在OpenGL环境下渲染shp文件，还能设置背景颜色。

/****************************************************************************** * $Id: shpopen.c,v 1.73 2012-01-24 22:33:01 fwarmerdam Exp $ * * Project: Shapelib * Purpose: Implementation of core Shapefile read/write functions. * Author: Frank Warmerdam, warmerdam@pobox.com * ****************************************************************************** * Copyright (c) 1999, 2001, Frank Warmerdam * * This software is available under the following "MIT Style" license, * or at the option of the licensee under the LGPL (see LICENSE.LGPL). This * option is discussed in more detail in shapelib.html. * * -- * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER * DEALINGS IN THE SOFTWARE. ****************************************************************************** * * $Log: shpopen.c,v $ * Revision 1.73 2012-01-24 22:33:01 fwarmerdam * fix memory leak on failure to open .shp (gdal #4410) * * Revision 1.72 2011-12-11 22:45:28 fwarmerdam * fix failure return from SHPOpenLL. * * Revision 1.71 2011-09-15 03:33:58 fwarmerdam * fix missing cast (#2344) * * Revision 1.70 2011-07-24 05:59:25 fwarmerdam * minimize use of CPLError in favor of SAHooks.Error() * * Revision 1.69 2011-07-24 03:24:22 fwarmerdam * fix memory leaks in error cases creating shapefiles (#2061) * * Revision 1.68 2010-08-27 23:42:52 fwarmerdam * add SHPAPI_CALL attribute in code * * Revision 1.67 2010-07-01 08:15:48 fwarmerdam * do not error out on an object with zero vertices * * Revision 1.66 2010-07-01 07:58:57 fwarmerdam * minor cleanup of error handling * * Revision 1.65 2010-07-01 07:27:13 fwarmerdam * white space formatting adjustments * * Revision 1.64 2010-01-28 11:34:34 fwarmerdam * handle the shape file length limits more gracefully (#3236) * * Revision 1.63 2010-01-28 04:04:40 fwarmerdam * improve numerical accuracy of SHPRewind() algs (gdal #3363) * * Revision 1.62 2010-01-17 05:34:13 fwarmerdam * Remove asserts on x/y being null (#2148). * * Revision 1.61 2010-01-16 05:07:42 fwarmerdam * allow 0/nulls in shpcreateobject (#2148) * * Revision 1.60 2009-09-17 20:50:02 bram * on Win32, define snprintf as alias to _snprintf * * Revision 1.59 2008-03-14 05:25:31 fwarmerdam * Correct crash on buggy geometries (gdal #2218) * * Revision 1.58 2008/01/08 23:28:26 bram * on line 2095, use a float instead of a double to avoid a compiler warning * * Revision 1.57 2007/12/06 07:00:25 fwarmerdam * dbfopen now using SAHooks for fileio * * Revision 1.56 2007/12/04 20:37:56 fwarmerdam * preliminary implementation of hooks api for io and errors * * Revision 1.55 2007/11/21 22:39:56 fwarmerdam * close shx file in readonly mode (GDAL #1956) * * Revision 1.54 2007/11/15 00:12:47 mloskot * Backported recent changes from GDAL (Ticket #1415) to Shapelib. * * Revision 1.53 2007/11/14 22:31:08 fwarmerdam * checks after mallocs to detect for corrupted/voluntary broken shapefiles. * http://trac.osgeo.org/gdal/ticket/1991 * * Revision 1.52 2007/06/21 15:58:33 fwarmerdam * fix for SHPRewindObject when rings touch at one vertex (gdal #976) * * Revision 1.51 2006/09/04 15:24:01 fwarmerdam * Fixed up log message for 1.49. * * Revision 1.50 2006/09/04 15:21:39 fwarmerdam * fix of last fix * * Revision 1.49 2006/09/04 15:21:00 fwarmerdam * MLoskot: Added stronger test of Shapefile reading failures, e.g. truncated * files. The