wm/visuals.sql

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