VTK框选拾取三角面片
最近需要实现拾取三角面片的交互功能,看了官方示例和网友分享,都是使用vtkInteractorStyleRubberBandPick搭配vtkAreaPicker。但是具体实现方法都是选择继承vtkInteractorStyleRubberBandPick的方式,重写里面的方法。我觉得使用观察者命令模式去实现这个功能是更合理便捷的方法。
效果预览
功能说明
通过鼠标框选模型表面的面片,然后利用红色边框显示被框选的三角面片
方法介绍
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利用vtkInteractorStyleRubberBandPick交互方式实现框选。(通过R键切换交互模式和框选模式)
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利用vtkAreaPicker收集框选的信息。VTK还提供了vtkCellPicker,但是CellPicker只能选中某个对象,不能框选一个集合。
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利用观察者命令模式来实现显示被框选面片的逻辑功能。
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源代码中已经写好详细注释。
源代码
完整代码可以直接编译运行
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkInteractorStyleRubberBandPick.h>
#include <vtkAreaPicker.h>
#include <vtkCommand.h>
#include <vtkCallbackCommand.h>
#include <vtkExtractPolyDataGeometry.h>
#include <vtkSphereSource.h>
#include <vtkPlanes.h>
#include <vtkDataSetMapper.h>
#include <vtkProperty.h>
class vtkPickerCallback : public vtkCommand
{
public:
static vtkPickerCallback* New() {return new vtkPickerCallback;}
virtual void Execute(vtkObject* caller, unsigned long, void*);
void SetPolyData(vtkPolyData* input);
void SetRenderer(vtkRenderer* input);
private:
vtkPolyData* polyData;
vtkRenderer* renderer;
vtkDataSetMapper* mapper;
vtkActor* actor;
};
int main()
{
vtkSphereSource* sphere = vtkSphereSource::New();
sphere->SetThetaResolution(18);
sphere->SetPhiResolution(18);
sphere->SetRadius(10);
sphere->SetCenter(0, 0, 0);
sphere->Update();
vtkPolyDataMapper* mapper = vtkPolyDataMapper::New();
mapper->SetInputConnection(sphere->GetOutputPort());
vtkActor* actor = vtkActor::New();
actor->SetMapper(mapper);
vtkRenderer* renderer = vtkRenderer::New();
renderer->AddActor(actor);
vtkRenderWindow* renderWindow = vtkRenderWindow::New();
renderWindow->AddRenderer(renderer);
vtkRenderWindowInteractor* renderWindowInteractor = vtkRenderWindowInteractor::New();
vtkInteractorStyleRubberBandPick* interactorStyle = vtkInteractorStyleRubberBandPick::New();
vtkPickerCallback* callback = vtkPickerCallback::New();
callback->SetPolyData(sphere->GetOutput());
callback->SetRenderer(renderer);
vtkAreaPicker* areaPicker = vtkAreaPicker::New();
areaPicker->AddObserver(vtkCommand::EndPickEvent, callback);
renderWindowInteractor->SetRenderWindow(renderWindow);
renderWindowInteractor->SetInteractorStyle(interactorStyle);
renderWindowInteractor->SetPicker(areaPicker);
renderWindowInteractor->Start();
return 0;
}
void vtkPickerCallback::Execute(vtkObject* caller, unsigned long, void*)
{
vtkAreaPicker* areaPicker = static_cast<vtkAreaPicker*>(caller);
vtkPlanes* frustum = areaPicker->GetFrustum();
vtkExtractPolyDataGeometry* extract = vtkExtractPolyDataGeometry::New();
extract->SetInputData(polyData);
extract->SetImplicitFunction(frustum);
extract->Update();
mapper->SetInputConnection(extract->GetOutputPort());
mapper->ScalarVisibilityOff();
actor->GetProperty()->SetColor(1, 0, 0);
actor->GetProperty()->SetPointSize(5);
actor->GetProperty()->SetRepresentationToWireframe();
renderer->AddActor(actor);
}
void vtkPickerCallback::SetPolyData(vtkPolyData* input)
{
polyData = input;
}
void vtkPickerCallback::SetRenderer(vtkRenderer* input)
{
renderer = input;
mapper = vtkDataSetMapper::New();
actor = vtkActor::New();
actor->SetMapper(mapper);
}
存在问题
因为算法上是利用框选后生成的视锥体去切割模型然后提取视锥体内的面片,所以会出现将前面和后面的面片都被囊括进来。我在下一篇文章会解决这个问题。 下一篇:VTK框选表面拾取面片——仅选中前表面
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