problem was discovered by Tim Sutton and reported here * https://svn.qgis.org/trac/ticket/200 * * Revision 1.48 2006/01/26 15:07:32 fwarmerdam * add bMeasureIsUsed flag from Craig Bruce: Bug 1249 * * Revision 1.47 2006/01/04 20:07:23 fwarmerdam * In SHPWriteObject() make sure that the record length is updated * when rewriting an existing record. * * Revision 1.46 2005/02/11 17:17:46 fwarmerdam * added panPartStart[0] validation * * Revision 1.45 2004/09/26 20:09:48 fwarmerdam * const correctness changes * * Revision 1.44 2003/12/29 00:18:39 fwarmerdam * added error checking for failed IO and optional CPL error reporting * * Revision 1.43 2003/12/01 16:20:08 warmerda * be careful of zero vertex shapes * * Revision 1.42 2003/12/01 14:58:27 warmerda * added degenerate object check in SHPRewindObject() * * Revision 1.41 2003/07/08 15:22:43 warmerda * avoid warning * * Revision 1.40 2003/04/21 18:30:37 warmerda * added header write/update public methods * * Revision 1.39 2002/08/26 06:46:56 warmerda * avoid c++ comments * * Revision 1.38 2002/05/07 16:43:39 warmerda * Removed debugging printf. * * Revision 1.37 2002/04/10 17:35:22 warmerda * fixed bug in ring reversal code * * Revision 1.36 2002/04/10 16:59:54 warmerda * added SHPRewindObject * * Revision 1.35 2001/12/07 15:10:44 warmerda * fix if .shx fails to open * * Revision 1.34 2001/11/01 16:29:55 warmerda * move pabyRec into SHPInfo for thread safety * * Revision 1.33 2001/07/03 12:18:15 warmerda * Improved cleanup if SHX not found, provied by Riccardo Cohen. * * Revision 1.32 2001/06/22 01:58:07 warmerda * be more careful about establishing initial bounds in face of NULL shapes * * Revision 1.31 2001/05/31 19:35:29 warmerda * added support for writing null shapes * * Revision 1.30 2001/05/28 12:46:29 warmerda * Add some checking on reasonableness of record count when opening. * * Revision 1.29 2001/05/23 13:36:52 warmerda * added use of SHPAPI_CALL * * Revision 1.28 2001/02/06 22:25:06 warmerda * fixed memory leaks when SHPOpen() fails * * Revision 1.27 2000/07/18 15:21:33 warmerda * added better enforcement of -1 for append in SHPWriteObject * * Revision 1.26 2000/02/16 16:03:51 warmerda * added null shape support * * Revision 1.25 1999/12/15 13:47:07 warmerda * Fixed record size settings in .shp file (was 4 words too long) * Added stdlib.h. * * Revision 1.24 1999/11/05 14:12:04 warmerda * updated license terms * * Revision 1.23 1999/07/27 00:53:46 warmerda * added support for rewriting shapes * * Revision 1.22 1999/06/11 19:19:11 warmerda * Cleanup pabyRec static buffer on SHPClose(). * * Revision 1.21 1999/06/02 14:57:56 kshih * Remove unused variables * * Revision 1.20 1999/04/19 21:04:17 warmerda * Fixed syntax error. * * Revision 1.19 1999/04/19 21:01:57 warmerda * Force access string to binary in SHPOpen(). * * Revision 1.18 1999/04/01 18:48:07 warmerda * Try upper case extensions if lower case doesn't work. * * Revision 1.17 1998/12/31 15:29:39 warmerda * Disable writing measure values to multipatch objects if * DISABLE_MULTIPATCH_MEASURE is defined. * * Revision 1.16 1998/12/16 05:14:33 warmerda * Added support to write MULTIPATCH. Fixed reading Z coordinate of * MULTIPATCH. Fixed record size written for all feature types. * * Revision 1.15 1998/12/03 16:35:29 warmerda * r+b is proper binary access string, not rb+. * * Revision 1.14