构建vtkUnstructuredGrid对象

为了读取不同格式的有限元计算结果文件，我们先写一个FEDataModel类来管理有限元的几何拓扑和属性信息。

class FEDataModel:"""有限元数据模型类"""def __init__(self):self.nodes = []  # 节点几何坐标self.elements = []  # 单元拓扑信息self.scalars = {}  # 节点标量属性self.vectors = {}  # 节点向量属性self.ugrid = vtk.vtkUnstructuredGrid()  # 用于VTK可视化的数据模型self.ugrid.Allocate(100)def read_inp(self, filename):with open(filename) as f:node_flag, element_flag = False, Falsefor line in f.readlines():line = line.replace('\n', '').replace(' ', '')if '*ELEMENT' in line:node_flag, element_flag = False, Truecontinueelif '*NODE' in line:node_flag, element_flag = True, Falsecontinueelif '*' in line:node_flag, element_flag = False, Falsecontinueif node_flag:self.nodes.append(list(map(lambda x: float(x), line.split(',')))[1:])elif element_flag:self.elements.append(list(map(lambda x: int(x) - 1, line.split(',')))[1:])# print(len(self.nodes), len(self.elements))nodes = vtk.vtkPoints()for i in range(0, len(self.nodes)):nodes.InsertPoint(i, self.nodes[i])for i in range(0, len(self.elements)):if len(self.elements[i]) == 4:  # 四面体单元self.ugrid.InsertNextCell(vtk.VTK_TETRA, 4, self.elements[i])elif len(self.elements[i]) == 6:  # 六面体单元self.ugrid.InsertNextCell(vtk.VTK_POLYGON, 6, self.elements[i])elif len(self.elements[i]) == 3:  # 三角面片单元self.ugrid.InsertNextCell(vtk.VTK_TRIANGLE, 3, self.elements[i])else:print("FEDataModel构建中遇到错误单元类型！")self.ugrid.SetPoints(nodes)def read_ntl(self, filename):with open(filename) as f:lines = f.readlines()attribute_name = ''.join(lines[0].split(' ')[1:-1])scalar = []for line in lines[4:]:line = line.replace('\n', '').split(' ')scalar.append(float(line[-1]))self.scalars[attribute_name] = scalar# print(attribute_name + ' scalar number: ' + str(len(scalar)))# 存储标量值scalars = vtk.vtkFloatArray()scalars.SetName(attribute_name)for i in range(0, len(scalar)):scalars.InsertTuple1(i, scalar[i])# 设定每个节点的标量值self.ugrid.GetPointData().SetScalars(scalars)def display(self):renderer = vtk.vtkRenderer()renWin = vtk.vtkRenderWindow()renWin.AddRenderer(renderer)iren = vtk.vtkRenderWindowInteractor()iren.SetRenderWindow(renWin)colors = vtk.vtkNamedColors()ugridMapper = vtk.vtkDataSetMapper()ugridMapper.SetInputData(self.ugrid)ugridActor = vtk.vtkActor()ugridActor.SetMapper(ugridMapper)ugridActor.GetProperty().SetColor(colors.GetColor3d("Peacock"))ugridActor.GetProperty().EdgeVisibilityOn()renderer.AddActor(ugridActor)renderer.SetBackground(colors.GetColor3d("Beige"))renderer.ResetCamera()renderer.GetActiveCamera().Elevation(60.0)renderer.GetActiveCamera().Azimuth(30.0)renderer.GetActiveCamera().Dolly(1.2)renWin.SetSize(640, 480)# Interact with the data.renWin.Render()iren.Start()

这个类的作用是，方便我们读取并构建用于在VTK中显示的vtkUnstructuredGrid类对象。vtkUnstructuredGrid类是VTK中的非结构化网格类，可用于有限元分析、计算几何和几何建模这类领域。

vtkUnstructuredGrid类详情参见：VTK笔记-使用vtkUnstructuredGrid类构建非结构化数据。

其中read_inp成员函数和read_ntl成员函数分别用于读取从ProCAST软件中导出的inp文件（存储有限元的几何拓扑数据）和ntl文件（存储有限元的节点属性数据，如温度、应力等）。

存储vtkUnstructuredGrid对象

为了能一次性读取有限元模型整体数据，我们可以将其保存为vtk格式的文件。

writer = vtk.vtkUnstructuredGridWriter()
writer.SetFileName(save_fn)
writer.SetInputData(self.FEModel.ugrid)
writer.Write()
writer.Update()

下一次只需读取对应的vtk文件即可。

reader = vtk.vtkUnstructuredGridReader()
reader.SetFileName(read_fn)
reader.Update()
self.FEModel.ugrid = reader.GetOutput()

云图可视化

可视化节点属性数据（标量场），关键代码如下：

def drawScalarField(self, scalar_mapper, scalarRange, title):# 定义颜色映射表lut = vtk.vtkLookupTable()lut.SetHueRange(0.67, 0.0)  # 色调范围从红色到蓝色# lut.SetAlphaRange(1.0, 1.0) # 透明度范围# lut.SetValueRange(1.0, 1.0)# lut.SetSaturationRange(1.0, 1.0) # 颜色饱和度# lut.SetNumberOfTableValues(256)lut.SetNumberOfColors(256)  # 颜色个数# lut.SetRange(scalarRange)lut.Build()scalar_mapper.SetScalarRange(scalarRange)scalar_mapper.SetLookupTable(lut)scalar_actor = vtk.vtkActor()scalar_actor.SetMapper(scalar_mapper)self.renderer.AddActor(scalar_actor)# 色标带scalarBar = vtk.vtkScalarBarActor()scalarBar.SetLookupTable(scalar_mapper.GetLookupTable())  # 将颜色查找表传入窗口中的色标带scalarBar.SetTitle(title)scalarBar.SetNumberOfLabels(5)self.renderer.AddActor2D(scalarBar)

结果展示