C++ Paths::at方法代码示例

void World::update(cv::Mat &homography)
{
    this->m_world->Step(dt, 10, 10);

    //check contacts
    std::vector<MyContact>::iterator pos;
    std::map<b2Body*, ClipperLib::Paths*> newBodyMap;
    std::vector<b2Body*> removeBarrierList;

    for(pos = this->m_contactListener->m_contacts.begin();
        pos != this->m_contactListener->m_contacts.end();
        ++pos)
    {
        MyContact contact = *pos;

        if ((contact.fixtureA == this->m_ballFixture || contact.fixtureB == this->m_ballFixture) 
            && (contact.fixtureA->GetBody() != m_groundBody && contact.fixtureB->GetBody() != m_groundBody)
            && (contact.fixtureA->GetBody() != m_paddlesBody && contact.fixtureB->GetBody() != m_paddlesBody))
        {
            b2Fixture* objectFixture = contact.fixtureA == this->m_ballFixture ? contact.fixtureB : contact.fixtureA;
            b2Body *objectBody = objectFixture->GetBody();

            if (objectFixture->GetType() == b2Shape::e_edge)
            {
                cv::Point2f hitPoint = CVUtils::transformPoint(cv::Point2f(contact.contactPoint->x * PTM_RATIO, contact.contactPoint->y * PTM_RATIO), homography);
                this->notifyBallHitObservers(hitPoint.x, hitPoint.y);

                // change the shape of the fixture
                // only go into processing if this body was not processed yet (possible ball hit two fixture of same body)
                if (newBodyMap.find(objectBody) == newBodyMap.end())
                {
                    ClipperLib::Paths* bodyPolygons = (ClipperLib::Paths*)objectBody->GetUserData();

                    b2Vec2* impactVelocity = contact.fixtureA == m_ballFixture ? contact.impactVelocityA : contact.impactVelocityB;
                    float ballAngle = atan2(impactVelocity->y, impactVelocity->x); // get the angle (in radians) the ball is moving to
                    float ballPower = impactVelocity->Length() * 0.5;    // get the "power" of the ball movement vector
                    float openingStepInRadians = 10 * CV_PI / 180;  // calculate the opening in radians

                    // create the clipping object/shape - a wedge from ball's center with 30 degree opening over ball direction (angle)
                    ClipperLib::Path clip;
                    clip.push_back(ClipperLib::IntPoint(contact.contactPoint->x * PTM_RATIO, contact.contactPoint->y * PTM_RATIO));

                    for(int step = 9; step > -10; step--)
                    {
                        float dx = cos(ballAngle + step * openingStepInRadians) * ballPower;
                        float dy = sin(ballAngle + step * openingStepInRadians) * ballPower;

                        clip.push_back(ClipperLib::IntPoint(contact.contactPoint->x * PTM_RATIO + dx, contact.contactPoint->y * PTM_RATIO + dy));
                    }

                    ClipperLib::Clipper clipper;
                    clipper.AddPaths((*bodyPolygons), ClipperLib::ptSubject, true);
                    clipper.AddPath(clip, ClipperLib::ptClip, true);

                    // the difference is the new polygon formed by the clipping (collision)
                    ClipperLib::Paths* newPolygons = new ClipperLib::Paths();
                    clipper.Execute(ClipperLib::ctDifference, (*newPolygons), ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);

                    // Save the new polygons of this body
                    objectBody->SetUserData(newPolygons);
                    newBodyMap[objectBody] = newPolygons;

                    // now, find the intersection regions - these should be inpainted to the scene
                    ClipperLib::Paths destroyedParts;
                    clipper.Execute(ClipperLib::ctIntersection, destroyedParts, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);

                    // paint the required areas to be coppied
                    for (size_t i = 0; i < destroyedParts.size(); i++)
                    {
                        cv::Point* points = new cv::Point[destroyedParts[i].size()];

                        for (size_t j = 0; j < destroyedParts[i].size(); j++)
                        {
                            points[j].x = (int)destroyedParts[i][j].X;
                            points[j].y = (int)destroyedParts[i][j].Y;
                        }

                        m_destroyedPolygons.push_back(points);
                        m_destroyedPolygonsPointCount.push_back((int)destroyedParts[i].size());
                    }
                }
            }
            else if (objectFixture->GetType() == b2Shape::e_circle)
            {
                // this is a barrier - add it to the remove list
                removeBarrierList.push_back(objectBody);
            }
        }
    }

    std::map<b2Body*, ClipperLib::Paths*>::iterator iter;

    for(iter = newBodyMap.begin(); iter != newBodyMap.end(); iter++)
    {
        b2Body* objectBody = iter->first;
        ClipperLib::Paths* newPolygons = iter->second;

        // remove all the current fixtures from this body
        for (b2Fixture* f = objectBody->GetFixtureList(); f; )
        {
//.........这里部分代码省略.........