[CC]手动点云分割

CloudCompare中手动点云分割功能ccGraphicalSegmentationTool，

点击应用按钮后将现有的点云分成segmented和remaining两个点云，

//停用点云分割功能

void MainWindow::deactivateSegmentationMode(bool state)

是通过ccPointCloud的可视选择集来实现的。其中用到了点云的swap需要参考！

//创建新的点云，可视的选择集
ccGenericPointCloud* ccPointCloud::createNewCloudFromVisibilitySelection(bool removeSelectedPoints)
{
  if (!isVisibilityTableInstantiated())
  {
    ccLog::Error(QString("[Cloud %1] Visibility table not instantiated!").arg(getName()));
    return 0;
  }

  //we create a new cloud with the "visible" points
  ccPointCloud* result = 0;
  {
    //we create a temporary entity with the visible points only
    CCLib::ReferenceCloud* rc = getTheVisiblePoints();
    if (!rc)
    {
      //a warning message has already been issued by getTheVisiblePoints!
      //ccLog::Warning("[ccPointCloud::createNewCloudFromVisibilitySelection] An error occurred during points selection!");
      return 0;
    }
    assert(rc->size() != 0);

    //convert selection to cloud
    result = partialClone(rc);

    //don't need this one anymore
    delete rc;
    rc = 0;
  }

  if (!result)
  {
    ccLog::Warning("[ccPointCloud::createNewCloudFromVisibilitySelection] An error occurred during segmentation!");
    return 0;
  }

  result->setName(getName()+QString(".segmented"));//切割出来的点云

  //shall the visible points be erased from this cloud?
  if (removeSelectedPoints && !isLocked())
  {
    //we drop the octree before modifying this cloud's contents
    deleteOctree();
    clearLOD();

    unsigned count = size();

    //we have to take care of scan grids first
    {
      //we need a map between old and new indexes
      std::vector<int> newIndexMap(size(), -1);
      {
        unsigned newIndex = 0;
        for (unsigned i=0; i<count; ++i)
        {
          if (m_pointsVisibility->getValue(i) != POINT_VISIBLE)
            newIndexMap[i] = newIndex++;
        }
      }

      //then update the indexes
      UpdateGridIndexes(newIndexMap, m_grids);

      //and reset the invalid (empty) ones
      //(DGM: we don't erase them as they may still be useful?)
      for (size_t i=0; i<m_grids.size(); ++i)
      {
        Grid::Shared& scanGrid = m_grids[i];
        if (scanGrid->validCount == 0)
        {
          scanGrid->indexes.clear();
        }
      }
    }

    //we remove all visible points
    unsigned lastPoint = 0;
    for (unsigned i=0; i<count; ++i)
    {
      //i持续增长，而lastPoint遇到==POINT_VISIBLE则跳过，起到迁移的效果
      if (m_pointsVisibility->getValue(i) != POINT_VISIBLE)
      {
        if (i != lastPoint)
          swapPoints(lastPoint,i);
        ++lastPoint;
      }
    }

    //TODO: handle associated meshes

    resize(lastPoint);

    refreshBB(); //calls notifyGeometryUpdate + releaseVBOs
  }

  return result;
}

　　调用的方法getTheVisiblePoints()

CCLib::ReferenceCloud* ccGenericPointCloud::getTheVisiblePoints() const
{
  unsigned count = size();
  assert(count == m_pointsVisibility->currentSize());

  if (!m_pointsVisibility || m_pointsVisibility->currentSize() != count)
  {
    ccLog::Warning("[ccGenericPointCloud::getTheVisiblePoints] No visibility table instantiated!");
    return 0;
  }

  //count the number of points to copy
  unsigned pointCount = 0;
  {
    for (unsigned i=0; i<count; ++i)
      if (m_pointsVisibility->getValue(i) == POINT_VISIBLE)
        ++pointCount;
  }

  if (pointCount == 0)
  {
    ccLog::Warning("[ccGenericPointCloud::getTheVisiblePoints] No point in selection");
    return 0;
  }

  //we create an entity with the 'visible' vertices only
  CCLib::ReferenceCloud* rc = new CCLib::ReferenceCloud(const_cast<ccGenericPointCloud*>(this));
  if (rc->reserve(pointCount))
  {
    for (unsigned i=0; i<count; ++i)
      if (m_pointsVisibility->getValue(i) == POINT_VISIBLE)
        rc->addPointIndex(i); //can't fail (see above)
  }
  else
  {
    delete rc;
    rc = 0;
    ccLog::Error("[ccGenericPointCloud::getTheVisiblePoints] Not enough memory!");
  }

  return rc;
}