vtk中实现裁剪

tt posted @ 2007年10月13日 04:38 in vtk , 9851 阅读

    在VTK中，我们通常需要的并不是严格标准的几何体，我们需要对这些几何体进行加工，修改其内容，得到我们想要的效果，下面结合例子介绍如何在VTK中实现对几何体的裁剪。

    要对几何体进行裁剪，需要建立好几何体模型，然后定义一个隐函数，利用vtkClipPolyData，通过隐函数vtkImplicitFunction实现对模型的裁剪，在vtk中，类似vtkPlane，vtkSphere，vtkCylinder这些后面没有Source的类，都是隐函数类。

    看下面这个例子（cut_sphere.cxx）： 

  1. #include "vtkActor.h"
  2. #include "vtkRenderer.h"
  3. #include "vtkRenderWindow.h"
  4. #include "vtkRenderWindowInteractor.h"
  5. #include "vtkCylinder.h"
  6. #include "vtkPlane.h"
  7. #include "vtkImplicitBoolean.h"
  8. #include "vtkPolyDataMapper.h"
  9. #include "vtkSphereSource.h"
  10. #include "vtkProperty.h"
  11. #include "vtkClipPolyData.h"
  12. #include "vtkTransformPolyDataFilter.h"
  13. #include "vtkTransform.h"
  14. #include "vtkInteractorStyleTrackballCamera.h"
  15.  
  16. int main()
  17. {
  18.     vtkSphereSource *sphere=vtkSphereSource::New();
  19.     sphere->SetCenter(0,0,0);
  20.     sphere->SetRadius(10);
  21.     sphere->SetThetaResolution(40);
  22.     sphere->SetPhiResolution(40);
  23.  
  24.     vtkCylinder *cylinder = vtkCylinder::New();//圆柱
  25.     cylinder->SetCenter(0,0,0);
  26.     cylinder->SetRadius(3);
  27.  
  28.     vtkPlane *vPlane = vtkPlane::New();//横截面
  29.     vPlane->SetOrigin(0, 0, 0);
  30.     vPlane->SetNormal(0, -1, 0);
  31.  
  32.     vtkImplicitBoolean *cuted_cylinder = vtkImplicitBoolean::New();
  33.     cuted_cylinder->SetOperationTypeToIntersection();
  34.     cuted_cylinder->AddFunction(cylinder);
  35.     cuted_cylinder->AddFunction(vPlane);
  36.  
  37.     vtkClipPolyData *clipper=vtkClipPolyData::New();
  38.     clipper->SetInputConnection(sphere->GetOutputPort());
  39.     clipper->SetClipFunction(cylinder);
  40.     clipper->GenerateClipScalarsOn();
  41.     clipper->GenerateClippedOutputOn();
  42.     clipper->SetValue(0.5);
  43.  
  44.     vtkTransform *transform=vtkTransform::New();
  45.     transform->Translate(7,0,0);
  46.     vtkTransformPolyDataFilter *filter=vtkTransformPolyDataFilter::New();
  47.     filter->SetInputConnection(clipper->GetOutputPort());
  48.     filter->SetTransform(transform);
  49.     vtkClipPolyData *clipper2=vtkClipPolyData::New();
  50.     clipper2->SetInputConnection(filter->GetOutputPort());
  51.     clipper2->SetClipFunction(cuted_cylinder);
  52.     clipper2->GenerateClipScalarsOn();
  53.     clipper2->GenerateClippedOutputOn();
  54.     clipper2->SetValue(0.5);
  55.  
  56.     vtkPolyDataMapper *map = vtkPolyDataMapper::New();
  57.     map->SetInputConnection(clipper2->GetOutputPort());
  58.     map->ScalarVisibilityOff();
  59.  
  60.     vtkActor *actor = vtkActor::New();
  61.     actor->SetMapper(map);
  62.     actor->GetProperty()->SetColor(0,1,1);
  63.     //actor->GetProperty()->SetAmbientColor(0.4,0.5,0.6);
  64.     //actor->GetProperty()->SetDiffuseColor(0.8,0.6,0.2);
  65.     actor->RotateX(40);
  66.  
  67.     vtkRenderer *ren = vtkRenderer::New();
  68.     vtkRenderWindow *renWin = vtkRenderWindow::New();
  69.     renWin->AddRenderer(ren);
  70.  
  71.     vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
  72.     iren->SetRenderWindow(renWin);
  73.  
  74.     ren->AddActor(actor);
  75.     ren->SetBackground(1, 1, 1);
  76.     renWin->SetSize(450, 450);
  77.  
  78.     vtkInteractorStyleTrackballCamera *style=vtkInteractorStyleTrackballCamera::New();
  79.     iren->SetInteractorStyle(style);
  80.  
  81.     iren->Initialize();
  82.     renWin->Render();
  83.    
  84.     iren->Start();
  85. }

 其中1～14行包含相应头文件

18～22行定义一个球，其圆心在原点，半径为10，设置经纬方向的三角片数均为40；

24～26行定义圆柱的隐函数，设定半径为3，中心在原点，在vtk中的圆柱隐函数是没有设定长度的，其方向为沿y轴方向，此处的圆柱用于对刚才定义的球进行裁剪，裁剪效果就是把球给打通了，两面都进行的裁剪，如果要只裁剪球的一面，则用半个圆柱。接下来的28～30行定义了一个平面，用平面与圆柱求交可得出半个圆柱。

32～35行将平面和圆柱进行Bool求交运算（SetOperationTypeToIntersection（））得出半个圆柱的隐函数表示cuted_cylinder，如果是求和运算则用SetOperationTypeToUnion（）。

37～42行定义了一个vtkClipPolyData对象clipper，将其输入设定为18～24行建立的球，裁剪函数设置为圆柱cylinder，接下来的三行40～42行似乎没有什么用处。

上面得到的只是用一个圆柱裁剪球的效果，但是为了同时显示用半个圆柱裁剪的效果，将刚才的裁剪体演x轴移动一定位置，然后用刚才Bool运算获得的半个圆柱进行裁剪，以便于比较。对几何对象的移动需要指定一个变换transform，然后定义一个vtkTransformPolyDataFilter对象filter，然后将filter的输入设定为要移动的几何对象，变换设定为transform。44～48行实现了将裁剪球的移动，其移动结果在filter中。

49～54行将移动后得到的filter作为新一次裁剪的输入，以半个圆柱cuted_cylinder为裁剪函数进行裁剪，得到裁剪结果clipper2

接下来的就是设定map，actor等常规对象了，在vtk不必细说了吧，

写好了程序代码， 接下来就是写CMakeLists.txt: 

  1. PROJECT (Main)
  2.  
  3. FIND_PACKAGE(VTK REQUIRED)
  4. IF(NOT VTK_USE_RENDERING)
  5.   MESSAGE(FATAL_ERROR "Example ${PROJECT_NAME} requires VTK_USE_RENDERING.")
  6. ENDIF(NOT VTK_USE_RENDERING)
  7. INCLUDE(${VTK_USE_FILE})
  8.  
  9. ADD_EXECUTABLE(main cut_cube.cxx)
  10. TARGET_LINK_LIBRARIES(main vtkRendering)

用cmake编译程序 

  1. $> cmake .
  2. $> make
  3.  

运行效果如下： 

         

旋转一下看其效果

 

 

 

 

 

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boardmodelpaper.com 说:
2024年1月19日 15:21

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