Mapbox-gl-js: Dashed line dashes are clipped & offset at tile boundaries

[ezheidtmann]

mapbox-gl-js version: 0.40.1

Steps to Trigger Behavior

1. Draw line with line-dasharray: [0.1, 1.8] and line-cap: round that crosses tile boundary

mapboxgl.accessToken = 'pk.eyJ1IjoicXVpY2tseXdpbGxpYW0iLCJhIjoibmZ3UkZpayJ9.8gNggPy6H5dpzf4Sph4-sA';
var map = new mapboxgl.Map({
    container: 'map',
    style: 'mapbox://styles/mapbox/streets-v9',
    center: [ -122.63480377210192, 45.49858719777322],       
    zoom: 20.505
});

map.showTileBoundaries = true;

map.on('load', function () {

    map.addLayer({
        "id": "route",
        "type": "line",
        "source": {
            "type": "geojson",
            "data": {
                "type": "Feature",
                "properties": {},
                "geometry": {
                    "type": "LineString",
                    "coordinates": [[-122.63332018999998, 45.49907065], [-122.63635848, 45.498128739999984]]
                }
            }
        },
        "layout": {
            "line-join": "round",
            "line-cap": "round"
        },
        "paint": {
            "line-color": "#191",
            "line-width": {
            'base': 1.5,
            'stops': [
                [14, 5],
                [18, 20],
            ],
        },
            "line-dasharray": [0.1, 1.8]
        }
    });
});

jsbin: http://jsbin.com/kiqinefopa/edit?html,output

Expected Behavior

Dashes are shown at regular spacing regardless of tile boundary locations; no artifacts are visible at tile boundaries

Actual Behavior

Dash positions appear shift between tiles and are clipped at tile boundaries. The effect varies with zoom level.

[jingsam]

This issue will not be fixed in the near future. As dash lines of each tile are rendered independently, shifted dash in the boundaries is unavoidable.

[mzdraper]

Noticed this on lines too.