[postgis-tickets] [PostGIS] #2228: topology.AsTopoJSON(TopoGeometry)

[PostGIS]

#2228: topology.AsTopoJSON(TopoGeometry)
--------------------------+-------------------------------------------------
  Reporter:  strk         |       Owner:  strk         
      Type:  enhancement  |      Status:  reopened     
  Priority:  medium       |   Milestone:  PostGIS 2.1.0
 Component:  topology     |     Version:  trunk        
Resolution:               |    Keywords:  history 2.1.0
--------------------------+-------------------------------------------------
Changes (by strk):

  * status:  closed => reopened
  * resolution:  fixed =>


Comment:

 Reopening because according to the specs a MultiPolygon must be
 represented as an array of Polygons. The current code is instead using a
 single array of _rings_ whereas ring orientation tells if a ring is an
 hole or a shell but nothing tells which hole belongs to which shell.

 I've been thinking a way to figure out what's an hole and what's a shell:
 while walking a ring, the code can keep track of which faces are being
 bound;
 at the end of ring any still-not-visited edge having one of the visited
 faces on any side will surely be an hole belonging to the previous shell.

 Holes within an embedded face will need to be tested,
 like this:

 {{{
  TopoGeometry formed by (F1,F2)
  +----------+
  |    F1    |
  | +------+ |
  | |  F2  | |
  | | +--+ | |
  | | |F3| | |
  | | +--+ | |
  | +------+ |
  +----------+
 }}}

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2228#comment:5>
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