qt 如何用vtk和三个空间点绘制一个平面

要在Qt中使用VTK来绘制一个平面，你可以按照以下步骤：

1. 在Qt项目中添加VTK库，包括头文件和链接库。

2. 创建一个vtkRenderer对象和vtkRenderWindow对象，并将vtkRenderWindow设置为Qt的QWidget。

vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
vtkRenderWindowInteractor* iren = vtkRenderWindowInteractor::New();
renderWindow->AddRenderer(renderer);
iren->SetRenderWindow(renderWindow);
vtkSmartPointer<vtkGenericOpenGLRenderWindow> widget = vtkSmartPointer<vtkGenericOpenGLRenderWindow>::New();
widget->SetRenderWindow(renderWindow);

3. 创建三个空间点以定义平面，并使用vtkPlaneSource类来创建平面poly data。

vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
points->InsertNextPoint(0.0, 0.0, 0.0);
points->InsertNextPoint(1.0, 0.0, 0.0);
points->InsertNextPoint(0.0, 1.0, 0.0);
vtkSmartPointer<vtkPlaneSource> planeSource = vtkSmartPointer<vtkPlaneSource>::New();
planeSource->SetOrigin(points->GetPoint(0));
planeSource->SetPoint1(points->GetPoint(1));
planeSource->SetPoint2(points->GetPoint(2));
planeSource->Update();
vtkPolyData* planePolyData = planeSource->GetOutput();

4. 创建vtkPolyDataMapper对象和vtkActor对象，并将平面poly data映射到vtkActor上。

vtkSmartPointer<vtkPolyDataMapper> planeMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
planeMapper->SetInputData(planePolyData);
vtkSmartPointer<vtkActor> planeActor = vtkSmartPointer<vtkActor>::New();
planeActor->SetMapper(planeMapper);

5. 将vtkActor添加到vtkRenderer中，并设置相机位置和方向。

renderer->AddActor(planeActor);
renderer->SetBackground(0.1, 0.2, 0.4);
renderer->ResetCamera();
renderer->GetActiveCamera()->Azimuth(30);
renderer->GetActiveCamera()->Elevation(30);
renderer->GetActiveCamera()->Dolly(1.5);
renderer->ResetCameraClippingRange();

6. 启动渲染循环。

iren->Initialize();
renderWindow->Render();
iren->Start();

完整的代码如下：

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkGenericOpenGLRenderWindow.h>
#include <vtkPlaneSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkPoints.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>

int main(int argc, char** argv)
{
    vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
    vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
    vtkRenderWindowInteractor* iren = vtkRenderWindowInteractor::New();
    renderWindow->AddRenderer(renderer);
    iren->SetRenderWindow(renderWindow);
    vtkSmartPointer<vtkGenericOpenGLRenderWindow> widget = vtkSmartPointer<vtkGenericOpenGLRenderWindow>::New();
    widget->SetRenderWindow(renderWindow);

    vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
    points->InsertNextPoint(0.0, 0.0, 0.0);
    points->InsertNextPoint(1.0, 0.0, 0.0);
    points->InsertNextPoint(0.0, 1.0, 0.0);
    vtkSmartPointer<vtkPlaneSource> planeSource = vtkSmartPointer<vtkPlaneSource>::New();
    planeSource->SetOrigin(points->GetPoint(0));
    planeSource->SetPoint1(points->GetPoint(1));
    planeSource->SetPoint2(points->GetPoint(2));
    planeSource->Update();
    vtkPolyData* planePolyData = planeSource->GetOutput();

    vtkSmartPointer<vtkPolyDataMapper> planeMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    planeMapper->SetInputData(planePolyData);
    vtkSmartPointer<vtkActor> planeActor = vtkSmartPointer<vtkActor>::New();
    planeActor->SetMapper(planeMapper);

    renderer->AddActor(planeActor);
    renderer->SetBackground(0.1, 0.2, 0.4);
    renderer->ResetCamera();
    renderer->GetActiveCamera()->Azimuth(30);
    renderer->GetActiveCamera()->Elevation(30);
    renderer->GetActiveCamera()->Dolly(1.5);
    renderer->ResetCameraClippingRange();

    iren->Initialize();
    renderWindow->Render();
    iren->Start();

    return 0;
}