drain.yaml

# drain map
cameras:
    perspective:
        type: perspective
        vanishing_point: [0, -500]
lights:
    directional1:
        type: directional
        direction: [.1, .5, -1]
        diffuse: .7
        ambient: .5
styles:
    stereo:
        base: polygons
        animated: true
        shaders:
            defines:
                EARTH_RADIUS: 6378137.0 //radius of ellipsoid, WGS84
                PI: 3.14159265358979323846
                HALF_PI: 1.570796327
                QUARTER_PI: .785398163
                deg2rad(d): (d)*PI/180.0
                rad2deg(d): (d)*180.0/PI
            blocks:
                global: |
                    // http://wiki.openstreetmap.org/wiki/Mercator
                    float y2lat_m (float y) { return rad2deg(2.0*atan(exp((y/EARTH_RADIUS)))-HALF_PI); }
                    float x2lon_m (float x) { return rad2deg(x/EARTH_RADIUS); }

                    float lat2y_m (float lat) { return EARTH_RADIUS*log(tan(QUARTER_PI+ deg2rad(lat)/2.0)); }
                    float lon2x_m (float lon) { return deg2rad(lon)*EARTH_RADIUS; }

                    // vec2 stereographic(float lat, float lng, float a, float e, float phi_c, float lambda_0) {
                    vec2 stereographic(float lat, float lng, float phi_c, float lambda_0) {
                        float e=0.08181919; //eccentricity, WGS84
                        // float phi_c=70.; //standard parallel, latitude of true scale
                        // float lambda_0=0.; //meridian along positive Y axis

                        float phi = lat; // this convention varies --
                        float lambda = lng; // sometimes these are switched

                        // convert to radians
                        phi=deg2rad(phi);
                        phi_c=deg2rad(phi_c);
                        lambda=deg2rad(lambda);
                        lambda_0=deg2rad(lambda_0);
                        
                        float pm = 1.;
                        // if the standard parallel is in S.Hemi., switch signs.
                        if (phi_c < 0.) {
                            pm=-1.; //plus or minus, north lat. or south
                            phi=-phi;
                            phi_c=-phi_c;
                            lambda=-lambda;
                            lambda_0=-lambda_0;
                        }
                        
                        float t=tan(PI/4.-phi/2.)/pow(((1.-e*sin(phi))/(1.+e*sin(phi))),(e/2.));
                        float t_c=tan(PI/4. - phi_c/2.)/pow(((1.-e*sin(phi_c))/(1.+e*sin(phi_c))),(e/2.));
                        float m_c=cos(phi_c)/sqrt(pow(1.-pow(e,2.)*(sin(phi_c)),2.));
                        float rho=EARTH_RADIUS*m_c*t/t_c; //true scale at lat phi_c

                        float m=cos(phi)/sqrt(pow(1.-pow(e,2.)*(sin(phi)),2.));
                        float x=pm*rho*sin(lambda-lambda_0);
                        float y=-pm*rho*cos(lambda - lambda_0);
                        float k=rho/(EARTH_RADIUS*m);

                        return vec2(x, y) / 1.;
                    }

                position: |
                    // mercator position of the current vertex, u_map_position = center of screen,
                    // position.xy = vertex screen position in meters from the center of the screen
                    vec2 mercator = u_map_position.xy + position.xy;
                    float lat = y2lat_m(mercator.y);
                    float lon = x2lon_m(mercator.x);

                    // Latitude_Of_Origin
                    // float centerlat = deg2rad(y2lat_m(u_map_position.y));
                    float centerlat = y2lat_m(u_map_position.y);
                    // Central_Meridian
                    // float centerlon = deg2rad(x2lon_m(u_map_position.x));
                    float centerlon = x2lon_m(u_map_position.x);

                    float latwrap = lat % 18910. - 9455.;

                    // position.xy = stereographic(lat, lon);
                    position.xy = stereographic(lat+centerlat, lon, centerlat, centerlon);

    stereolines:
        base: lines
        mix: stereo
sources:
    osm:
        type: TopoJSONTiles
        url:  //vector.mapzen.com/osm/all/{z}/{x}/{y}.topojson?api_key=vector-tiles-_vxMzew
layers:
    boundaries:
        data: { source: osm }
        draw:
            stereolines:
                order: 10
                color: white
                width: 1px
    water:
        data: { source: osm }
        draw:
            stereolines:
                order: 2
                color: [1.000, 1.000, 1.000]
                width: 1px
    # earth:
    #     data: { source: osm }
    #     draw:
    #         stereo:
    #             order: 0
    #             color: '#555'
    # landuse:
    #     data: { source: osm }
    #     draw:
    #         stereo:
    #             order: 1
    #             color: '#666'
    # roads:
    #     data: { source: osm }
    #     draw:
    #         stereolines:
    #             order: 2
    #             color: '#777'
    #             width: 5
    # buildings:
    #     data: { source: osm }
    #     draw:
    #         stereo:
    #             order: 50
    #             color: '#999'
    #             extrude: true