C++ QuadEdge::orig方法代码示例

QuadEdge& IncrementalDelaunayTriangulator::insertSite(const Vertex &v)
{
	/**
	 * This code is based on Guibas and Stolfi (1985), with minor modifications
	 * and a bug fix from Dani Lischinski (Graphic Gems 1993). (The modification
	 * I believe is the test for the inserted site falling exactly on an
	 * existing edge. Without this test zero-width triangles have been observed
	 * to be created)
	 */
	QuadEdge *e = subdiv->locate(v);

	if(!e) {
		throw LocateFailureException("");
	}

	if (subdiv->isVertexOfEdge(*e, v)) {
		// point is already in subdivision.
		return *e; 
	} 
	else if (subdiv->isOnEdge(*e, v.getCoordinate())) {
		// the point lies exactly on an edge, so delete the edge 
		// (it will be replaced by a pair of edges which have the point as a vertex)
		e = &e->oPrev();
		subdiv->remove(e->oNext());
	}

	/**
	 * Connect the new point to the vertices of the containing triangle 
	 * (or quadrilateral, if the new point fell on an existing edge.)
	 */
	QuadEdge* base = &subdiv->makeEdge(e->orig(), v);

	QuadEdge::splice(*base, *e);
	QuadEdge *startEdge = base;
	do {
		base = &subdiv->connect(*e, base->sym());
		e = &base->oPrev();
	} while (&e->lNext() != startEdge);


	// Examine suspect edges to ensure that the Delaunay condition
	// is satisfied.
	do {
		QuadEdge* t = &e->oPrev();
		if (t->dest().rightOf(*e) &&
				v.isInCircle(e->orig(), t->dest(), e->dest())) {
			QuadEdge::swap(*e);
			e = &e->oPrev();
		} else if (&e->oNext() == startEdge) {
			return *base; // no more suspect edges.
		} else {
			e = &e->oNext().lPrev();
		}
	} while (true);
}

std::auto_ptr<QuadEdge>
QuadEdge::connect(QuadEdge &a, QuadEdge &b) 
{
	std::auto_ptr<QuadEdge> q0 = makeEdge(a.dest(), b.orig());
	splice(*q0, a.lNext());
	splice(q0->sym(), b);
	return q0;
}

bool
QuadEdge::equalsOriented(const QuadEdge &qe) const
{
	if (orig().getCoordinate().equals2D(qe.orig().getCoordinate())
			&& dest().getCoordinate().equals2D(qe.dest().getCoordinate()))
		return true;
	return false;
}

bool Vertex::leftOf(const QuadEdge &e) const {
	return isCCW(e.orig(), e.dest());
}