如何告訴VTK管道使用通過TimerEvent更新的新vtkPolyData？

Question

意向

我寫了一個VTK應用程序，使用vtkPoints> vtkPolyLine> vtkPolyData> vtkPolyDataMapper生成螺旋並顯示它。 如果在程序初始化時靜態完成，這可以正常工作。 現在，我想動態添加新的數據點。 目的是實時顯示測量結果，因此將以特定間隔添加新數據。

問題

目前，我剛剛實現了一個TimerEvent來更新vtkPoints和vtkPolyLine。 但是，程序只顯示在vtkRenderWindowInteractor啟動之前生成的靜態數據。 我還嘗試使用“Modified（）”和“Update（）”調用幾乎所有對象，嘗試刪除，重新生成並向渲染器添加新actor - 但沒有成功！ 我在下面添加了我的C ++代碼......

關聯問題

以下郵件列表問題是關於這個問題，但給出的解決方案對我不起作用： http ：//public.kitware.com/pipermail/vtkusers/2006-November/038377.html

以下問題似乎是相關的，但沒有有用的答案： VTK：在每個模擬時間步驟更新renderWindow中的數據點

問題

1. 如何告訴VTK vtkPolyData對象已更改？
2. 我應該仔細研究一下VTK用戶指南？

詳細信息/源代碼

我正在使用Visual Studio Community 2017和VTK 8.0.0，它們都編譯為Win32目標。

#include <vtkAutoInit.h>
VTK_MODULE_INIT(vtkRenderingOpenGL2);
VTK_MODULE_INIT(vtkRenderingContextOpenGL2);
VTK_MODULE_INIT(vtkRenderingVolumeOpenGL2);
VTK_MODULE_INIT(vtkInteractionStyle);
VTK_MODULE_INIT(vtkRenderingFreeType);

#include <vtkSmartPointer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkConeSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkProperty.h>

#include <vtkPoints.h>
#include <vtkPolyLine.h>


vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
vtkSmartPointer<vtkPolyLine> polyLine = vtkSmartPointer<vtkPolyLine>::New();

int numOfPoints = 0;
double t = 0;

void NextPoint() {
    double x = t * cos(t);
    double y = t * sin(t);
    points->InsertNextPoint(x, y, t);
    polyLine->GetPointIds()->InsertNextId(numOfPoints);

    numOfPoints++;
    t += 0.1;
}

vtkSmartPointer<vtkPolyData> generateEllipse() {
    // Add some points so we actually see something at all...
    for (int i = 0; i < 100; ++i) {
        NextPoint();
    }

    vtkSmartPointer<vtkCellArray> cells = vtkSmartPointer<vtkCellArray>::New();
    cells->InsertNextCell(polyLine);

    vtkSmartPointer<vtkPolyData> polyData = vtkSmartPointer<vtkPolyData>::New();
    polyData->SetPoints(points);
    polyData->SetLines(cells);

    return polyData;
}


class vtkTimerCallback : public vtkCommand
{
public:
    static vtkTimerCallback *New()
    {
        vtkTimerCallback *cb = new vtkTimerCallback;
        cb->TimerCount = 0;
        return cb;
    }

    virtual void Execute(vtkObject *vtkNotUsed(caller), unsigned long eventId,
        void *vtkNotUsed(callData))
    {
        if (vtkCommand::TimerEvent == eventId)
        {
            NextPoint(); // Add another point to polyData

            ++this->TimerCount;
            cout << this->TimerCount << endl;
        }

    }

private:
    int TimerCount;

};



int main(int argc, char** argv) {
    vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();

    vtkSmartPointer<vtkRenderWindowInteractor> rwi = vtkSmartPointer<vtkRenderWindowInteractor>::New();
    rwi->SetRenderWindow(renderWindow);

    vtkSmartPointer<vtkPolyData> data = generateEllipse();

    vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    mapper->SetInputData(data);

    vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
    actor->SetMapper(mapper);
    actor->GetProperty()->SetDiffuseColor(255, 255, 0);

    vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
    renderWindow->AddRenderer(renderer);
    renderer->AddActor(actor);
    renderer->ResetCamera();

    renderWindow->Render();

    // Add Timer Event...
    rwi->Initialize();
    vtkSmartPointer<vtkTimerCallback> cb = vtkSmartPointer<vtkTimerCallback>::New();
    rwi->AddObserver(vtkCommand::TimerEvent, cb);
    int timerId = rwi->CreateRepeatingTimer(100); // every 100ms
    std::cout << "timerId: " << timerId << std::endl;

