27 lines
661 B
PL/PgSQL
27 lines
661 B
PL/PgSQL
create or replace function detect_bends(line geometry) returns table(bend geometry) as $$
|
|
/* for each bend, should return:
|
|
- size (area)
|
|
- shape (cmp, compactness index)
|
|
*/
|
|
declare
|
|
pi real;
|
|
p geometry;
|
|
p1 geometry;
|
|
p2 geometry;
|
|
p3 geometry;
|
|
begin
|
|
pi = radians(180);
|
|
|
|
for p in (select (dp).geom from st_dumppoints(line) as dp) loop
|
|
p3 = p2;
|
|
p2 = p1;
|
|
p1 = p;
|
|
if p3 is null then continue; end if;
|
|
raise notice 'ANGLE %', degrees(pi - st_angle(p1, p2, p2, p3));
|
|
end loop;
|
|
end
|
|
$$ language plpgsql;
|
|
|
|
drop table if exists bends;
|
|
create table bends as (select * from detect_bends((select way from figures where name='fig3')));
|