monotonechainindexer.cpp

在Linux下做的QuadTree的程序

/**********************************************************************
 * $Id: MonotoneChainIndexer.cpp 1820 2006-09-06 16:54:23Z mloskot $
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.refractions.net
 *
 * Copyright (C) 2005-2006 Refractions Research Inc.
 * Copyright (C) 2001-2002 Vivid Solutions Inc.
 *
 * This is free software; you can redistribute and/or modify it under
 * the terms of the GNU Lesser General Public Licence as published
 * by the Free Software Foundation. 
 * See the COPYING file for more information.
 *
 **********************************************************************/

#include <vector>

#include <geos/geomgraph/index/MonotoneChainIndexer.h>
#include <geos/geom/Coordinate.h>
#include <geos/geom/CoordinateSequence.h>
#include <geos/geomgraph/Quadrant.h>

using namespace std;
using namespace geos::geom;

namespace geos {
namespace geomgraph { // geos.geomgraph
namespace index { // geos.geomgraph.index

void
MonotoneChainIndexer::getChainStartIndices(const CoordinateSequence* pts,
	vector<int> &startIndexList)
{
	// find the startpoint (and endpoints) of all monotone chains
	// in this edge
	int start=0;
	//vector<int>* startIndexList=new vector<int>();
	startIndexList.push_back(start);
	do {
		int last=findChainEnd(pts,start);
		startIndexList.push_back(last);
		start=last;
	} while(start<(int)pts->getSize()-1);
	// copy list to an array of ints, for efficiency
	//return startIndexList;
}

/**
* @return the index of the last point in the monotone chain
*/
int MonotoneChainIndexer::findChainEnd(const CoordinateSequence* pts,int start){
	// determine quadrant for chain
	int chainQuad=Quadrant::quadrant(pts->getAt(start),pts->getAt(start + 1));
	int last=start+1;
	while(last<(int)pts->getSize()) {
		// compute quadrant for next possible segment in chain
		int quad=Quadrant::quadrant(pts->getAt(last - 1),pts->getAt(last));
		if (quad!=chainQuad) break;
		last++;
	}
	return last-1;
}

} // namespace geos.geomgraph.index
} // namespace geos.geomgraph
} // namespage geos

/**********************************************************************
 * $Log$
 * Revision 1.9  2006/03/15 17:16:31  strk
 * streamlined headers inclusion
 *
 * Revision 1.8  2006/03/09 16:46:47  strk
 * geos::geom namespace definition, first pass at headers split
 *
 * Revision 1.7  2006/03/03 10:46:21  strk
 * Removed 'using namespace' from headers, added missing headers in .cpp files, removed useless includes in headers (bug#46)
 *
 * Revision 1.6  2006/02/19 19:46:49  strk
 * Packages <-> namespaces mapping for most GEOS internal code (uncomplete, but working). Dir-level libs for index/ subdirs.
 *
 * Revision 1.5  2006/01/31 19:07:34  strk
 * - Renamed DefaultCoordinateSequence to CoordinateArraySequence.
 * - Moved GetNumGeometries() and GetGeometryN() interfaces
 *   from GeometryCollection to Geometry class.
 * - Added getAt(int pos, Coordinate &to) funtion to CoordinateSequence class.
 * - Reworked automake scripts to produce a static lib for each subdir and
 *   then link all subsystem's libs togheter
 * - Moved C-API in it's own top-level dir capi/
 * - Moved source/bigtest and source/test to tests/bigtest and test/xmltester
 * - Fixed PointLocator handling of LinearRings
 * - Changed CoordinateArrayFilter to reduce memory copies
 * - Changed UniqueCoordinateArrayFilter to reduce memory copies
 * - Added CGAlgorithms::isPointInRing() version working with
 *   Coordinate::ConstVect type (faster!)
 * - Ported JTS-1.7 version of ConvexHull with big attention to
 *   memory usage optimizations.
 * - Improved XMLTester output and user interface
 * - geos::geom::util namespace used for geom/util stuff
 * - Improved memory use in geos::geom::util::PolygonExtractor
 * - New ShortCircuitedGeometryVisitor class
 * - New operation/predicate package
 *
 * Revision 1.4  2005/11/15 10:04:37  strk
 *
 * Reduced heap allocations (vectors, mostly).
 * Enforced const-correctness, changed some interfaces
 * to use references rather then pointers when appropriate.
 *
 * Revision 1.3  2004/07/08 19:34:49  strk
 * Mirrored JTS interface of CoordinateSequence, factory and
 * default implementations.
 * Added CoordinateArraySequenceFactory::instance() function.
 *
 * Revision 1.2  2004/07/02 13:28:26  strk
 * Fixed all #include lines to reflect headers layout change.
 * Added client application build tips in README.
 *
 * Revision 1.1  2004/04/14 06:04:26  ybychkov
 * "geomgraph/index" committ problem fixed.
 *
 * Revision 1.10  2004/03/19 09:49:29  ybychkov
 * "geomgraph" and "geomgraph/indexl" upgraded to JTS 1.4
 *
 * Revision 1.9  2003/11/07 01:23:42  pramsey
 * Add standard CVS headers licence notices and copyrights to all cpp and h
 * files.
 *
 * Revision 1.8  2003/10/15 16:39:03  strk
 * Made Edge::getCoordinates() return a 'const' value. Adapted code set.
 *
 **********************************************************************/