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split bendattrs to bends and attrs

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this makes code easier to reason about, and some lines shorter (thus
removing splitting requirement).
This commit is contained in:
Motiejus Jakštys 2021-05-11 07:33:41 +03:00
parent 313f95db3a
commit 44ee741e82
1 changed files with 108 additions and 178 deletions
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286
IV/wm.sql
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@ -81,16 +81,14 @@ begin
dbgpolygon = null;
if st_npoints(bends[i]) >= 3 then
dbgpolygon = st_makepolygon(
st_addpoint(bends[i],
st_startpoint(bends[i]))
st_addpoint(bends[i], st_startpoint(bends[i]))
);
end if;
insert into wm_debug(stage, name, gen, nbend, way) values(
'bbends-polygon', dbgname, dbggen, i, dbgpolygon);
end loop;
end if;
end
$$ language plpgsql;
end $$ language plpgsql;
-- wm_fix_gentle_inflections moves bend endpoints following "Gentle Inflection
-- at End of a Bend" section.
@ -141,8 +139,7 @@ begin
'cinflections-polygon', dbgname, dbggen, i, dbgpolygon);
end loop;
end if;
end
$$ language plpgsql;
end $$ language plpgsql;
-- wm_fix_gentle_inflections1 fixes gentle inflections of an array of lines in
-- one direction. An implementation detail of wm_fix_gentle_inflections.
@ -204,8 +201,7 @@ begin
end loop;
end loop;
end
$$ language plpgsql;
end $$ language plpgsql;
-- wm_if_selfcross returns whether baseline of bendi crosses bendj.
-- If it doesn't, returns a null geometry.
@ -235,9 +231,7 @@ begin
end if;
return multi;
end
$$ language plpgsql;
end $$ language plpgsql;
-- wm_self_crossing eliminates self-crossing from the bends, following the
-- article's section "Self-line Crossing When Cutting a Bend".
@ -305,8 +299,7 @@ begin
unnest(bends)
);
end if;
end
$$ language plpgsql;
end $$ language plpgsql;
drop function if exists wm_inflection_angle;
create function wm_inflection_angle (IN bend geometry, OUT angle real) as $$
@ -324,17 +317,13 @@ begin
continue when p3 is null;
angle = angle + abs(pi() - st_angle(p1, p2, p3));
end loop;
end
$$ language plpgsql;
end $$ language plpgsql;
drop function if exists wm_bend_attrs;
drop function if exists wm_isolated_bends;
drop function if exists wm_elimination;
drop function if exists wm_exaggeration;
drop type if exists wm_t_bend_attrs;
create type wm_t_bend_attrs as (
bend geometry,
area real,
drop type if exists wm_t_attrs;
create type wm_t_attrs as (
adjsize real,
baselinelength real,
curvature real,
@ -344,40 +333,66 @@ create function wm_bend_attrs(
bends geometry[],
dbgname text default null,
dbggen integer default null
) returns setof wm_t_bend_attrs as $$
) returns wm_t_attrs[] as $$
declare
cmp float;
i int4;
polygon geometry;
isolation_threshold constant real default 0.5;
attrs wm_t_attrs[];
attr wm_t_attrs;
bend geometry;
res wm_t_bend_attrs;
i int4;
needs_curvature real;
skip_next boolean;
dbglastid integer;
begin
for i in 1..array_length(bends, 1) loop
bend = bends[i];
res = null;
res.bend = bend;
res.adjsize = 0;
res.baselinelength = st_distance(st_startpoint(bend), st_endpoint(bend));
res.curvature = wm_inflection_angle(bend) / st_length(bend);
res.isolated = false;
attr.adjsize = 0;
attr.baselinelength = st_distance(st_startpoint(bend), st_endpoint(bend));
attr.curvature = wm_inflection_angle(bend) / st_length(bend);
attr.isolated = false;
if st_numpoints(bend) >= 3 then
res.adjsize = wm_adjsize(bend);
attr.adjsize = wm_adjsize(bend);
end if;
attrs[i] = attr;
end loop;
for i in 1..array_length(attrs, 1) loop
if dbgname is not null then
insert into wm_debug (stage, name, gen, nbend, way, props) values(
'ebendattrs', dbgname, dbggen, i, bend,
jsonb_build_object(
'adjsize', res.adjsize,
'baselinelength', res.baselinelength,
'curvature', res.curvature
'adjsize', attrs[i].adjsize,
'baselinelength', attrs[i].baselinelength,
'curvature', attrs[i].curvature,
'isolated', false
)
);
) returning id into dbglastid;
end if;
-- first and last bends can never be isolated by definition
if skip_next or i = 1 or i = array_length(attrs, 1) then
skip_next = false;
continue;
end if;
needs_curvature = attrs[i].curvature * isolation_threshold;
if attrs[i-1].curvature < needs_curvature and
attrs[i+1].curvature < needs_curvature then
attr = attrs[i];
attr.isolated = true;
attrs[i] = attr;
skip_next = true;
if dbgname is not null then
update wm_debug
set props=props || jsonb_build_object('isolated', true)
where id=dbglastid;
end if;
end if;
return next res;
end loop;
end;
$$ language plpgsql;
return attrs;
end $$ language plpgsql;
-- sm_st_split a line by a point in a more robust way than st_split.
