[C++知识库]（二）单点选择并显示坐标

1、功能

鼠标左边+shift，选择点，在控制台输出点的坐标

2、代码示例

#include <pcl/visualization/cloud_viewer.h>  
#include <iostream>  
#include <pcl/io/io.h>  
#include <pcl/io/pcd_io.h>  

using namespace pcl;

typedef pcl::PointXYZ PointT;
typedef pcl::PointCloud<PointT> PointCloudT;

// Mutex: //进程锁
boost::mutex cloud_mutex;

//用于给回调函数的结构体定义
struct callback_args
{
	PointCloudT::Ptr clicked_points_3d;
	pcl::visualization::PCLVisualizer::Ptr viewerPtr;
};
//回调函数
//按住shift，鼠标右键点一下点云，会显示出点的距离
void pp_callback(const pcl::visualization::PointPickingEvent& event, void* args)
{
	struct callback_args* data = (struct callback_args*)args;
	if (event.getPointIndex() == -1)
		return;
	PointT current_point;
	event.getPoint(current_point.x, current_point.y, current_point.z);


	data->clicked_points_3d->clear();//将上次选的点清空
	data->clicked_points_3d->points.push_back(current_point);//添加新选择的点
	// Draw clicked points in red:将选中点用红色标记
	pcl::visualization::PointCloudColorHandlerCustom<PointT> red(data->clicked_points_3d, 255, 0, 0);
	data->viewerPtr->removePointCloud("clicked_points");
	data->viewerPtr->addPointCloud(data->clicked_points_3d, red, "clicked_points");
	data->viewerPtr->setPointCloudRenderingProperties(pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 10, "clicked_points");
	std::cout << current_point.x << " " << current_point.y << " " << current_point.z << std::endl;

}



int main()
{
	std::string incloudfile = "..\\dragon.pcd";

	PointCloud<PointXYZ>::Ptr cloud(new PointCloud<PointXYZ>);
	boost::shared_ptr<visualization::PCLVisualizer> viewer(new visualization::PCLVisualizer("3D viewer")); // 实例化PCLVisualizer对象，窗口命名为3D viewer
	pcl::io::loadPCDFile(incloudfile, *cloud);

	viewer->setBackgroundColor(0, 0, 0); // 设置背景颜色
	viewer->addPointCloud<PointXYZ>(cloud, "sample cloud");
	//viewer->setPointCloudRenderingProperties(visualization::PCL_VISUALIZER_OPACITY, 2, "sample cloud");// 设置点云显示属性，


	cloud_mutex.lock();
	//可视化窗口执行回调函数
	struct callback_args cb_args;
	PointCloudT::Ptr clicked_points_3d(new PointCloudT);
	cb_args.clicked_points_3d = clicked_points_3d;
	cb_args.viewerPtr = pcl::visualization::PCLVisualizer::Ptr(viewer);
	//注册屏幕选点事件
	viewer->registerPointPickingCallback(pp_callback, (void*)&cb_args);
	//Shfit+鼠标左键选择点
	std::cout << "Shift+click on three floor points, then press 'Q'..." << std::endl;

	// Spin until 'Q' is pressed:
	//摁“Q”键结束
	viewer->spin();
	//释放互斥体
	cloud_mutex.unlock();
	while (!viewer->wasStopped()) {
		viewer->spinOnce(100);
		boost::this_thread::sleep(boost::posix_time::microseconds(1000));
	}


	return 0;
}

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