src/livarot/sweep-event.cpp

	sweep-event.cpp revision 05125af10a607ea488d4364d36378884c53b880b
#include <glib.h>
#include "livarot/sweep-event-queue.h"
#include "livarot/sweep-tree.h"
#include "livarot/sweep-event.h"
#include "livarot/Shape.h"

SweepEventQueue::SweepEventQueue(int s) : nbEvt(0), maxEvt(s)
{
    /* FIXME: use new[] for this, but this causes problems when delete[]
    ** calls the SweepEvent destructors.
    */
    events = (SweepEvent *) g_malloc(maxEvt * sizeof(SweepEvent));
    inds = new int[maxEvt];
}

SweepEventQueue::~SweepEventQueue()
{
    g_free(events);
    delete []inds;
}

SweepEvent *SweepEventQueue::add(SweepTree *iLeft, SweepTree *iRight, Geom::Point &px, double itl, double itr)
{
    if (nbEvt > maxEvt) {
    return NULL;
    }

    int const n = nbEvt++;
    events[n].MakeNew (iLeft, iRight, px, itl, itr);

    SweepTree *t[2] = { iLeft, iRight };
    for (int i = 0; i < 2; i++) {
        Shape *s = t[i]->src;
    Shape::dg_arete const &e = s->getEdge(t[i]->bord);
    int const n = std::max(e.st, e.en);
    s->pData[n].pending++;;
    }

    events[n].ind = n;
    inds[n] = n;

    int curInd = n;
    while (curInd > 0) {
    int const half = (curInd - 1) / 2;
    int const no = inds[half];
    if (px[1] < events[no].posx[1]
        || (px[1] == events[no].posx[1] && px[0] < events[no].posx[0]))
    {
        events[n].ind = half;
        events[no].ind = curInd;
        inds[half] = n;
        inds[curInd] = no;
    } else {
        break;
    }

    curInd = half;
    }

    return events + n;
}


bool SweepEventQueue::peek(SweepTree * &iLeft, SweepTree * &iRight, Geom::Point &px, double &itl, double &itr)
{
    if (nbEvt <= 0) {
    return false;
    }

    SweepEvent const &e = events[inds[0]];

    iLeft = e.sweep[LEFT];
    iRight = e.sweep[RIGHT];
    px = e.posx;
    itl = e.tl;
    itr = e.tr;

    return true;
}

bool SweepEventQueue::extract(SweepTree * &iLeft, SweepTree * &iRight, Geom::Point &px, double &itl, double &itr)
{
    if (nbEvt <= 0) {
    return false;
    }

    SweepEvent &e = events[inds[0]];

    iLeft = e.sweep[LEFT];
    iRight = e.sweep[RIGHT];
    px = e.posx;
    itl = e.tl;
    itr = e.tr;
    remove(&e);

    return true;
}


void SweepEventQueue::remove(SweepEvent *e)
{
    if (nbEvt <= 1) {
    e->MakeDelete ();
    nbEvt = 0;
    return;
    }

    int const n = e->ind;
    int to = inds[n];
    e->MakeDelete();
    relocate(&events[--nbEvt], to);

    int const moveInd = nbEvt;
    if (moveInd == n) {
    return;
    }

    to = inds[moveInd];

    events[to].ind = n;
    inds[n] = to;

    int curInd = n;
    Geom::Point const px = events[to].posx;
    bool didClimb = false;
    while (curInd > 0) {
    int const half = (curInd - 1) / 2;
    int const no = inds[half];
    if (px[1] < events[no].posx[1]
        || (px[1] == events[no].posx[1] && px[0] < events[no].posx[0]))
    {
      events[to].ind = half;
      events[no].ind = curInd;
      inds[half] = to;
      inds[curInd] = no;
      didClimb = true;
    } else {
        break;
    }
    curInd = half;
    }

    if (didClimb) {
    return;
    }

    while (2 * curInd + 1 < nbEvt) {
    int const child1 = 2 * curInd + 1;
    int const child2 = child1 + 1;
    int const no1 = inds[child1];
    int const no2 = inds[child2];
    if (child2 < nbEvt) {
        if (px[1] > events[no1].posx[1]
        || (px[1] == events[no1].posx[1]
            && px[0] > events[no1].posx[0]))
        {
        if (events[no2].posx[1] > events[no1].posx[1]
            || (events[no2].posx[1] == events[no1].posx[1]
            && events[no2].posx[0] > events[no1].posx[0]))
        {
            events[to].ind = child1;
            events[no1].ind = curInd;
            inds[child1] = to;
            inds[curInd] = no1;
            curInd = child1;
        } else {
            events[to].ind = child2;
            events[no2].ind = curInd;
            inds[child2] = to;
            inds[curInd] = no2;
            curInd = child2;
        }
        } else {
        if (px[1] > events[no2].posx[1]
            || (px[1] == events[no2].posx[1]
            && px[0] > events[no2].posx[0]))
        {
            events[to].ind = child2;
            events[no2].ind = curInd;
            inds[child2] = to;
            inds[curInd] = no2;
            curInd = child2;
        } else {
            break;
        }
        }
    } else {
        if (px[1] > events[no1].posx[1]
        || (px[1] == events[no1].posx[1]
            && px[0] > events[no1].posx[0]))
        {
        events[to].ind = child1;
        events[no1].ind = curInd;
        inds[child1] = to;
        inds[curInd] = no1;
        }

        break;
    }
    }
}


void SweepEventQueue::relocate(SweepEvent *e, int to)
{
    if (inds[e->ind] == to) {
    return;         // j'y suis deja
    }

    events[to] = *e;

    e->sweep[LEFT]->evt[RIGHT] = events + to;
    e->sweep[RIGHT]->evt[LEFT] = events + to;
    inds[e->ind] = to;
}


/*
 * a simple binary heap
 * it only contains intersection events
 * the regular benley-ottman stuffs the segment ends in it too, but that not needed here since theses points
 * are already sorted. and the binary heap is much faster with only intersections...
 * the code sample on which this code is based comes from purists.org
 */
SweepEvent::SweepEvent()
{
    MakeNew (NULL, NULL, Geom::Point(0, 0), 0, 0);
}

SweepEvent::~SweepEvent()
{
    MakeDelete();
}

void SweepEvent::MakeNew(SweepTree *iLeft, SweepTree *iRight, Geom::Point const &px, double itl, double itr)
{
    ind = -1;
    posx = px;
    tl = itl;
    tr = itr;
    sweep[LEFT] = iLeft;
    sweep[RIGHT] = iRight;
    sweep[LEFT]->evt[RIGHT] = this;
    sweep[RIGHT]->evt[LEFT] = this;
}

void SweepEvent::MakeDelete()
{
    for (int i = 0; i < 2; i++) {
    if (sweep[i]) {
        Shape *s = sweep[i]->src;
        Shape::dg_arete const &e = s->getEdge(sweep[i]->bord);
        int const n = std::max(e.st, e.en);
        s->pData[n].pending--;
    }

    sweep[i]->evt[1 - i] = NULL;
    sweep[i] = NULL;
    }
}


/*
  Local Variables:
  mode:c++
  c-file-style:"stroustrup"
  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
  indent-tabs-mode:nil
  fill-column:99
  End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :