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wip wm_exaggerate

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Motiejus Jakštys 2021-05-19 22:57:49 +03:00 committed by Motiejus Jakštys
parent 69f0878bb6
commit 95e515b5cc
2 changed files with 42 additions and 12 deletions
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13
test.sql
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@ -188,3 +188,16 @@ begin
perform assert_equals(fig8gen2, st_astext(eliminations[2])); perform assert_equals(fig8gen2, st_astext(eliminations[2]));
perform assert_equals(fig8gen3, st_astext(eliminations[3])); perform assert_equals(fig8gen3, st_astext(eliminations[3]));
end $$ language plpgsql; end $$ language plpgsql;
-- testing wm_exaggerate in isolation
do $$
declare
fig3b2 geometry;
bend geometry;
size float;
begin
select way from wm_debug where name='fig3' and stage='bbends' and gen=1 and nbend=2 into fig3b2;
size = wm_adjsize(fig3b2);
--bend = wm_exaggerate(fig3b2, size, 50.);
--insert into wm_debug(stage, name, gen, nbend, way) values('manual', 'fig3', 1, 1, bend);
end $$ language plpgsql;

41
wm.sql
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@ -409,16 +409,20 @@ $$ language plpgsql;
-- wm_exaggerate exaggerates a given bend. Must be a simple linestring. -- wm_exaggerate exaggerates a given bend. Must be a simple linestring.
drop function if exists wm_exaggerate; drop function if exists wm_exaggerate;
create function wm_exaggerate( create function wm_exaggerate(
bend geometry, INOUT bend geometry,
size real, size float,
desired_size real desired_size float
) returns geometry as $$ ) as $$
declare declare
step constant float default 1.5; -- line length multiplier per step scale constant float default 2; -- per-step scaling factor
midpoint geometry; -- midpoint of the baseline midpoint geometry; -- midpoint of the baseline
splitbend geometry; -- bend split across farthest point splitbend geometry; -- bend split across farthest point
bendm geometry; -- bend with coefficients to prolong the lines bendm geometry; -- bend with coefficients to prolong the lines
points geometry[];
begin begin
if size = 0 then
raise 'unable to exaggerate a zero-area bend';
end if;
midpoint = st_lineinterpolatepoint(st_makeline( midpoint = st_lineinterpolatepoint(st_makeline(
st_pointn(bend, 1), st_pointn(bend, 1),
st_pointn(bend, -1) st_pointn(bend, -1)
@ -431,15 +435,28 @@ begin
); );
-- Convert bend to LINESTRINGM, where M is the fraction by how -- Convert bend to LINESTRINGM, where M is the fraction by how
-- much the point will be prolonged. -- much the point will be prolonged:
-- Currently using linear interpolation; can be updated to gaussian -- 1. draw a line between midpoint and the point on the bend.
-- or so (then interpolate manually instead of relying on st_addmeasure) -- 2. multiply the line length by M. Midpoint stays intact.
bendm = st_linemerge(st_union( -- 3. the new set of lines form a new bend.
st_addmeasure(st_geometryn(splitbend, 1), 0, frac),
st_addmeasure(st_geometryn(splitbend, 2), frac, 0)
));
-- Uses linear interpolation; can be updated to gaussian or similar;
-- then interpolate manually instead of relying on st_addmeasure.
bendm = st_union(
st_addmeasure(st_geometryn(splitbend, 1), 1, scale),
st_addmeasure(st_geometryn(splitbend, 2), scale, 1)
);
points = array((
select st_scale(
st_makepoint(st_x(geom), st_y(geom)),
st_makepoint(st_m(geom), st_m(geom)),
midpoint
)
from st_dumppoints(bendm)
order by path[1], path[2]
));
bend = st_makeline(points);
size = wm_adjsize(bend); size = wm_adjsize(bend);
end loop; end loop;