VTK_Learning_把几何结构&拓扑结构加入到数据集

╰+攻爆jí腚メ 2023-06-28 04:53 27阅读 0赞

# 1. 无拓扑结构 #

> 只有几何结构，没有拓扑结构的vtkDataSet
> 
>     #include <vtkAutoInit.h>  
>     VTK_MODULE_INIT(vtkRenderingOpenGL); 
>      
>     #include <vtkSmartPointer.h>
>     #include <vtkPointData.h>
>     #include <vtkPolyData.h>
>     #include <vtkPolyDataWriter.h>
>      
>     int main()
>     {
>     	//创建几何数据，没有拓扑数据
>     	vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
>     	points->InsertNextPoint(1.0,0.0,0.0);
>     	points->InsertNextPoint(0.0,0.0,0.0);
>     	points->InsertNextPoint(0.0,1.0,0.0);
>      
>     	//把几何数据(拓扑数据为空)放入到某个数据集中
>     	vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();
>     	polydata->SetPoints(points);
>      
>     	//将polydata类型的数据写到一个vtk文件中
>     	vtkSmartPointer<vtkPolyDataWriter> writer = vtkSmartPointer<vtkPolyDataWriter>::New();
>     	writer->SetFileName("PolyData.vtk");
>     	writer->SetInputData(polydata);
>     	writer->Write();
>      
>     	return 0;
>     }
> 
> 利用Notepad++打开文件；，利用ParaView可视化如下：
> 
> ![20170112232310265][]              ![20170112232315203][]

# 2. 零维拓扑结构——顶点 #

>     #include <vtkAutoInit.h>  
>     VTK_MODULE_INIT(vtkRenderingOpenGL); 
>      
>     #include <vtkSmartPointer.h>
>     #include <vtkPoints.h>    //几何结构
>     #include <vtkPolyData.h>  //数据集
>     #include <vtkPolyDataWriter.h>
>     #include <vtkCellArray.h> //拓扑结构
>      
>     int main()
>     {
>     	//创建点坐标
>     	int X[3] = {1.0,0.0,0.0};
>     	int Y[3] = {0.0,0.0,0.0};
>     	int Z[3] = {0.0,1.0,0.0};
>      
>     	//创建点数据&创建使每一个点加入类似顶点类型的Cell
>     	vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
>     	vtkSmartPointer<vtkCellArray> vertics = vtkSmartPointer<vtkCellArray>::New();
>     	for (unsigned int i=0; i<3; i++)
>     	{
>     		//定义用来存储点索引的中间变量，vtkIdType相当int long等类型
>     		vtkIdType pId[1];
>     		//把点坐标加入VTKPoints中，InserNextPoint()返回加入点的索引；
>     		//使用这个索引号创建定点类型Cell
>     		pId[0] = points->InsertNextPoint(X[i],Y[i],Z[i]);
>     		
>     		//每个坐标点都需要创建一个顶点Cell
>     		vertics->InsertNextCell(1,pId);
>     	}
>     	//创建VTKPolyData对象
>     	vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();
>     	//将几何结构 & 拓扑结构加入到数据集中
>     	polydata->SetPoints(points);
>     	polydata->SetVerts(vertics);
>     	//写数据、
>     	vtkSmartPointer<vtkPolyDataWriter> writer = vtkSmartPointer<vtkPolyDataWriter>::New();
>     	writer->SetFileName("TopoGeometry.vtk");
>     	writer->SetInputData(polydata);
>     	writer->Write();
>     
>      	return 0;
>     }
> 
>  
> 
> 与实验一不同之处在于该程序实例化了一个vtkCellArray的对象，前文说“点数据(Point Data)定义数据集的几何结构，单元数据(Cell Data)定义数据集的拓扑结构”。所以，vtkCellArray类型的对象vertices就是用来指定数据集polydata的拓扑结构，而polydata的几何结构则是由points来定义的。  
> 此处定义的数据集的拓扑结构是零维的点，即单元类型是Vertex（顶点）。
> 
> 利用Notepad++打开文件，利用ParaView可视化如下：
> 
>  
> 
> ![20170112232813758][]         ![20170112232820164][]

