obs-portal/tile-generator/layers/obs_events/layer.sql

CREATE OR REPLACE FUNCTION layer_obs_events(bbox geometry, zoom_level int)
RETURNS TABLE(event_id bigint, geometry geometry, distance_overtaker float, distance_stationary float, direction int, course float, speed float, way_id bigint) AS $$

    SELECT
      id::bigint as event_id,
      ST_Transform(overtaking_event.geometry, 3857) as geometry,
      distance_overtaker,
      distance_stationary,
      (case when direction_reversed then -1 else 1 end)::int as direction,
      course,
      speed,
      way_id::bigint as way_id
    FROM overtaking_event
    WHERE
      zoom_level >= 10 AND
      ST_Transform(overtaking_event.geometry, 3857) && bbox;

$$ LANGUAGE SQL IMMUTABLE;