    // Start Displaying...
    rwi->Start();

    return 0;
}

Answer 1

問題是當你調用cells->InsertNextCell(polyLine);時，指針不存儲cells->InsertNextCell(polyLine); 數據被復制，而不是指向，以便在數組中創建單元格的有效存儲（整個實現實際上是在vtkCellArray的標題中，因此您可以檢查它）。 因此，當您更新polyLine時，它對polydata沒有影響，因為polydata有自己的副本，您沒有更新。 以下代碼適用於我（您必須公開polydata和cellArray）：

virtual void Execute(vtkObject *vtkNotUsed(caller), unsigned long eventId,
    void *vtkNotUsed(callData))
{
    if (vtkCommand::TimerEvent == eventId)
    {
        NextPoint(); // Add another point to polyData

        cells->Initialize(); // reset the cells to remove the old spiral
        cells->InsertNextCell(polyLine); // re-insert the updated spiral
        cells->Modified(); // required to update
        data->Modified(); // required to update
        ++this->TimerCount;
        cout << polyLine->GetNumberOfPoints() << endl;
        renderWindow->Render(); // refresh the render window after each update
    }
}

Answer 2

昨天我使用vtkProgrammableDataObjectSource作為DataSource制定了另一種解決方案。 Tomj的解決方案是更直接和簡單的解決方案......但是，vtk.org上沒有C ++示例代碼，它解釋了如何使用vtkProgrammableDataObjectSource，我必須通過反復試驗來解決它。 所以我會在這里發布，因為它可能對其他人有所幫助：

#include <vtkAutoInit.h>
VTK_MODULE_INIT(vtkRenderingOpenGL2);
VTK_MODULE_INIT(vtkRenderingContextOpenGL2);
VTK_MODULE_INIT(vtkRenderingVolumeOpenGL2);
VTK_MODULE_INIT(vtkInteractionStyle);
VTK_MODULE_INIT(vtkRenderingFreeType);

#include <vtkSmartPointer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkConeSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkProperty.h>
#include <vtkPoints.h>
#include <vtkPolyLine.h>
#include <vtkProgrammableFilter.h>
#include <vtkCallbackCommand.h>
#include <vtkPolyDataStreamer.h>

#include <vtkProgrammableDataObjectSource.h>


vtkSmartPointer<vtkProgrammableDataObjectSource> pDOS = vtkSmartPointer<vtkProgrammableDataObjectSource>::New();
vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();

vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
vtkSmartPointer<vtkPolyLine> polyLine = vtkSmartPointer<vtkPolyLine>::New();

int numOfPoints = 0;
double t = 0;

void NextPoint() {
    double x = t * cos(t);
    double y = t * sin(t);
    points->InsertNextPoint(x, y, t);
    polyLine->GetPointIds()->InsertNextId(numOfPoints);

    numOfPoints++;
    t += 0.1;
}

void generateEllipse(void *caller) {
    vtkProgrammableDataObjectSource *pDOS = vtkProgrammableDataObjectSource::SafeDownCast((vtkObjectBase*)caller);

    vtkSmartPointer<vtkCellArray> cells = vtkSmartPointer<vtkCellArray>::New();
    cells->InsertNextCell(polyLine);

    vtkSmartPointer<vtkPolyData> polyData = vtkSmartPointer<vtkPolyData>::New();
    polyData->SetPoints(points);
    polyData->SetLines(cells);

    pDOS->SetOutput(polyData);
}


int counter2 = 0;
void TimerCallbackFunction(vtkObject* caller, long unsigned int vtkNotUsed(eventId), void* clientData, void* vtkNotUsed(callData)) {
    cout << "timer callback: " << counter2 << endl;

// To avoid globals we can implement this later... 
//  vtkSmartPointer<vtkProgrammableDataObjectSource> pDOS =
//      static_cast<vtkProgrammableDataObjectSource*>(clientData);

    vtkRenderWindowInteractor *rwi =
        static_cast<vtkRenderWindowInteractor*>(caller);

    NextPoint();

    pDOS->Modified();
    rwi->Render();
    renderer->ResetCamera(); // Optional: Reposition Camera, so it displays the whole object

    counter2++;
}



int main(int argc, char** argv) {
    vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();

    vtkSmartPointer<vtkRenderWindowInteractor> rwi = vtkSmartPointer<vtkRenderWindowInteractor>::New();
    rwi->SetRenderWindow(renderWindow);


    pDOS->SetExecuteMethod(&generateEllipse, pDOS);

    vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    mapper->SetInputConnection(pDOS->GetOutputPort());

    vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
    actor->SetMapper(mapper);
    actor->GetProperty()->SetDiffuseColor(255, 255, 0);

    renderWindow->AddRenderer(renderer);
    renderer->AddActor(actor);
    renderer->ResetCamera();

    renderWindow->Render();

    // Add Timer Event...
    vtkSmartPointer<vtkCallbackCommand> timerCallback = vtkSmartPointer<vtkCallbackCommand>::New();
    timerCallback->SetCallback(TimerCallbackFunction);

    rwi->Initialize();
    rwi->CreateRepeatingTimer(100);
    rwi->AddObserver(vtkCommand::TimerEvent, timerCallback);


    // Start Displaying...
    rwi->Start();

    return 0;
}