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。

 1 import vtk
 2 
 3 # 自定义动作
 4 class MyInteractor(vtk.vtkInteractorStyleTrackballCamera):
 5     def __init__(self, parent=None):
 6         self.AddObserver("RightButtonPressEvent", self.RightButtonPressEvent)
 7 
 8     def SetVisibleFilter(self, vis):
 9         self.VisibleFilter = vis
10 
11     def RightButtonPressEvent(self, obj, event):
12         self.VisibleFilter.Update()
13 
14         print("number of visible points: ", self.VisibleFilter.GetOutput().GetNumberOfPoints())
15 
16         mapper = vtk.vtkPolyDataMapper()
17         mapper.SetInputData(self.VisibleFilter.GetOutput())
18         actor = vtk.vtkActor()
19         actor.SetMapper(mapper)
20         actor.GetProperty().SetPointSize(2)
21         actor.GetProperty().SetColor(1, 0, 0)
22         self.GetDefaultRenderer().AddActor(actor)
23 
24         self.OnRightButtonDown()
25         return
26 
27 
28 def CreateScene(mesh):
29     renWin = vtk.vtkRenderWindow()
30     ren = vtk.vtkRenderer()
31 
32     # 设置背景颜色
33     ren.GradientBackgroundOn()
34     ren.SetBackground(0.1, 0.1, 0.1)
35     ren.SetBackground2(0.8, 0.8, 0.8)
36 
37     # 设置窗口大小
38     renWin.SetSize(600, 600)
39     renWin.AddRenderer(ren)
40 
41     iren = vtk.vtkRenderWindowInteractor()
42     iren.SetRenderWindow(renWin)
43 
44     # 添加自定义动作
45     style = MyInteractor()
46     style.SetDefaultRenderer(ren)
47     iren.SetInteractorStyle(style)
48 
49     mapper = vtk.vtkPolyDataMapper()
50     mapper.SetInputData(mesh)
51     actor = vtk.vtkLODActor()
52     actor.SetMapper(mapper)
53     ren.AddActor(actor)
54 
55     visPts = vtk.vtkSelectVisiblePoints()
56     visPts.SetInputData(mesh)
57     visPts.SetRenderer(ren)
58     style.SetVisibleFilter(visPts)
59 
60     renWin.Render()
61     iren.Initialize()
62     iren.Start()
63 
64 
65 if __name__ == "__main__":
66     filename = "xxxx.obj"
67     reader = vtk.vtkOBJReader()
68     reader.SetFileName(filename)
69     reader.Update()
70     mesh = reader.GetOutput()
71     CreateScene(mesh)