Support motorway highway labels for lower zooms

layers/highway_name/highway_name.yaml

@@ -10,7 +10,7 @@ layer:
   datasource:
     geometry_field: geometry
     srid: 900913
-    query: (SELECT osm_id, geometry, name, class::text, subclass FROM layer_highway_name(!bbox!, z(!scale_denominator!))) AS t
+    query: (SELECT osm_id, geometry, name, ref, class::text, subclass FROM layer_highway_name(!bbox!, z(!scale_denominator!))) AS t
 schema:
   - ./merge_highways.sql
   - ./layer.sql

layers/highway_name/layer.sql

@@ -1,15 +1,27 @@
 CREATE OR REPLACE FUNCTION layer_highway_name(bbox geometry, zoom_level integer)
-RETURNS TABLE(osm_id bigint, geometry geometry, name text, class highway_class, subclass text) AS $$
-    SELECT osm_id, geometry, name, to_highway_class(highway) AS class, highway AS subclass FROM (
-        SELECT * FROM osm_highway_name_linestring
-        WHERE zoom_level = 12 AND to_highway_class(highway) < 'minor_road'::highway_class AND NOT highway_is_link(highway)
+RETURNS TABLE(osm_id bigint, geometry geometry, name text, ref text, class highway_class, subclass text) AS $$
+    SELECT osm_id, geometry, name, ref, to_highway_class(highway) AS class, highway AS subclass FROM (
+        SELECT * FROM osm_highway_name_linestring_gen3
+        WHERE zoom_level = 8
+        UNION ALL
+        SELECT * FROM osm_highway_name_linestring_gen2
+        WHERE zoom_level = 9
+        UNION ALL
+        SELECT * FROM osm_highway_name_linestring_gen1
+        WHERE zoom_level BETWEEN 10 AND 11
         UNION ALL
         SELECT * FROM osm_highway_name_linestring
-        WHERE zoom_level = 13 AND to_highway_class(highway) < 'path'::highway_class
+        WHERE zoom_level = 12
+            AND to_highway_class(highway) < 'minor_road'::highway_class
+            AND NOT highway_is_link(highway)
+        UNION ALL
+        SELECT * FROM osm_highway_name_linestring
+        WHERE zoom_level = 13
+            AND to_highway_class(highway) < 'path'::highway_class
         UNION ALL
         SELECT * FROM osm_highway_name_linestring
         WHERE zoom_level >= 14
     ) AS zoom_levels
-    WHERE geometry && bbox
+    WHERE geometry && bbox AND LineLabel(zoom_level, COALESCE(NULLIF(name, ''), ref), geometry)
     ORDER BY z_order ASC;
 $$ LANGUAGE SQL IMMUTABLE;

layers/highway_name/merge_highways.sql

@@ -10,20 +10,43 @@ CREATE TABLE IF NOT EXISTS osm_highway_name_linestring AS (
 		member_osm_ids[0] AS osm_id,
 		member_osm_ids,
 		name,
+        ref,
 		highway,
 		z_order
 	FROM (
 		SELECT
 			ST_LineMerge(ST_Union(geometry)) AS geometry,
 			name,
+            ref,
 			highway,
 			min(z_order) AS z_order,
 			array_agg(DISTINCT osm_id) AS member_osm_ids
 	    FROM osm_highway_linestring
         -- We only care about roads for labelling
-	    WHERE name <> ''
-	    GROUP BY name, highway
+	    WHERE name <> '' OR ref <> ''
+	    GROUP BY name, highway, ref
 	) AS highway_union
 );
 
-CREATE INDEX IF NOT EXISTS osm_highway_name_linestring_geometry_idx ON osm_important_place_point USING gist(geometry);
+CREATE INDEX IF NOT EXISTS osm_highway_name_linestring_geometry_idx ON osm_highway_name_linestring USING gist(geometry);
+
+CREATE TABLE IF NOT EXISTS osm_highway_name_linestring_gen1 AS (
+    SELECT ST_Simplify(geometry, 50) AS geometry, osm_id, member_osm_ids, name, ref, highway, z_order
+    FROM osm_highway_name_linestring
+    WHERE highway IN ('motorway','trunk')  AND ST_Length(geometry) > 8000
+);
+CREATE INDEX IF NOT EXISTS osm_highway_name_linestring_gen1_geometry_idx ON osm_highway_name_linestring_gen1 USING gist(geometry);
+
+CREATE TABLE IF NOT EXISTS osm_highway_name_linestring_gen2 AS (
+    SELECT ST_Simplify(geometry, 120) AS geometry, osm_id, member_osm_ids, name, ref, highway, z_order
+    FROM osm_highway_name_linestring_gen1
+    WHERE highway IN ('motorway','trunk')  AND ST_Length(geometry) > 14000
+);
+CREATE INDEX IF NOT EXISTS osm_highway_name_linestring_gen2_geometry_idx ON osm_highway_name_linestring_gen2 USING gist(geometry);
+
+CREATE TABLE IF NOT EXISTS osm_highway_name_linestring_gen3 AS (
+    SELECT ST_Simplify(geometry, 120) AS geometry, osm_id, member_osm_ids, name, ref, highway, z_order
+    FROM osm_highway_name_linestring_gen2
+    WHERE highway = 'motorway' AND ST_Length(geometry) > 20000
+);
+CREATE INDEX IF NOT EXISTS osm_highway_name_linestring_gen3_geometry_idx ON osm_highway_name_linestring_gen3 USING gist(geometry);