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【vtkWidgetRepresentation】第九期 vtk中的仿射变换

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前言

本文分享VTK中的仿射变换，实际结果如下图所示，希望对各位小伙伴有所帮助！

感谢各位小伙伴的点赞+关注，小易会继续努力分享，一起进步！

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1. vtkAffineRepresentation

        主要定义了仿射变换的几何表示。关键参数有：

1.1 GetTransform获取定义的线性变换矩阵。

1.2 SetTolerance，设置激活Handle的容差。

1.3 交互状态，包括：

Outside	外部
Rotate	旋转
Translate	移动
TranslateX	沿X轴移动
TranslateY	沿Y轴移动
ScaleWEdge	沿W边界缩放
ScaleEEdge	沿E边界缩放
ScaleNEdge	沿N边界缩放
ScaleSEdge	沿S边界缩放
ShearWEdge	沿W边界剪切
ShearEEdge	沿E边界剪切
ShearNEdge	沿N边界剪切
ShearSEdge	沿S边界剪切
MoveOriginX	中心点沿X轴移动
MoveOriginY	中心点沿Y轴移动
MoveOrigin	移动中心点

2. vtkAffineRepresentation2D

        vtkAffineRepresentation2D包含三部分：一个矩形，一个圆形和一个十字；矩形用于缩放和剪切；圆形用于旋转；十字用于移动。这三部分在视平面上进行显示，并保持一个恒定的高度和宽度。其重要参数如下：

2.1 设置不同部位的宽度

        SetBoxWidth，SetCircleWidth，SetAxesWidth

2.2 设置包围盒的原点

        SetOrigin

2.3 获取选中和未选中的属性

        Set/GetProperty，Set/GetSelectedProperty， Set/GetTextProperty

2.4 获取显示的文字

        SetDisplayText/GetDisplayText

3. vtkAffineWidget及其应用

#include <vtkActor.h>
#include <vtkAffineRepresentation2D.h>
#include <vtkAffineWidget.h>
#include <vtkAppendPolyData.h>
#include <vtkCommand.h>
#include <vtkInteractorStyleSwitch.h>
#include <vtkPlaneSource.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkTransform.h>

class vtkAffineCallback : public vtkCommand
{
public:
  static vtkAffineCallback *New()
    { return new vtkAffineCallback; }
  virtual void Execute(vtkObject *caller, unsigned long, void*);
  vtkAffineCallback():Actor(0),AffineRep(0)
  {
      this->Transform = vtkTransform::New();
  }
  ~vtkAffineCallback()
  {
      this->Transform->Delete();
  }
  vtkActor *Actor;
  vtkAffineRepresentation2D *AffineRep;
  vtkTransform *Transform;
};

void vtkAffineCallback::Execute(vtkObject*, unsigned long vtkNotUsed(event), void*)
{
  this->AffineRep->GetTransform(this->Transform);
  this->Actor->SetUserTransform(this->Transform);
}

int main(int, char *[])
{
  // Create two spheres: a larger one and a smaller one on top of the larger one
  // to show a reference point while rotating
  vtkSmartPointer<vtkSphereSource> sphereSource =
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->Update();

  vtkSmartPointer<vtkSphereSource> sphereSource2 =
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource2->SetRadius(0.075);
  sphereSource2->SetCenter(0,0.5,0);
  sphereSource2->Update();

  // Append the two spheres into one vtkPolyData
  vtkSmartPointer<vtkAppendPolyData> append =
    vtkSmartPointer<vtkAppendPolyData>::New();
  append->AddInputConnection(sphereSource->GetOutputPort());
  append->AddInputConnection(sphereSource2->GetOutputPort());

  // Create a plane centered over the larger sphere with 4x4 sub sections
  vtkSmartPointer<vtkPlaneSource> planeSource =
    vtkSmartPointer<vtkPlaneSource>::New();
  planeSource->SetXResolution(4);
  planeSource->SetYResolution(4);
  planeSource->SetOrigin(-1,-1,0);
  planeSource->SetPoint1(1,-1,0);
  planeSource->SetPoint2(-1,1,0);

  // Create a mapper and actor for the plane: show it as a wireframe
  vtkSmartPointer<vtkPolyDataMapper> planeMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  planeMapper->SetInputConnection(planeSource->GetOutputPort());
  vtkSmartPointer<vtkActor> planeActor =
    vtkSmartPointer<vtkActor>::New();
  planeActor->SetMapper(planeMapper);
  planeActor->GetProperty()->SetRepresentationToWireframe();
  planeActor->GetProperty()->SetColor(1,0,0);

  // Create a mapper and actor for the spheres
  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(append->GetOutputPort());
  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  // Create a renderer and render window
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  renderer->AddActor(actor);
  renderer->AddActor(planeActor);
  renderer->GradientBackgroundOn();
  renderer->SetBackground(1,1,1);
  renderer->SetBackground2(0,0,1);

  // Create an interactor
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);
  dynamic_cast<vtkInteractorStyleSwitch*>(
    renderWindowInteractor->GetInteractorStyle())->SetCurrentStyleToTrackballCamera();

  // Create an affine widget to manipulate the actor
  // the widget currently only has a 2D representation and therefore applies transforms in the X-Y plane only
  vtkSmartPointer<vtkAffineWidget> affineWidget =
    vtkSmartPointer<vtkAffineWidget>::New();
  affineWidget->SetInteractor(renderWindowInteractor);
  affineWidget->CreateDefaultRepresentation();
  dynamic_cast<vtkAffineRepresentation2D*>(affineWidget->GetRepresentation())->PlaceWidget(actor->GetBounds());

  vtkSmartPointer<vtkAffineCallback> affineCallback =
      vtkSmartPointer<vtkAffineCallback>::New();
  affineCallback->Actor = actor;
  affineCallback->AffineRep = dynamic_cast<vtkAffineRepresentation2D*>(affineWidget->GetRepresentation());

  affineWidget->AddObserver(vtkCommand::InteractionEvent,affineCallback);
  affineWidget->AddObserver(vtkCommand::EndInteractionEvent,affineCallback);

  renderWindow->Render();
  renderWindowInteractor->Initialize();
  renderWindow->Render();
  affineWidget->On();

  // begin mouse interaction
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

结论：

感谢各位小伙伴的点赞+关注，小易会继续努力分享，一起进步！

你的赞赏是我的最最最最大的动力(＾Ｕ＾)ノ~ＹＯ