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wip detecting crossings

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Motiejus Jakštys 2021-05-19 22:57:45 +03:00 committed by Motiejus Jakštys
parent d5eb0d7440
commit 3afa2169c3
1 changed files with 16 additions and 5 deletions
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wm.sql
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@ -165,6 +165,8 @@ $$ language plpgsql;
-- article's section "Self-line Crossing When Cutting a Bend".
create or replace function self_crossing(INOUT bends geometry[]) as $$
declare
i int4;
j int4;
pi real;
angle real;
p geometry;
@ -176,12 +178,12 @@ begin
pi = radians(180);
-- go through the bends and find one where sum of inflection angle is >180
foreach bend in array bends loop
for i in 1..array_length(bends, 1) loop
angle = 0;
p3 = null;
p2 = null;
p1 = null;
for p in (select geom from st_dumppoints(bend) order by path[1] asc) loop
p2 = null;
p3 = null;
for p in (select geom from st_dumppoints(bends[i]) order by path[1] asc) loop
p3 = p2;
p2 = p1;
p1 = p;
@ -192,7 +194,16 @@ begin
end loop;
if abs(angle) > pi then
raise notice 'maybe self-crossing bend %: %', st_astext(bend), round(degrees(abs(angle)));
raise notice 'maybe self-crossing bend %: %', st_astext(bends[i]), round(degrees(abs(angle)));
-- sum of inflection angles for this bend is >180, so it may be self-crossing.
-- now try to find another bend in this line that crosses this one.
for j in 1..array_length(bends, 1) loop
continue when i = j;
end loop;
end if;
end loop;