void Sable::scanParticle(QPointF p)
{
    QVector<Particle>::iterator itP;
        for (itP = particles.begin(); itP != particles.end(); ++itP)
        {
            if (qAbs(p.x() - itP->x()) < RAYON &&
                qAbs(p.y() - itP->y()) < RAYON)
            {
                QVector2D dir = QVector2D(p.x() - itP->x(),
                                          p.y() - itP->y());
                double dist = dir.length();
                if (dist < RAYON)
                {
                    dir.normalize();
                    QVector2D deltaPos = 3*dir*(RAYON-dist);
                    itP->setX(itP->x() - deltaPos.x());
                    itP->setY(itP->y() - deltaPos.y());
                }
            }
        }

        this->update();
}



void Particle::drawSand(const QVector<Particle> &ps)
{
    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(2, GL_DOUBLE, sizeof(Particle), &(ps[0].m_x));
    glEnableClientState(GL_COLOR_ARRAY);
    glColorPointer(3, GL_DOUBLE, sizeof(Particle), &(ps[0].r));
    glDrawArrays(GL_POINTS, 0, ps.count());
}