C++ Intersections::begin方法代码示例

// This method performs intersection testing at the given XY coords, and returns true if
// any intersections were found. It will break after processing the first pickable Window
// it finds.
bool WindowManager::pickAtXY(float x, float y, WidgetList& wl)
{
    Intersections intr;


    osg::Camera* camera = _view->getCamera();
    osgViewer::GraphicsWindow* gw = dynamic_cast<osgViewer::GraphicsWindow*>(camera->getGraphicsContext());
    if (gw)
    {
        _view->computeIntersections(camera, osgUtil::Intersector::WINDOW, x, y, intr, _nodeMask);
    }

    if (!intr.empty())
    {
        // Get the first Window at the XY coordinates; if you want a Window to be
        // non-pickable, set the NodeMask to something else.
        Window* activeWin = 0;

        // Iterate over every picked result and create a list of Widgets that belong
        // to that Window.
        for(Intersections::iterator i = intr.begin(); i != intr.end(); i++) {
            Window* win = dynamic_cast<Window*>(i->nodePath.back()->getParent(0));

            // Make sure that our window is valid, and that our pick is within the
            // "visible area" of the Window.
            if(
                !win ||
                (win->getVisibilityMode() == Window::VM_PARTIAL && !win->isPointerXYWithinVisible(x, y))
            ) {
                continue;
            }

            // Set our activeWin, so that we know when we've got all the Widgets
            // that belong to it.
            if(!activeWin) activeWin = win;

            // If we've found a new Widnow, break out!
            else if(activeWin != win) break;

            Widget* widget = dynamic_cast<Widget*>(i->drawable.get());

            if(!widget) continue;

            // We need to return a list of every Widget that was picked, so
            // that the handler can operate on it accordingly.
            else wl.push_back(widget);
        }

        if(wl.size()) {
            // Potentially VERY expensive; only to be used for debugging. :)
            if(_flags & WM_PICK_DEBUG) _updatePickWindow(&wl, x, y);

            return true;
        }
    }

    if(_flags & WM_PICK_DEBUG) _updatePickWindow(0, x, y);

    return false;
}

void Scene::cut_segment_plane()
{
    // Build tree (if build fail, exit)
    build_facet_tree();
    if ( m_facet_tree.empty() ) {
        return;
    }

    Plane plane = frame_plane();

    // Compute intersections
    typedef std::vector<Facet_tree::Object_and_primitive_id> Intersections;
    Intersections intersections;
    m_facet_tree.all_intersections(plane, std::back_inserter(intersections));

    // Fill data structure
    m_cut_segments.clear();
    for ( Intersections::iterator it = intersections.begin(),
            end = intersections.end() ; it != end ; ++it )
    {
        const Segment* inter_seg = CGAL::object_cast<Segment>(&(it->first));

        if ( NULL != inter_seg )
        {
            m_cut_segments.push_back(*inter_seg);
        }
    }

    m_cut_plane = CUT_SEGMENTS;
}

void QTessellatorPrivate::processIntersections()
{
    QDEBUG() << "PROCESS INTERSECTIONS";
    // process intersections
    while (!intersections.isEmpty()) {
        Intersections::iterator it = intersections.begin();
        if (it.key().y != y)
            break;

        // swap edges
        QDEBUG() << "    swapping intersecting edges ";
        int min = scanline.size;
        int max = 0;
        Q27Dot5 xmin = INT_MAX;
        Q27Dot5 xmax = INT_MIN;
        int num = 0;
        while (1) {
            const Intersection &i = it.key();
            int next = it->next;

            int edgePos = scanline.findEdge(i.edge);
            if (edgePos >= 0) {
                ++num;
                min = qMin(edgePos, min);
                max = qMax(edgePos, max);
                Edge *edge = scanline.edges[edgePos];
                xmin = qMin(xmin, edge->positionAt(y));
                xmax = qMax(xmax, edge->positionAt(y));
            }
            Intersection key;
            key.y = y;
            key.edge = next;
            it = intersections.find(key);
            intersections.remove(i);
            if (it == intersections.end())
                break;
        }
        if (num < 2)
            continue;

        Q_ASSERT(min != max);
        QDEBUG() << "sorting between" << min << "and" << max << "xpos=" << xmin << xmax;
        while (min > 0 && scanline.edges[min - 1]->positionAt(y) >= xmin) {
            QDEBUG() << "    adding edge on left";
            --min;
        }
        while (max + 1 < scanline.size && scanline.edges[max + 1]->positionAt(y) <=  xmax) {
            QDEBUG() << "    adding edge on right";
            ++max;
        }

        qSort(scanline.edges + min, scanline.edges + max + 1, EdgeSorter(y));
#ifdef DEBUG
        for (int i = min; i <= max; ++i)
            QDEBUG() << "        " << scanline.edges[i]->edge << "at pos" << i;
#endif
        for (int i = min; i <= max; ++i) {
            Edge *edge = scanline.edges[i];
            edge->intersect_left = true;
            edge->intersect_right = true;
            edge->mark = true;
        }
    }
}