HalfEdgeList.h

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#include "DCELHalfEdge.h"
#include "DCELVertex.h"
#include "FaceList.h"


using namespace std;
class HalfEdgeList
{
public:
    HalfEdgeList(void);
    ~HalfEdgeList(void);

    DCELHalfEdge* head;
    DCELHalfEdge* tail;
    int globalEdgeCount;

    void addToList(DCELHalfEdge* newEdge);
    void removeFromList(DCELHalfEdge* edge);
    DCELHalfEdge* addTwinTo(DCELHalfEdge* edge, DCELHalfEdge* LaggingTwin);
    DCELFace* addEdgeBetween(DCELVertex* v1, DCELVertex* v2, DCELFace* face);
protected:
    bool status;
};

HalfEdgeList::HalfEdgeList(void) : globalEdgeCount(0), head(NULL), tail(NULL), status(false)
{
}

HalfEdgeList::~HalfEdgeList(void)
{
}

void HalfEdgeList::addToList(DCELHalfEdge* newEdge)
{
    newEdge->meta = ++globalEdgeCount;

    if (head)
    {
        tail->next = newEdge;
        tail = newEdge;
    }
    else {
        head = newEdge;
        tail = newEdge;
    }
}

DCELHalfEdge* HalfEdgeList::addTwinTo(DCELHalfEdge* edge, DCELHalfEdge* LaggingTwin) {
    DCELHalfEdge *twinEdge = new DCELHalfEdge();
    twinEdge->meta = ++globalEdgeCount;
    twinEdge->twin = edge;
    if (LaggingTwin) {
        LaggingTwin->origin = twinEdge->twin->origin;
        twinEdge->next = LaggingTwin;
    }
    edge->twin = twinEdge;
    return twinEdge;
}

void HalfEdgeList::removeFromList(DCELHalfEdge* edge)
{
    edge->getPrev()->next = edge->twin->next;
    edge->twin->getPrev()->next = edge->next;
    delete edge->twin;
    delete edge;
}

DCELFace* HalfEdgeList::addEdgeBetween(DCELVertex* v1, DCELVertex* v2, DCELFace* face)
{
    DCELHalfEdge* walker = face->edge;
    while (1) {
        if (walker->next->origin == v1)
            break;
        walker = walker->next;
    }

    DCELHalfEdge* halfEdge = new DCELHalfEdge();
    halfEdge->origin = v2;
    halfEdge->meta = ++globalEdgeCount;
    halfEdge->next = walker->next;
    
    DCELHalfEdge* twinWalker = face->edge;
    while (1) {
        if (twinWalker->next->origin == v2)
            break;
        twinWalker = twinWalker->next;
    }

    DCELHalfEdge* twinEdge = new DCELHalfEdge();
    twinEdge->origin = v1;
    twinEdge->meta = ++globalEdgeCount;
    twinEdge->next = twinWalker->next;
    
    walker->next = twinEdge;
    twinWalker->next = halfEdge;
    
    halfEdge->twin = twinEdge;
    twinEdge->twin = halfEdge;


    DCELFace* firstHalf = new DCELFace();
    firstHalf->edge = halfEdge;
    walker = halfEdge;
    do {
        walker->face = firstHalf;
        walker = walker->next;
    } while(walker != halfEdge);

    DCELFace* secHalf = new DCELFace();
    secHalf->edge = twinEdge;
    twinEdge->face = secHalf;
    walker = twinEdge;
    do {
        walker->face = secHalf;
        walker = walker->next;
    } while(walker != twinEdge);

    secHalf->next = firstHalf;
    return secHalf;
}