motiejus/wm
1
Fork 0
Code Releases Activity

bend detection

Browse Source
This commit is contained in:
Motiejus Jakštys 2021-05-19 22:57:45 +03:00 committed by Motiejus Jakštys
parent 971e9e5921
commit d6fe1e9979
1 changed files with 19 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
bend.sql
View File

@ -1,3 +1,6 @@
\set ON_ERROR_STOP on
SET plpgsql.extra_errors TO 'all';
create or replace function detect_bends(line geometry) returns table(bend geometry) as $$ create or replace function detect_bends(line geometry) returns table(bend geometry) as $$
/* for each bend, should return: /* for each bend, should return:
- size (area) - size (area)
@ -9,6 +12,8 @@ declare
p1 geometry; p1 geometry;
p2 geometry; p2 geometry;
p3 geometry; p3 geometry;
prev_sign int4;
cur_sign int4;
begin begin
pi = radians(180); pi = radians(180);
@ -16,8 +21,20 @@ begin
p3 = p2; p3 = p2;
p2 = p1; p2 = p1;
p1 = p; p1 = p;
if p3 is null then continue; end if; if p3 is null then
raise notice 'ANGLE %', degrees(pi - st_angle(p1, p2, p2, p3)); continue;
end if;
cur_sign = sign(pi - st_angle(p1, p2, p2, p3));
bend = st_linemerge(st_union(bend, st_makeline(p3, p2)));
if prev_sign + cur_sign = 0 then
if bend is not null then
return next;
end if;
bend = st_makeline(p3, p2);
end if;
prev_sign = cur_sign;
end loop; end loop;
end end
$$ language plpgsql; $$ language plpgsql;