-- See https://trac.osgeo.org/postgis/ticket/2192
@ -448,8 +463,7 @@ begin
bend = st_setsrid(st_makeline(points), st_srid(bend));
size = wm_adjsize(bend);
end loop;
end
$$ language plpgsql;
end $$ language plpgsql;
-- wm_adjsize calculates adjusted size for a polygon. Can return 0.
drop function if exists wm_adjsize;
@ -474,12 +488,12 @@ begin
if cmp > 0 then
adjsize = (area*(0.75/cmp));
end if;
end
$$ language plpgsql;
end $$ language plpgsql;
-- wm_exaggeration is the Exaggeration Operator described in the WM paper.
create function wm_exaggeration(
INOUT bendattrs wm_t_bend_attrs[],
INOUT bends geometry[],
attrs wm_t_attrs[],
dhalfcircle float,
intersect_patience integer,
dbgname text default null,
@ -488,7 +502,7 @@ create function wm_exaggeration(
) as $$
declare
desired_size constant float default pi()*(dhalfcircle^2)/8;
tmpbendattr wm_t_bend_attrs;
bend geometry;
tmpint geometry;
i integer;
n integer;
@ -496,79 +510,69 @@ declare
begin
mutated = false;
<<bendloop>>
for i in 1..array_length(bendattrs, 1) loop
if bendattrs[i].isolated and bendattrs[i].adjsize < desired_size then
tmpbendattr.bend = wm_exaggerate_bend(
bendattrs[i].bend,
bendattrs[i].adjsize,
desired_size
);
for i in 1..array_length(attrs, 1) loop
if attrs[i].isolated and attrs[i].adjsize < desired_size then
bend = wm_exaggerate_bend(bends[i], attrs[i].adjsize, desired_size);
-- does tmpbendattrs.bend intersect with the previous or next
-- does bend intersect with the previous or next
-- intersect_patience bends? If they do, abort exaggeration for this one.
-- Do close-by bends intersect with this one? Special
-- handling first, because 2 vertices need to be removed before checking.
n = st_npoints(bendattrs[i-1].bend);
n = st_npoints(bends[i-1]);
if n > 3 then
continue when st_intersects(tmpbendattr.bend,
st_removepoint(st_removepoint(bendattrs[i-1].bend, n-1), n-2));
continue when st_intersects(bend,
st_removepoint(st_removepoint(bends[i-1], n-1), n-2));
end if;
n = st_npoints(bendattrs[i+1].bend);
n = st_npoints(bends[i+1]);
if n > 3 then
continue when st_intersects(tmpbendattr.bend,
st_removepoint(st_removepoint(bendattrs[i+1].bend, 0), 0));
continue when st_intersects(bend,
st_removepoint(st_removepoint(bends[i+1], 0), 0));
end if;
for n in -intersect_patience+1..intersect_patience-1 loop
continue when n in (-1, 0, 1);
continue when i+n < 1;
continue when i+n > array_length(bendattrs, 1);
continue when i+n > array_length(attrs, 1);
-- More special handling: if the neigbhoring bend has 3 vertices, the
-- neighbor's neighbor may just touch the tmpbendattr.bend; in this
-- case, the nearest vertex should be removed before comparing.
