/**
 * Converts spherical web mercator to tile pixel X/Y at zoom level 0
 * for 256x256 tile size and inverts y coordinates. (EPSG: 3857)
 *
 * @param {L.point} p Leaflet point with web mercator coordinates
 * @return {L.point} Leaflet point with tile pixel x and y corrdinates
 */
function mercatorToPixels(p)  {
  var pixelX = (p.x + (EARTH_EQUATOR / 2.0)) / (EARTH_EQUATOR / TILE_SIZE);
  var pixelY = ((p.y - (EARTH_EQUATOR / 2.0)) / (EARTH_EQUATOR / -TILE_SIZE));
  return L.point(pixelX, pixelY);
}

/**
 * Converts latitude/longitude to tile pixel X/Y at zoom level 0
 * for 256x256 tile size and inverts y coordinates. (EPSG: 4326)
 *
 * @param {L.point} p Leaflet point in EPSG:3857
 * @return {L.point} Leaflet point with tile pixel x and y corrdinates
 */
function latLonToPixels(lat, lon) {
  var sinLat = Math.sin(lat * Math.PI / 180.0);
  var pixelX = ((lon + 180) / 360) * TILE_SIZE;
  var pixelY = (0.5 - Math.log((1 + sinLat) / (1 - sinLat)) / (Math.PI * 4)) * TILE_SIZE;
  return L.point(pixelX, pixelY);
}