add vtk notes

_posts/2023-06-22-show-hdf5-data-using-vtkUnstructuredGrid.md

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+---
+title: vtkUnstructuredGrid 显示 HDF5 数据
+date: 2023-06-22 +0800 # 2022-01-01 13:14:15 +0800 只写日期也行；不写秒也行；这样也行 2022-03-09T00:55:42+08:00
+categories: [VTK]
+tags: [VTK]      # TAG names should always be lowercase
+
+# 以下默认false
+math: true
+mermaid: true
+# pin: true
+---
+
+# vtkUnstructuredGrid 显示 HDF5 数据
+
+## Reference
+
+* [VTK examples](https://github.com/Kitware/vtk-examples/blob/c1c8af1e70708e65d6fa4bf69fab814f03c99dc2/src/Cxx/GeometricObjects/Hexahedron.cxx)
+
+## 添加 field (dataset) 数据
+
+### 第一步，创建VTK的`field`数据
+
+```C++
+vtkSmartPointer<vtkDoubleArray> fieldDataArray = vtkSmartPointer<vtkDoubleArray>::New();
+fieldDataArray->SetNumberOfComponents(1); // assuming scalar data
+
+// Assuming "dataset" is your std::map<std::string, std::vector<double>>
+for (const auto& pair : dataset) {
+    const std::string& fieldName = pair.first;
+    const std::vector<double>& fieldValues = pair.second;
+
+    fieldDataArray->SetName(fieldName.c_str());
+    for (double value : fieldValues) {
+        fieldDataArray->InsertNextValue(value);
+    }
+
+    // Assuming "grid" is your vtkUnstructuredGrid object
+    grid->GetPointData()->AddArray(fieldDataArray);
+}
+```
+
+* 根据`dataset`的属性`field`是`scalar`数据还是`tensor`数据，设置`SetNumberOfComponents`的参数；
+* 根据`dataset`的属性`field`是`scalar`数据还是`tensor`数据，选择`InsertNectValue`或者`InsertNextTuple`；
+* 根据`dataset`的属性`location type`属性是`vetex`还是`element`，`grid`选取`GetPointData`或者`GetCellData`；
+
+### 第二步，添加VTK `field`数据到`mapper`
+
+```C++
+vtkSmartPointer<vtkDataSetMapper> mapper = vtkSmartPointer<vtkDataSetMapper>::New();
+mapper->SetInputData(grid);
+mapper->SetScalarModeToUsePointData(); // or SetScalarModeToUseCellData()
+mapper->SelectColorArray("fieldName"); // replace "fieldName" with the name of the field you want to use for coloring
+
+vtkSmartPointer<vtkLookupTable> lut = vtkSmartPointer<vtkLookupTable>::New();
+lut->SetRange(minValue, maxValue); // set range according to your data
+mapper->SetLookupTable(lut);
+
+vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
+actor->SetMapper(mapper);
+
+vtkSmartPointer<vtkScalarBarActor> scalarBar = vtkSmartPointer<vtkScalarBarActor>::New();
+scalarBar->SetLookupTable(mapper->GetLookupTable());
+
+vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
+renderer->AddActor(actor);
+renderer->AddActor2D(scalarBar);
+```
+
+* 根据`dataset`的属性`location type`属性是`vetex`还是`element`，`mapper`调用`SetScalarModeToUsePointData`或者`SetScalarModeToUseCellData`；
+
+## 颜色转换的另一种方式
+
+使用`vtkColorTranslationFunction`转换：
+
+```C++
+// Create a vtkColorTransferFunction to map scalar values to colors
+vtkSmartPointer<vtkColorTransferFunction> colorTransferFunction = vtkSmartPointer<vtkColorTransferFunction>::New();
+colorTransferFunction->AddRGBPoint(minScalarValue, r, g, b); // Add as many points as needed
+
+// Set the color transfer function for the mapper
+mapper->SetLookupTable(colorTransferFunction);
+```

_posts/2023-07-02-VTK-official-examples.md

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+---
+title: VTK 官方examples记录，及优秀VTK blog列表
+date: 2023-05-24 +0800 # 2022-01-01 13:14:15 +0800 只写日期也行；不写秒也行；这样也行 2022-03-09T00:55:42+08:00
+categories: [VTK]
+tags: [VTK]      # TAG names should always be lowercase
+
+# 以下默认false
+math: true
+mermaid: true
+# pin: true
+---
+
+# VTK 官方examples记录，及优秀VTK blog列表
+
+## 概览列表
+
+关于CXX的示例说明，在官方examples代码的相关README里面有简单介绍，路径：src/Cxx.md
+
+* github `HDF5` & `TDR`代码 [JosefWeinbub](https://github.com/JosefWeinbub?tab=stars)
+* C++示例代码列表 [Cxx](https://examples.vtk.org/site/Cxx/)
+* 演示`vtkUnstructureGrid`及mesh显示(`EdgeVisibilityOn`) [UGrid](https://examples.vtk.org/site/Cxx/UnstructuredGrid/UGrid/)
+
+## Color a mesh by dotting a vector from the origin to each point with a specified vector
+* [SimpleElevationFilter](https://examples.vtk.org/site/Cxx/Meshes/SimpleElevationFilter/)
+
+## Vector field -- 显示矢量场箭头
+* [VectorField](https://examples.vtk.org/site/Cxx/Visualization/VectorField/)
+* [VectorFieldNonZeroExtraction](https://examples.vtk.org/site/Cxx/Filtering/VectorFieldNonZeroExtraction/)
+
+## VTK blog
+* [VTK入门范例2](https://www.michaelapp.com/posts/2019/2019-03-20-VTK%E5%85%A5%E9%97%A8%E8%8C%83%E4%BE%8B2/)

_posts/2023-07-09-vtk-notes.md

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+---
+title: VTK 笔记
+date: 2023-07-09 +0800 # 2022-01-01 13:14:15 +0800 只写日期也行；不写秒也行；这样也行 2022-03-09T00:55:42+08:00
+categories: [VTK]
+tags: [VTK]      # TAG names should always be lowercase
+
+# 以下默认false
+math: true
+mermaid: true
+# pin: true
+---
+
+# VTK 笔记
+
+## vtkUnstructuredGrid 添加数据
+
+* SetScalar、Vector = AddArray + SetActiveScalar\Vector 类似问题，看源码，不同的filter会取不同的activeAttribute，具体设置哪个active还是取决于filter
+* setActive 不是2选一的关系