diff --git a/notes.txt b/notes.txt index 761e3d8..f2f1ffd 100644 --- a/notes.txt +++ b/notes.txt @@ -40,11 +40,6 @@ inflection angles (AB in our examples) must be crossed with all the other bends to detect a possible line-crossing. This is O(N*M), where N is the total number of line segments, and M is the number of qualifying bends. It is expensive. -This may be simplified: if other bend's endpoints (A' and B') are in the same -sub-plane as divided by AB, then the bend can be skipped from checking if it -intersects with AB. Some intersections may be missed (see the last example), -but they will be eliminated by joining A and B anyway. - Also, there is another way to remove self-crossing, without removing most of the bend. E.g. from: @@ -69,4 +64,4 @@ To: \__________| But perhaps it doesn't look quite as natural. I will trust the original -article to do the right thing here. +article to do the right thing here and remove the bend altogether. diff --git a/tests.sql b/tests.sql index 26cd318..586dcf8 100644 --- a/tests.sql +++ b/tests.sql @@ -18,7 +18,7 @@ create table figures (name text, way geometry); --insert into figures (name, way) values ('fig3-1',ST_GeomFromText('LINESTRING(0 0,12 0,13 4,20 2,20 0,32 0,33 10,38 16,43 15,44 10,44 0)')); --insert into figures (name, way) values ('fig5',ST_GeomFromText('LINESTRING(0 39,19 52,27 77,26 104,41 115,49 115,65 103,65 75,53 45,63 15,91 0)')); insert into figures (name, way) values ('fig6',ST_GeomFromText('LINESTRING(84 47,91 59,114 64,122 80,116 92,110 93,106 106,117 118,136 107,135 76,120 45,125 39,141 39,147 32)')); ---insert into figures (name, way) values ('fig6-rev',ST_Reverse(ST_Translate((select way from figures where name='fig6'), 80, 0))); +insert into figures (name, way) values ('fig6-rev',ST_Reverse(ST_Translate((select way from figures where name='fig6'), 80, 0))); --insert into figures (name, way) values ('inflection-1',ST_GeomFromText('LINESTRING(110 24,114 20,133 20,145 15,145 0,136 5,123 7,114 7,111 2)')); drop table if exists debug; diff --git a/wm.sql b/wm.sql index b2a9b6f..34e364f 100644 --- a/wm.sql +++ b/wm.sql @@ -178,8 +178,6 @@ declare p3 geometry; a geometry; b geometry; - s2 real; - s3 real; bend geometry; this geometry; multi geometry; @@ -224,20 +222,10 @@ begin raise notice 'j: %, i: %', j, i; - -- are p2 and p3 on the different sides of line(p0,p1)? vector - -- multiplication; https://stackoverflow.com/questions/1560492/ - s2 = (st_x(p0)-st_x(p1)*(st_y(p2)-st_y(p1))- - (st_y(p0)-st_y(p1))*(st_x(p2)-st_x(p1))); - s3 = (st_x(p0)-st_x(p1)*(st_y(p3)-st_y(p1))- - (st_y(p0)-st_y(p1))*(st_x(p3)-st_x(p1))); - raise notice 'sign(s2): %, sign(s3): %', sign(s2), sign(s3); - continue when sign(s2) = sign(s3); - -- do end vertices of bend[i] cross bend[j]? a = st_pointn(bends[i], 1); b = st_pointn(bends[i], -1); multi = st_split(bends[j], st_makeline(a, b)); - insert into debug (i, way) values (0, st_geometryn(multi, 1)); raise notice 'bends[i]: %', st_astext(bends[i]); raise notice 'bends[j]: %', st_astext(bends[j]); raise notice 'a: %, b: %', st_astext(a), st_astext(b);