tmpint = bendattrs[i+n].bend;
tmpint = bends[i+n];
if st_npoints(tmpint) > 2 then
if n = -2 and st_npoints(bendattrs[i+n+1].bend) = 3 then
if n = -2 and st_npoints(bends[i+n+1]) = 3 then
tmpint = st_removepoint(tmpint, st_npoints(tmpint)-1);
elsif n = 2 and st_npoints(bendattrs[i+n-1].bend) = 3 then
elsif n = 2 and st_npoints(bends[i+n-1]) = 3 then
tmpint = st_removepoint(tmpint, 0);
end if;
end if;
continue bendloop when st_intersects(tmpbendattr.bend, tmpint);
continue bendloop when st_intersects(bend, tmpint);
end loop;
-- No intersections within intersect_patience, mutate bend!
mutated = true;
bendattrs[i] = tmpbendattr;
bends[i] = bend;
-- remove last vertex of the previous bend and first vertex of the next
-- bend, because bends always share a line segment together this is
-- duplicated in a few places, because PostGIS does not allow (?)
-- mutating an array when passed to a function.
tmpbendattr.bend = st_removepoint(
bendattrs[i-1].bend,
st_npoints(bendattrs[i-1].bend)-1
);
bendattrs[i-1] = tmpbendattr;
tmpbendattr.bend = st_removepoint(bendattrs[i+1].bend, 0);
bendattrs[i+1] = tmpbendattr;
bends[i-1] = st_removepoint(bends[i-1], st_npoints(bends[i-1])-1);
bends[i+1] = st_removepoint(bends[i+1], 0);
if dbgname is not null then
insert into wm_debug (stage, name, gen, nbend, way) values(
'gexaggeration', dbgname, dbggen, i, bendattrs[i].bend
);
'gexaggeration', dbgname, dbggen, i, bends[i]);
end if;
end if;
end loop;
end $$ language plpgsql;
create function wm_elimination(
INOUT bendattrs wm_t_bend_attrs[],
INOUT bends geometry[],
attrs wm_t_attrs[],
dhalfcircle float,
dbgname text default null,
dbggen integer default null,
@ -579,119 +583,55 @@ declare
leftsize float;
rightsize float;
i int4;
j int4;
tmpbendattr wm_t_bend_attrs;
dbgbends geometry[];
begin
mutated = false;
i = 1;
while i < array_length(bendattrs, 1)-1 loop
while i < array_length(attrs, 1)-1 loop
i = i + 1;
continue when bendattrs[i].adjsize = 0;
continue when bendattrs[i].adjsize > desired_size;
continue when attrs[i].adjsize = 0;
continue when attrs[i].adjsize > desired_size;
if i = 2 then
leftsize = bendattrs[i].adjsize + 1;
leftsize = attrs[i].adjsize + 1;
else
leftsize = bendattrs[i-1].adjsize;
leftsize = attrs[i-1].adjsize;
end if;
if i = array_length(bendattrs, 1)-1 then
rightsize = bendattrs[i].adjsize + 1;
if i = array_length(attrs, 1)-1 then
rightsize = attrs[i].adjsize + 1;
else
rightsize = bendattrs[i+1].adjsize;
rightsize = attrs[i+1].adjsize;
end if;
continue when bendattrs[i].adjsize >= leftsize;
continue when bendattrs[i].adjsize >= rightsize;
continue when attrs[i].adjsize >= leftsize;
continue when attrs[i].adjsize >= rightsize;
-- Local minimum. Elminate bend!
mutated = true;
tmpbendattr.bend = st_makeline(
st_pointn(bendattrs[i].bend, 1),
st_pointn(bendattrs[i].bend, -1)
);
bendattrs[i] = tmpbendattr;
bends[i] = st_makeline(st_pointn(bends[i], 1), st_pointn(bends[i], -1));
-- remove last vertex of the previous bend and
-- first vertex of the next bend, because bends always
-- share a line segment together
tmpbendattr.bend = st_removepoint(
bendattrs[i-1].bend,
st_npoints(bendattrs[i-1].bend)-1
);
bendattrs[i-1] = tmpbendattr;
tmpbendattr.bend = st_removepoint(bendattrs[i+1].bend, 0);
bendattrs[i+1] = tmpbendattr;
bends[i-1] = st_removepoint(bends[i-1], st_npoints(bends[i-1])-1);
bends[i+1] = st_removepoint(bends[i+1], 0);
-- the next bend's adjsize is now messed up; it should not be taken
-- into consideration for other local minimas. Skip over 2.
