C++ TPPLPoly::GetNumPoints方法代码示例

std::vector<sf::Vector2f> _getEdges(TPPLPoly& A)
{
	std::vector<sf::Vector2f> edges;
	for(unsigned int i=0; i < (A.GetNumPoints()+1) ; ++i)
	{
		sf::Vector2f P1( A[i].x, A[i].y);
		sf::Vector2f P2( A[(i+1)%A.GetNumPoints()].x, A[(i+1)%A.GetNumPoints()].y );

		edges.push_back( P2 - P1 );
	}
	return edges;
}

std::vector<sf::Vector2f> _getPoints(TPPLPoly& A)
{
	std::vector<sf::Vector2f> points;
	for(unsigned int i=0; i < A.GetNumPoints() ; ++i)
	{
		sf::Vector2f P( A[i].x, A[i].y);

		points.push_back( P );
	}
	return points;
}

//triangulates a set of polygons by first partitioning them into monotone polygons
//O(n*log(n)) time complexity, O(n) space complexity
//the algorithm used here is outlined in the book
//"Computational Geometry: Algorithms and Applications" 
//by Mark de Berg, Otfried Cheong, Marc van Kreveld and Mark Overmars
int TPPLPartition::MonotonePartition(list<TPPLPoly> *inpolys, list<TPPLPoly> *monotonePolys) {
	list<TPPLPoly>::iterator iter;
	MonotoneVertex *vertices;
	long i,numvertices,vindex,vindex2,newnumvertices,maxnumvertices;
	long polystartindex, polyendindex;
	TPPLPoly *poly;
	MonotoneVertex *v,*v2,*vprev,*vnext;
	ScanLineEdge newedge;
	bool error = false;

	numvertices = 0;
	for(iter = inpolys->begin(); iter != inpolys->end(); iter++) {
		numvertices += iter->GetNumPoints();
	}

	maxnumvertices = numvertices*3;
	vertices = new MonotoneVertex[maxnumvertices];
	newnumvertices = numvertices;

	polystartindex = 0;
	for(iter = inpolys->begin(); iter != inpolys->end(); iter++) {
		poly = &(*iter);
		polyendindex = polystartindex + poly->GetNumPoints()-1;
		for(i=0;i<poly->GetNumPoints();i++) {
			vertices[i+polystartindex].p = poly->GetPoint(i);
			if(i==0) vertices[i+polystartindex].previous = polyendindex;
			else vertices[i+polystartindex].previous = i+polystartindex-1;
			if(i==(poly->GetNumPoints()-1)) vertices[i+polystartindex].next = polystartindex;
			else vertices[i+polystartindex].next = i+polystartindex+1;
		}
		polystartindex = polyendindex+1;
	}

	//construct the priority queue
	long *priority = new long [numvertices];
	for(i=0;i<numvertices;i++) priority[i] = i;
	std::sort(priority,&(priority[numvertices]),VertexSorter(vertices));

	//determine vertex types
	char *vertextypes = new char[maxnumvertices];
	for(i=0;i<numvertices;i++) {
		v = &(vertices[i]);
		vprev = &(vertices[v->previous]);
		vnext = &(vertices[v->next]);

		if(Below(vprev->p,v->p)&&Below(vnext->p,v->p)) {
			if(IsConvex(vnext->p,vprev->p,v->p)) {
				vertextypes[i] = TPPL_VERTEXTYPE_START;
			} else {
				vertextypes[i] = TPPL_VERTEXTYPE_SPLIT;
			}
		} else if(Below(v->p,vprev->p)&&Below(v->p,vnext->p)) {
			if(IsConvex(vnext->p,vprev->p,v->p))
			{
				vertextypes[i] = TPPL_VERTEXTYPE_END;
			} else {
				vertextypes[i] = TPPL_VERTEXTYPE_MERGE;
			}
		} else {
			vertextypes[i] = TPPL_VERTEXTYPE_REGULAR;
		}
	}

	//helpers
	long *helpers = new long[maxnumvertices];

	//binary search tree that holds edges intersecting the scanline
	//note that while set doesn't actually have to be implemented as a tree
	//complexity requirements for operations are the same as for the balanced binary search tree
	set<ScanLineEdge> edgeTree;
	//store iterators to the edge tree elements
	//this makes deleting existing edges much faster
	set<ScanLineEdge>::iterator *edgeTreeIterators,edgeIter;
	edgeTreeIterators = new set<ScanLineEdge>::iterator[maxnumvertices];
	pair<set<ScanLineEdge>::iterator,bool> edgeTreeRet;
	for(i = 0; i<numvertices; i++) edgeTreeIterators[i] = edgeTree.end();

	//for each vertex
	for(i=0;i<numvertices;i++) {
		vindex = priority[i];
		v = &(vertices[vindex]);
		vindex2 = vindex;
		v2 = v;

		//depending on the vertex type, do the appropriate action
		//comments in the following sections are copied from "Computational Geometry: Algorithms and Applications"
		switch(vertextypes[vindex]) {
			case TPPL_VERTEXTYPE_START:
				//Insert ei in T and set helper(ei) to vi.
				newedge.p1 = v->p;
				newedge.p2 = vertices[v->next].p;
				newedge.index = vindex;
				edgeTreeRet = edgeTree.insert(newedge);
				edgeTreeIterators[vindex] = edgeTreeRet.first;
				helpers[vindex] = vindex;
//.........这里部分代码省略.........