vtk displays rendering data process

Generally, vtk is divided into the following steps: Data Source (Source) → Data Filter (Filter) → Data Mapper (Mapper) → Actor → Renderer (Renderer) → Render Window (RenderWindow) → Interactor (Interactor), as follows A piece of code that completely uses the entire process. Generally, you can only use part of it, and some will default to it.

#include <pcl/io/pcd_io.h>
#include <pcl/point_types.h>
#include <pcl/filters/voxel_grid.h>
#include <pcl/visualization/pcl_visualizer.h>

int main(int argc, char** argv)
{
    
    
    // 读取点云数据
    pcl::PointCloud<pcl::PointXYZ>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZ>);
    pcl::PCDReader reader;
    reader.read("input.pcd", *cloud);

    // 数据过滤器：对点云进行下采样
    pcl::PointCloud<pcl::PointXYZ>::Ptr cloud_filtered(new pcl::PointCloud<pcl::PointXYZ>);
    pcl::VoxelGrid<pcl::PointXYZ> sor;
    sor.setInputCloud(cloud);
    sor.setLeafSize(0.01f, 0.01f, 0.01f);
    sor.filter(*cloud_filtered);

    // 数据映射器：将点云数据转换为渲染器可用的数据结构
    pcl::visualization::PointCloudColorHandler<pcl::PointXYZ> color(cloud_filtered);
    pcl::visualization::PointCloudGeometryHandler<pcl::PointXYZ> geometry(cloud_filtered);

    // Actor：将点云添加到渲染器的场景中，并设置属性
    pcl::visualization::PCLVisualizer viewer("PointCloud Viewer");
    viewer.setBackgroundColor(0.0, 0.0, 0.0);
    viewer.addCoordinateSystem(1.0);
    viewer.addPointCloud(cloud_filtered, color, "cloud");
    viewer.setPointCloudRenderingProperties(pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 1, "cloud");

    // 渲染器：设置相机、光源等属性，并生成最终的图像
    viewer.setCameraPosition(0, 0, -2, 0, -1, 0, 0);
    viewer.setCameraClipDistances(0.01, 10.0);
    viewer.setLightPosition(0, 0, -2, 0);
    viewer.spinOnce();

    // 渲染窗口：创建渲染窗口，并显示渲染结果
    pcl::visualization::PCLVisualizerInteractorStyle style;
    viewer.registerKeyboardCallback(&style, (void*)NULL);
    viewer.registerMouseCallback(&style, (void*)NULL);
    viewer.registerPointPickingCallback(&style, (void*)NULL);
    viewer.registerAreaPickingCallback(&style, (void*)NULL);
    viewer.registerKeyboardEventCallback(&style, (void*)NULL);
    viewer.registerMouseCallback(&style, (void*)NULL);
    viewer.registerPointPickingCallback(&style, (void*)NULL);
    viewer.registerAreaPickingCallback(&style, (void*)NULL);
    viewer.registerWindowResizeCallback(&style, (void*)NULL);
    viewer.spin();
    
    return 0;
}