118 lines
3.3 KiB
PL/PgSQL
118 lines
3.3 KiB
PL/PgSQL
\set ON_ERROR_STOP on
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SET plpgsql.extra_errors TO 'all';
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-- wm_bbox clips a geometry by a bounding box around a given object,
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-- matching dimensions of A-class paper (1 by sqrt(2)).
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drop function if exists wm_bbox;
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create function wm_bbox(
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center geometry,
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scaledwidth float
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) returns geometry as $$
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declare
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halfX float;
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halfY float;
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begin
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halfX = scaledwidth / 2;
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halfY = halfX * sqrt(2);
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return st_envelope(
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st_union(
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st_translate(center, halfX, halfY),
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st_translate(center, -halfX, -halfY)
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)
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);
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end $$ language plpgsql;
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-- wm_quadrant divides the given geometry to 4 rectangles
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-- and returns the requested quadrant following cartesian
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-- convention:
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-- +----------+
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-- | II | I |
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--- +----------+
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-- | III | IV |
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-- +-----+----+
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-- matching dimensions of A-class paper (1 by sqrt(2).
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drop function if exists wm_quadrant;
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create function wm_quadrant(
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geom geometry,
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quadrant integer
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) returns geometry as $$
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declare
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xmin float;
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xmax float;
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ymin float;
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ymax float;
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begin
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xmin = st_xmin(geom);
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xmax = st_xmax(geom);
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ymin = st_ymin(geom);
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ymax = st_ymax(geom);
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if quadrant = 1 or quadrant = 2 then
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ymin = (ymin + ymax)/2;
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else
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ymax = (ymin + ymax)/2;
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end if;
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if quadrant = 2 or quadrant = 3 then
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xmax = (xmin + xmax)/2;
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else
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xmin = (xmin + xmax)/2;
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end if;
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return st_intersection(
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geom,
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st_makeenvelope(xmin, ymin, xmax, ymax, st_srid(geom))
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);
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end $$ language plpgsql;
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delete from wm_debug where name like 'salvis%';
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delete from wm_visuals where name like 'salvis%';
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insert into wm_visuals(name, way) values('salvis', (
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with multismall as (
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select st_intersection(
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(select st_union(way) from wm_rivers where name in ('Šalčia', 'Visinčia')),
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wm_bbox(
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st_closestpoint(
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(select way from wm_rivers where name='Šalčia'),
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(select way from wm_rivers where name='Visinčia')
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),
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:scaledwidth
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)
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) ways
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)
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-- protecting against very small bends that were cut
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-- in the corner of the picture
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select st_union(a.geom)
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from st_dump((select ways from multismall)) a
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where st_length(a.geom) >= 100
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));
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do $$
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declare
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i integer;
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geom1 geometry;
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geom2 geometry;
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geom3 geometry;
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begin
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foreach i in array array[16, 64, 256] loop
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geom1 = st_simplify((select way from wm_visuals where name='salvis'), i);
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geom2 = st_simplifyvw((select way from wm_visuals where name='salvis'), i*i);
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insert into wm_visuals(name, way) values
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('salvis-douglas-' || i, geom1),
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('salvis-douglas-' || i || '-chaikin', st_chaikinsmoothing(geom1, 5)),
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('salvis-visvalingam-' || i, geom2),
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('salvis-visvalingam-' || i || '-chaikin', st_chaikinsmoothing(geom2, 5));
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end loop;
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-- 220 doesn't work, because there is an exaggerated bend
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-- near Šalčia-Žeimena crossing, and it "exaggerates" to the
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-- other river.
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-- cross-river crossing detection should be more robust --- and
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-- the current problems are described in the paper.
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foreach i in array array[75, 220] loop
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geom3 = st_simplifywm((select way from wm_visuals where name='salvis'), i, 50, 'salvis-wm-' || i);
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insert into wm_visuals(name, way) values
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('salvis-wm-' || i, geom3);
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end loop;
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end $$ language plpgsql;
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