From 9a9689da023062c912a3410fcc644e3e187a37d0 Mon Sep 17 00:00:00 2001 From: Sandro Santilli Date: Wed, 18 May 2011 07:23:06 +0000 Subject: [PATCH] Add a short paragraph about the semantic of edge's next_left_edge and next_right_edge fields. git-svn-id: http://svn.osgeo.org/postgis/trunk@7184 b70326c6-7e19-0410-871a-916f4a2858ee --- topology/README | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/topology/README b/topology/README index b89b1b943..4b8c0076b 100644 --- a/topology/README +++ b/topology/README @@ -96,7 +96,14 @@ under you topology schema: * face_id integer PRIMARY KEY * mbr box2d ( can be NULL ) -Details on semantic are contained in the SQL/MM specification, which +The next_*_edge of an edge is the edge you encounter next while going +around the specified face (right or left) in counterclockwise order +(so that the face is on your left). Note that due to this definition +the edge being considered is traversed in reverse order when traversing +its "right" face. The values are signed to indicate wheter the next edge +will be traversed in its original or reversed orientation. + +More details on semantic are contained in the SQL/MM specification, which this implementation follows as for these views structure. ==Validating topology data -- 2.50.1