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/**********************************************************************
* $Id: RightmostEdgeFinder.cpp,v 1.9 2004/07/08 19:34:49 strk Exp $
*
* GEOS - Geometry Engine Open Source
* http://geos.refractions.net
*
* 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.
*
**********************************************************************
* $Log: RightmostEdgeFinder.cpp,v $
* Revision 1.9 2004/07/08 19:34:49 strk
* Mirrored JTS interface of CoordinateSequence, factory and
* default implementations.
* Added DefaultCoordinateSequenceFactory::instance() function.
*
* Revision 1.8 2004/07/02 13:28:28 strk
* Fixed all #include lines to reflect headers layout change.
* Added client application build tips in README.
*
* Revision 1.7 2004/04/10 08:40:01 ybychkov
* "operation/buffer" upgraded to JTS 1.4
*
* Revision 1.6 2003/11/07 01:23:42 pramsey
* Add standard CVS headers licence notices and copyrights to all cpp and h
* files.
*
* Revision 1.5 2003/10/15 16:39:03 strk
* Made Edge::getCoordinates() return a 'const' value. Adapted code set.
*
**********************************************************************/
#include <geos/opBuffer.h>
#include <geos/util.h>
namespace geos {
RightmostEdgeFinder::RightmostEdgeFinder(CGAlgorithms *newCga){
cga=newCga;
minIndex=-1;
minDe=NULL;
orientedDe=NULL;
minCoord.setNull();
}
DirectedEdge* RightmostEdgeFinder::getEdge() {
return orientedDe;
}
Coordinate& RightmostEdgeFinder::getCoordinate() {
return minCoord;
}
void RightmostEdgeFinder::findEdge(vector<DirectedEdge*>* dirEdgeList){
/**
* Check all forward DirectedEdges only. This is still general,
* because each edge has a forward DirectedEdge.
*/
for(int i=0;i<(int)dirEdgeList->size();i++) {
DirectedEdge *de=(*dirEdgeList)[i];
if (!de->isForward())
continue;
checkForRightmostCoordinate(de);
}
/**
* If the rightmost point is a node, we need to identify which of
* the incident edges is rightmost.
*/
Assert::isTrue(minIndex!=0 || minCoord==minDe->getCoordinate(), "inconsistency in rightmost processing");
if (minIndex==0 ) {
findRightmostEdgeAtNode();
} else {
findRightmostEdgeAtVertex();
}
/**
* now check that the extreme side is the R side.
* If not, use the sym instead.
*/
orientedDe=minDe;
int rightmostSide=getRightmostSide(minDe,minIndex);
if (rightmostSide==Position::LEFT) {
orientedDe=minDe->getSym();
}
}
void RightmostEdgeFinder::findRightmostEdgeAtNode(){
Node *node=minDe->getNode();
DirectedEdgeStar *star=(DirectedEdgeStar*) node->getEdges();
minDe=star->getRightmostEdge();
// the DirectedEdge returned by the previous call is not
// necessarily in the forward direction. Use the sym edge if it isn't.
if (!minDe->isForward()) {
minDe=minDe->getSym();
minIndex=minDe->getEdge()->getCoordinates()->getSize()-1;
}
}
void RightmostEdgeFinder::findRightmostEdgeAtVertex() {
/**
* The rightmost point is an interior vertex, so it has a segment on either side of it.
* If these segments are both above or below the rightmost point, we need to
* determine their relative orientation to decide which is rightmost.
*/
const CoordinateSequence *pts=minDe->getEdge()->getCoordinates();
Assert::isTrue(minIndex>0 && minIndex<pts->getSize(), "rightmost point expected to be interior vertex of edge");
const Coordinate& pPrev=pts->getAt(minIndex-1);
const Coordinate& pNext=pts->getAt(minIndex+1);
int orientation=cga->computeOrientation(minCoord,pNext,pPrev);
bool usePrev=false;
// both segments are below min point
if (pPrev.y<minCoord.y && pNext.y<minCoord.y
&& orientation==CGAlgorithms::COUNTERCLOCKWISE) {
usePrev=true;
} else if (pPrev.y>minCoord.y && pNext.y>minCoord.y
&& orientation==CGAlgorithms::CLOCKWISE) {
usePrev=true;
}
// if both segments are on the same side, do nothing - either is safe
// to select as a rightmost segment
if (usePrev) {
minIndex=minIndex-1;
}
}
void RightmostEdgeFinder::checkForRightmostCoordinate(DirectedEdge *de) {
const CoordinateSequence *coord=de->getEdge()->getCoordinates();
// only check vertices which are the starting point of a non-horizontal segment
for(int i=0;i<coord->getSize()-1;i++) {
// only check vertices which are the start or end point of a non-horizontal segment
// <FIX> MD 19 Sep 03 - NO! we can test all vertices, since the rightmost must have a non-horiz segment adjacent to it
if (minCoord==Coordinate::getNull() || coord->getAt(i).x>minCoord.x ) {
minDe=de;
minIndex=i;
minCoord=coord->getAt(i);
}
}
}
int RightmostEdgeFinder::getRightmostSide(DirectedEdge *de, int index){
int side=getRightmostSideOfSegment(de,index);
if (side<0)
side=getRightmostSideOfSegment(de,index-1);
if (side<0)
// reaching here can indicate that segment is horizontal
// Assert::shouldNeverReachHere("problem with finding rightmost side of segment");
minCoord=Coordinate::nullCoord;
checkForRightmostCoordinate(de);
return side;
}
int RightmostEdgeFinder::getRightmostSideOfSegment(DirectedEdge *de, int i){
Edge *e=de->getEdge();
const CoordinateSequence *coord=e->getCoordinates();
if (i<0 || i+1>=coord->getSize()) return -1;
if (coord->getAt(i).y==coord->getAt(i+1).y) return -1; // indicates edge is parallel to x-axis
int pos=Position::LEFT;
if (coord->getAt(i).y<coord->getAt(i+1).y) pos=Position::RIGHT;
return pos;
}
}
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