vtk-py z-Buffer可见算法

C++版例子：

https://lorensen.github.io/VTKExamples/site/Cxx/PolyData/SelectVisiblePoints/

优点：

• Simple to use
• Can be implemented easily in object or image sapce
• Can be executed quickly, even with many polygons

缺点

• Takes up a lot of memory
• Can't do transparent surfaces without additional code

示例用法：

自定义输入资源，左键旋转，右键显示当前可见点。

 import vtk

 # 自定义动作
 class MyInteractor(vtk.vtkInteractorStyleTrackballCamera):
     def __init__(self, parent=None):
         self.AddObserver("RightButtonPressEvent", self.RightButtonPressEvent)

     def SetVisibleFilter(self, vis):
         self.VisibleFilter = vis

     def RightButtonPressEvent(self, obj, event):
         self.VisibleFilter.Update()

         print("number of visible points: ", self.VisibleFilter.GetOutput().GetNumberOfPoints())

         mapper = vtk.vtkPolyDataMapper()
         mapper.SetInputData(self.VisibleFilter.GetOutput())
         actor = vtk.vtkActor()
         actor.SetMapper(mapper)
         actor.GetProperty().SetPointSize(2)
         actor.GetProperty().SetColor(1, 0, 0)
         self.GetDefaultRenderer().AddActor(actor)

         self.OnRightButtonDown()
         return

 def CreateScene(mesh):
     renWin = vtk.vtkRenderWindow()
     ren = vtk.vtkRenderer()

     # 设置背景颜色
     ren.GradientBackgroundOn()
     ren.SetBackground(0.1, 0.1, 0.1)
     ren.SetBackground2(0.8, 0.8, 0.8)

     # 设置窗口大小
     renWin.SetSize(600, 600)
     renWin.AddRenderer(ren)

     iren = vtk.vtkRenderWindowInteractor()
     iren.SetRenderWindow(renWin)

     # 添加自定义动作
     style = MyInteractor()
     style.SetDefaultRenderer(ren)
     iren.SetInteractorStyle(style)

     mapper = vtk.vtkPolyDataMapper()
     mapper.SetInputData(mesh)
     actor = vtk.vtkLODActor()
     actor.SetMapper(mapper)
     ren.AddActor(actor)

     visPts = vtk.vtkSelectVisiblePoints()
     visPts.SetInputData(mesh)
     visPts.SetRenderer(ren)
     style.SetVisibleFilter(visPts)

     renWin.Render()
     iren.Initialize()
     iren.Start()

 if __name__ == "__main__":
     filename = "xxxx.obj"
     reader = vtk.vtkOBJReader()
     reader.SetFileName(filename)
     reader.Update()
     mesh = reader.GetOutput()
     CreateScene(mesh)