i = i + 2;
end loop;
if dbgname is not null then
for j in 1..array_length(bendattrs, 1) loop
dbgbends[j] = bendattrs[j].bend;
end loop;
insert into wm_debug(stage, name, gen, nbend, way) values(
'helimination',
dbgname,
dbggen,
generate_subscripts(dbgbends, 1),
unnest(dbgbends)
generate_subscripts(bends, 1),
unnest(bends)
);
end if;
end
$$ language plpgsql;
end $$ language plpgsql;
create function wm_isolated_bends(
INOUT bendattrs wm_t_bend_attrs[],
dbgname text default null,
dbggen integer default null
) as $$
declare
-- if neighbor's curvatures are within this fraction of the current bend
isolation_threshold constant real default 0.5;
this real;
skip_next bool;
res wm_t_bend_attrs;
i int4;
last_id integer;
begin
for i in 1..array_length(bendattrs, 1) loop
if dbgname is not null then
insert into wm_debug (stage, name, gen, nbend, way, props) values(
'fisolated_bends', dbgname, dbggen, i, bendattrs[i].bend,
jsonb_build_object('isolated', false)
) returning id into last_id;
end if;
-- first and last bends cannot be isolated
if i = 1 or i = array_length(bendattrs, 1) then
continue;
end if;
res = bendattrs[i];
if skip_next then
skip_next = false;
else
this = bendattrs[i].curvature * isolation_threshold;
if bendattrs[i-1].curvature < this and
bendattrs[i+1].curvature < this then
res.isolated = true;
bendattrs[i] = res;
skip_next = true;
if dbgname is not null then
update wm_debug
set props=props || jsonb_build_object('isolated', true)
where id=last_id;
end if;
end if;
end if;
end loop;
end
$$ language plpgsql;
drop function if exists ST_SimplifyWM_Estimate;
create function ST_SimplifyWM_Estimate(
@ -717,8 +657,7 @@ begin
npoints = npoints + st_numpoints(lines[i]);
end loop;
secs = npoints / 33;
end
$$ language plpgsql;
end $$ language plpgsql;
-- ST_SimplifyWM simplifies a given geometry using Wang & Müller's
-- "Line Generalization Based on Analysis of Shape Characteristics" algorithm,
@ -742,7 +681,7 @@ declare
line geometry;
lines geometry[];
bends geometry[];
bendattrs wm_t_bend_attrs[];
attrs wm_t_attrs[];
mutated boolean;
l_type text;
begin
@ -773,31 +712,23 @@ begin
select * from wm_self_crossing(bends, dbgname, gen) into bends, mutated;
if mutated then
lines[i] = st_linemerge(st_union(bends));
gen = gen + 1;
continue;
if not mutated then
attrs = wm_bend_attrs(bends, dbgname, gen);
select * from wm_exaggeration(bends, attrs,
dhalfcircle, intersect_patience, dbgname, gen) into bends, mutated;
end if;
bendattrs = array((select wm_bend_attrs(bends, dbgname, gen)));
bendattrs = wm_isolated_bends(bendattrs, dbgname, gen);
select * from wm_exaggeration(
bendattrs, dhalfcircle, intersect_patience, dbgname, gen
) into bendattrs, mutated;
-- TODO: wm_combination
if not mutated then
select * from wm_elimination(
bendattrs, dhalfcircle, dbgname, gen) into bendattrs, mutated;
select * from wm_elimination(bends, attrs,
dhalfcircle, dbgname, gen) into bends, mutated;
end if;
if mutated then
for j in 1..array_length(bendattrs, 1) loop
bends[j] = bendattrs[j].bend;
end loop;
lines[i] = st_linemerge(st_union(bends));
if st_geometrytype(lines[i]) != 'ST_LineString' then
-- For manual debugging:
--insert into wm_manual(name, way)
@ -821,5 +752,4 @@ begin
elseif l_type = 'ST_MultiLineString' then
return st_union(lines);
end if;
end
$$ language plpgsql;
end $$ language plpgsql;