Tangram scene for the Morgantown PRT

prt.yaml

import: https://mapzen.com/carto/zinc-style/zinc-style.yaml
    
sources:
    mapzen:
        type: TopoJSON
        url: https://vector.mapzen.com/osm/all/{z}/{x}/{y}.topojson
    stops:
        type: GeoJSON
        url: https://transit.land/api/v1/stops.geojson?served_by=o-dpp1s-wvuprt

styles:
    ants:
        base: lines
        blend: overlay
        texcoords: true
        animated: true
        shaders:
            blocks:
                color: |
                    color.a = step(.95,fract((u_time/10.50)-v_texcoord.y*.05));
layers:
    PRT:
        data:
            source: mapzen
            layer: roads 
        filter: { name: PRT }
        draw:
            lines:
                order: 499
                width: 2px
                color: [0.290, 0.290, 0.835, 1.00]
            outlines:
                style: lines
                order: 4
                color: cyan
                width: 3px
                order: 498
    stops:
        data:
            source: stops
        draw:
            points1:
                style: points
                collide: false
                color: [0.812, 0.651, 0.129, 0.80]
                size: 30px
            points2:
                style: points
                collide: false
                color: [1.000, 1.000, 1.000, 1.00]
                size: 20px
            text:
                font:
                    family: Helvetica
                    size: 50px
                    fill: red
                order: global.order-top