commit a4e42296272a240ae61186ad6ae6bbce5bb9a9ea (tree)
parent 534a9b98141b191016bc2939f0f5c51b69c4f767
Author: Motiejus Jakštys <motiejus@uber.com>
Date: Tue, 4 May 2021 21:54:46 +0300
move size calculation to its own function
Diffstat:
| M | IV/wm.sql | | | 90 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------- |
1 file changed, 68 insertions(+), 22 deletions(-)
diff --git a/IV/wm.sql b/IV/wm.sql
@@ -358,7 +358,6 @@ drop type if exists wm_t_bend_attrs;
create type wm_t_bend_attrs as (
bend geometry,
area real,
- cmp real,
adjsize real,
baselinelength real,
curvature real,
@@ -370,7 +369,7 @@ create function wm_bend_attrs(
dbggen integer default null
) returns setof wm_t_bend_attrs as $$
declare
- fourpi constant real default 4*radians(180);
+ cmp float;
i int4;
polygon geometry;
bend geometry;
@@ -380,27 +379,12 @@ begin
bend = bends[i];
res = null;
res.bend = bend;
- res.area = 0;
- res.cmp = 0;
res.adjsize = 0;
res.baselinelength = st_distance(st_startpoint(bend), st_endpoint(bend));
res.curvature = wm_inflection_angle(bend) / st_length(bend);
res.isolated = false;
if st_numpoints(bend) >= 3 then
- polygon = st_makepolygon(st_addpoint(bend, st_startpoint(bend)));
- -- Compactness Index (cmp) is defined as "the ratio of the area of the
- -- polygon over the circle whose circumference length is the same as the
- -- length of the circumference of the polygon". I assume they meant the
- -- area of the circle. So here goes:
- -- 1. get polygon area P.
- -- 2. get polygon perimeter = u. Pretend it's our circle's circumference.
- -- 3. get A (area) of the circle from u: A = u^2/(4pi)
- -- 4. divide P by A: cmp = P/A = P/(u^2/(4pi)) = 4pi*P/u^2
- res.area = st_area(polygon);
- res.cmp = fourpi*res.area/(st_perimeter(polygon)^2);
- if res.cmp > 0 then
- res.adjsize = (res.area*(0.75/res.cmp));
- end if;
+ res.adjsize = wm_adjsize(bend);
end if;
if dbgname is not null then
@@ -411,8 +395,6 @@ begin
i,
bend,
jsonb_build_object(
- 'area', res.area,
- 'cmp', res.cmp,
'adjsize', res.adjsize,
'baselinelength', res.baselinelength,
'curvature', res.curvature
@@ -424,6 +406,72 @@ begin
end;
$$ language plpgsql;
+-- wm_exaggerate exaggerates a given bend. Must be a simple linestring.
+drop function if exists wm_exaggerate;
+create function wm_exaggerate(
+ bend geometry,
+ size real,
+ desired_size real
+) returns geometry as $$
+declare
+ step constant float default 1.5; -- line length multiplier per step
+ midpoint geometry; -- midpoint of the baseline
+ splitbend geometry; -- bend split across farthest point
+ bendm geometry; -- bend with coefficients to prolong the lines
+begin
+ midpoint = st_lineinterpolatepoint(st_makeline(
+ st_pointn(bend, 1),
+ st_pointn(bend, -1)
+ ), .5);
+
+ while size < desired_size loop
+ splitbend = st_split(
+ bend,
+ st_pointn(st_longestline(midpoint, bend), -1)
+ );
+
+ -- Convert bend to LINESTRINGM, where M is the fraction by how
+ -- much the point will be prolonged.
+ -- Currently using linear interpolation; can be updated to gaussian
+ -- or so (then interpolate manually instead of relying on st_addmeasure)
+ bendm = st_linemerge(st_union(
+ st_addmeasure(st_geometryn(splitbend, 1), 0, frac),
+ st_addmeasure(st_geometryn(splitbend, 2), frac, 0)
+ ));
+
+
+
+ size = wm_adjsize(bend);
+ end loop;
+end
+$$ language plpgsql;
+
+-- wm_adjsize calculates adjusted size for a polygon. Can return 0.
+drop function if exists wm_adjsize;
+create function wm_adjsize(bend geometry, OUT adjsize float) as $$
+declare
+ polygon geometry;
+ area float;
+ cmp float;
+begin
+ adjsize = 0;
+ polygon = st_makepolygon(st_addpoint(bend, st_startpoint(bend)));
+ -- Compactness Index (cmp) is defined as "the ratio of the area of the
+ -- polygon over the circle whose circumference length is the same as the
+ -- length of the circumference of the polygon". I assume they meant the
+ -- area of the circle. So here goes:
+ -- 1. get polygon area P.
+ -- 2. get polygon perimeter = u. Pretend it's our circle's circumference.
+ -- 3. get A (area) of the circle from u: A = u^2/(4pi)
+ -- 4. divide P by A: cmp = P/A = P/(u^2/(4pi)) = 4pi*P/u^2
+ area = st_area(polygon);
+ cmp = 4*pi()*area/(st_perimeter(polygon)^2);
+ if cmp > 0 then
+ adjsize = (area*(0.75/cmp));
+ end if;
+end
+$$ language plpgsql;
+
create function wm_exaggeration(
INOUT bendattrs wm_t_bend_attrs[],
dhalfcircle float,
@@ -432,7 +480,6 @@ create function wm_exaggeration(
OUT mutated boolean
) as $$
declare
- area_threshold float;
begin
end
@@ -552,7 +599,6 @@ begin
res.bend,
jsonb_build_object(
'area', res.area,
- 'cmp', res.cmp,
'adjsize', res.adjsize,
'baselinelength', res.baselinelength,
'curvature', res.curvature,
