[postgis-tickets] [PostGIS] #5089: ST_Reverse does not handle CURVEPOLYGON/COMPOUNDCURVE correctly

[PostGIS]

#5089: ST_Reverse does not handle CURVEPOLYGON/COMPOUNDCURVE correctly
-----------------------+---------------------------
 Reporter:  bhoefling  |      Owner:  strk
     Type:  defect     |     Status:  new
 Priority:  medium     |  Milestone:  PostGIS 3.3.0
Component:  liblwgeom  |    Version:  3.2.x
 Keywords:             |
-----------------------+---------------------------
 ST_Reverse works for CIRCULARSTRING, and for simple  CURVEPOLYGON.

 But if the CURVEPOLYGON contains a COMPOUNDCURVE with more than one
 component, the reverse order is wrong.

 Testcase is from here:

 https://github.com/postgis/postgis/blob/f6def67654c25d812446239036cee44812613748/regress/core/reverse.sql#L47

 Actual Result:

 SELECT 'cplg2', ST_AsText(ST_Reverse('CURVEPOLYGON (COMPOUNDCURVE
 (CIRCULARSTRING (0 0,1 1,1 0),(1 0,0 1),(0 1,0 0)))'::geometry));

  ?column? |                                  st_astext
 ----------+------------------------------------------------------------------------------
  cplg2    | CURVEPOLYGON(COMPOUNDCURVE(CIRCULARSTRING(1 0,1 1,0 0),(0 1,1
 0),(0 0,0 1)))
 (1 row)

 Note that each sub-component is reversed. But it is necessary to
 additionally reverse the order of the components as such. Otherwise, the
 end/start nodes don't match any more.

 EXPECTED:

 CURVEPOLYGON(COMPOUNDCURVE((0 0,0 1), (0 1,1 0), CIRCULARSTRING(1 0,1 1,0
 0)))

 Implementation details:
 lwgeom.c, lwgeom_reverse_in_place(LWGEOM *geom)

 https://github.com/postgis/postgis/blob/2fb15205263248249b1f1dd09abc117e8f67807c/liblwgeom/lwgeom.c#L135

 This CASE needs to be differentiated more.

 Tested on Docker postgis/postgis:13-master

 SELECT postgis_full_version();

 --  POSTGIS="3.3.0dev 3.2.0-398-g4fa57df0b" [EXTENSION] PGSQL="130"
 GEOS="3.11.0dev-CAPI-1.16.0" PROJ="8.2.0" LIBXML="2.9.10" LIBJSON="0.15"
 LIBPROTOBUF="1.3.3" WAGYU="0.5.0 (Internal)" (core procs from "3.1.4
 ded6c34" need upgrade)

 SELECT version();
                                                            version
 -----------------------------------------------------------------------------------------------------------------------------
  PostgreSQL 13.5 (Debian 13.5-1.pgdg110+1) on x86_64-pc-linux-gnu,
 compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit

 Björn

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5089>
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