#  3. 一维拓扑结构及实验 #

>  
> 
>     #include <vtkAutoInit.h>  
>     VTK_MODULE_INIT(vtkRenderingOpenGL); 
>      
>     #include <vtkSmartPointer.h>
>     #include <vtkPoints.h>
>     #include <vtkCellArray.h>
>     #include <vtkPolyData.h>
>     #include <vtkPolyDataWriter.h>
>     #include <vtkLine.h> //构建两个端点的连线
>     int main()
>     {
>     	//创建三个点坐标
>     	vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
>     	points->InsertNextPoint(1.0,0.0,0.0); // ID=0;
>     	points->InsertNextPoint(0.0,0.0,0.0); // ID=1;
>     	points->InsertNextPoint(0.0,1.0,0.0); // ID=2;
>     	//每两个点之间用直线连接
>     	//SetId（para1，para2）;para1:出发端点的ID；para2：连接端点的ID
>     	vtkSmartPointer<vtkLine> line0 = vtkSmartPointer<vtkLine>::New();
>     	line0->GetPointIds()->SetId(0,0);
>     	line0->GetPointIds()->SetId(1,1);
>      
>     	vtkSmartPointer<vtkLine> line1 = vtkSmartPointer<vtkLine>::New();
>     	line1->GetPointIds()->SetId(0,1);
>     	line1->GetPointIds()->SetId(1,2);
>      
>     	vtkSmartPointer<vtkLine> line2 = vtkSmartPointer<vtkLine>::New();
>     	line2->GetPointIds()->SetId(0,2);
>     	line2->GetPointIds()->SetId(1,0);
>     	//创建Cell，存储拓扑特征：线段
>     	vtkSmartPointer<vtkCellArray> LineCell = vtkSmartPointer<vtkCellArray>::New();
>     	LineCell->InsertNextCell(line0);
>     	LineCell->InsertNextCell(line1);
>     	LineCell->InsertNextCell(line2);
>     	
>     	//创建数据集，并转入拓扑结构和几何结构
>     	vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();
>     	polydata->SetPoints(points);
>     	polydata->SetLines(LineCell);
>      
>     	//写数据
>     	vtkSmartPointer<vtkPolyDataWriter> writer = vtkSmartPointer<vtkPolyDataWriter>::New();
>     	writer->SetFileName("DataStruct2D");
>     	writer->SetInputData(polydata);
>     	writer->Write();
>      
>     	return 0;
>     }
> 
> 利用Notepad++打开文件，利用ParaView可视化如下：
> 
> ![20170112233631261][]   ![20170112233637168][]

> # 4. 总结 #
> 
>   
> 对于VTK的数据集而言，数据集的几何结构和拓扑结构是其必不可少的两个部分。实验一只定义了数据集的几何结构，没有定义该数据集的拓扑结构，所以该数据集不能直接显示；实验二和实验三除了定义数据集的几何结构(由points定义)，还定义了相应的拓扑结构。其中实验二定义的是零维的点拓扑结构；实验三定义的是一维的线拓扑结构，它们都是保存在由类vtkCellArray所实例化的对象里，除了零维的点、一维的线等类型的单元以外，VTK还定义了其他类型的单元。  
>

[20170112232310265]: https://img-blog.csdn.net/20170112232310265
[20170112232315203]: https://img-blog.csdn.net/20170112232315203
[20170112232813758]: https://img-blog.csdn.net/20170112232813758
[20170112232820164]: https://img-blog.csdn.net/20170112232820164
[20170112233631261]: https://img-blog.csdn.net/20170112233631261
[20170112233637168]: https://img-blog.csdn.net/20170112233637168