From: Sandro Santilli Date: Wed, 8 Dec 2004 14:46:48 +0000 (+0000) Subject: updated X-Git-Tag: pgis_1_0_0RC1~170 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=11918a9e0cb8f1df777cec8f8e8488e465961253;p=postgis updated git-svn-id: http://svn.osgeo.org/postgis/trunk@1127 b70326c6-7e19-0410-871a-916f4a2858ee --- diff --git a/examples/wkb_reader/README b/examples/wkb_reader/README index 9bae95b47..757d3df86 100644 --- a/examples/wkb_reader/README +++ b/examples/wkb_reader/README @@ -11,15 +11,16 @@ used for transfer between servers and clients that are not the same endian See http://www.opengis.org/techno/specs/99-049.rtf page 3-24 for the WKB specification. -3d geometries are encoded as in OGR by adding 32768 to the type. Points are -then 24 bytes (X,Y,Z) instead of 16 bytes (X,Y). +Z and M coordinates presence is encoded by or'ing WKBZOFFSET (0x80000000) +and WKBMOFFSET (0x40000000) to the type. +Points can then be 24 bytes (XYZ,XYM) or 32 bytes (XYZM) -You can force 3d geometries to be returned as 2d geometries by using the -force_2d() function. For example: +You can force geometries to be returned as 2d using the force_2d() +function. For example: - select wkb_ndr(force_2d(geom)) from mytable; + select asBinary(force_2d(geom)) from mytable; -If the client is running on a i386, you should use wkb_ndr() and on a sparc -you should use wkb_xdr() so you do not causes an endian shift on both the -server and client. +If the client is running on a i386, you should use asBinary(geom, 'NDR') +and on a sparc you should use asBinary(geom, 'XDR') so you do not causes +an endian shift on both the server and client.