Basic Lat/lng point to Lat/Lng

latLon.prototype.destinationPoint = function (X, Y) {
    var radius = 6371;
    var brng = Math.atan(X / Y),
        dist = Math.sqrt(Math.pow(X, 2) + Math.pow(Y, 2));
    var theta = Number(brng).toRadians();
    var delta = Number(dist) / radius; // angular distance in radians

    var phi1 = this.latitude.toRadians();
    var lambda1 = this.longitude.toRadians();

    var phi2 = Math.asin(Math.sin(phi1) * Math.cos(delta) +
        Math.cos(phi1) * Math.sin(delta) * Math.cos(theta));
    var lambda2 = lambda1 + Math.atan2(Math.sin(theta) * Math.sin(delta) * Math.cos(phi1),
        Math.cos(delta) - Math.sin(phi1) * Math.sin(phi2));
    lambda2 = (lambda2 + 3 * Math.PI) % (2 * Math.PI) - Math.PI; // normalise to -180..+180º

    return new latLon(phi2.toDegrees(), lambda2.toDegrees());
}

//Create STL format

function createFacet(verts) {
    return {
        verts: verts
    }
}

function createPlane(p1, p2, h) {
    var tri1 = [[p1[0], p1[1], 0], [p2[0], p2[1], 0], [p2[0], p2[1], h]];
    var tri2 = [[p1[0], p1[1], 0], [p2[0], p2[1], h], [p1[0], p1[1], h]];
    var facets = [{
        verts: tri1
    }, {
        verts: tri2
    }];
    return facets;
}

function createSTL(points, height, buildingName) {
    //Add facets
    var facets = [];

    //Walls
    for (var i = 1; i < points.length; i++) {
        var tri = createPlane(points[i - 1], points[i], height);
        facets.push(tri[0]);
        facets.push(tri[1]);
    }
    var tri = createPlane(points[points.length - 1], points[0], height);
    facets.push(tri[0]);
    facets.push(tri[1]);

    //Top and Bottom
    var contour = [];
    points.forEach(function (point) {
        contour.push(new poly2tri.Point(point[0], point[1]));
    });
    var swctx = new poly2tri.SweepContext(contour);
    swctx.triangulate();
    var triangles = swctx.getTriangles();
    //Create Bottom Plane
    triangles.forEach(function (tri) {
        var verts = [];
        tri.points_.reverse();
        tri.points_.forEach(function (points) {
            verts.push([points.x, points.y, 0]);
        });
        facets.push(createFacet(verts));
    });

    //Create Top Plane
    triangles.forEach(function (tri) {
        var verts = [];
        tri.points_.reverse();
        tri.points_.forEach(function (points) {
            verts.push([points.x, points.y, height]);
        });
        facets.push(createFacet(verts));
    });
    var stlObj = {
        description: buildingName,
        facets: facets
    };
    var buildingSTL = stl.fromObject(stlObj);
    return buildingSTL;
    //fs.writeFileSync("stlFiles/" + buildingName + '.stl', stl.fromObject(stlObj));
}


//All Buildings STL function for Export
function allBuildingsSTL(buildings) {
    //Average Lat and Long
    var lat = 0,
        lng = 0,
        count = 0;

    buildings.forEach(function (building) {
        building.path.forEach(function (point) {
            lat += point.latitude;
            lng += point.longitude;
            count++;
        });
    });
    var centerLat = lat / count,
        centerLng = lng / count,
        buildingsSTL = '';
    var origin = new latLon(centerLat, centerLng);
    buildings.forEach(function (building) {
        var coords = [];
        for (var i = 0; i < building.path.length; i++) {
            var point = new latLon(building.path[i].latitude, building.path[i].longitude);
            coords.push(origin.coordinatesTo(point))
        };
        building.coords = coords;
    });
    var fileName = new String;
    buildings.forEach(function (building) {
        var buildingSTL = createSTL(building.coords, building.buildingHeight, building.name, buildingsSTL);
        buildingsSTL += '\n' + buildingSTL;
        fileName += building.name + '_'
    });
    fs.writeFileSync("stlFiles/" + fileName + ".stl", buildingsSTL);
}