問題描述

vtk中顯示模型的各個檢視，例如前檢視、後檢視、左檢視、右檢視等。

解析

我們通過調整相機位置、焦點位置、朝上方向來實現各個檢視。

• 相機位置：即相機所在的位置，用方法vtkCamera::SetPosition()設定；
• 相機焦點：從相機看向的點，用方法vtkCamera::SetFocusPoint()設定；
• 朝上方向：相機朝上的方向。就好比我們直立看東西，方向為頭朝上，看到的東西也是直立的，如果我們倒立看某個東西，這時方向為頭朝下，看到的東西當然就是倒立的。相機位置、相機焦點和朝上方向三個因素確定了相機的實際方向，即確定相機的檢視。

放置幾個模型：

各個檢視：

實現

#include <vtkSmartPointer.h>
#include <vtkCameraActor.h>
#include <vtkNamedColors.h>
#include <vtkSphereSource.h>
#include <vtkConeSource.h>
#include <vtkCubeSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkCamera.h>
#include <vtkMapper.h>
 

#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>

void ViewDirection(vtkRenderer *renderer,
                   double lookX, double lookY, double lookZ,
                   double upX, double upY, double upZ)
{
    renderer->GetActiveCamera()->SetPosition(0
 
, 0, 0);    //相機位置
    renderer->GetActiveCamera()->SetFocalPoint(lookX, lookY, lookZ);    //焦點位置
    renderer->GetActiveCamera()->SetViewUp(upX, upY, upZ);    //朝上方向
    renderer->ResetCamera();
}

void ViewPositiveX(vtkRenderer *renderer)
{
    ViewDirection(renderer, 1, 0, 0, 0, 0, 1);
}

void ViewNegativeX(vtkRenderer *renderer)
{
    ViewDirection(renderer, -1, 0, 0, 0, 0, 1);
}

void ViewPositiveY(vtkRenderer *renderer)
{
    ViewDirection(renderer, 0, 1, 0, 0, 0, 1);
}

void ViewNegativeY(vtkRenderer *renderer)
{
    ViewDirection(renderer, 0, -1, 0, 0, 0, 1);
}

void ViewPositiveZ(vtkRenderer *renderer)
{
    ViewDirection(renderer, 0, 0, 1, 0, 1, 0);
}
void ViewNegativeZ(vtkRenderer *renderer)
{
    ViewDirection(renderer, 0, 0, -1, 0, 1, 0);
}

int main(int, char *[])
{
    auto namedColors = vtkSmartPointer<vtkNamedColors>::New();

    // X軸上放置立方體
    auto cubeSource = vtkSmartPointer<vtkCubeSource>::New();
    cubeSource->SetCenter(1000, 0, 0);
    cubeSource->SetXLength(1000);
    cubeSource->SetYLength(1000);
    cubeSource->SetZLength(1000);
    cubeSource->Update();

    auto cubeMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    cubeMapper->SetInputConnection(cubeSource->GetOutputPort());
    auto cubeActor = vtkSmartPointer<vtkActor>::New();
    cubeActor->SetMapper(cubeMapper);
    cubeActor->GetProperty()->SetDiffuseColor(
        namedColors->GetColor3d("Tomato").GetData());

    // Y軸放置圓球
    auto sphereSource = vtkSmartPointer<vtkSphereSource>::New();
    sphereSource->SetCenter(0, 1000, 0);
    sphereSource->SetRadius(500);
    sphereSource->SetThetaResolution(64);
    sphereSource->SetPhiResolution(64);
    sphereSource->Update();

    auto sphereMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    sphereMapper->SetInputConnection(sphereSource->GetOutputPort());
    auto sphereActor = vtkSmartPointer<vtkActor>::New();
    sphereActor->SetMapper(sphereMapper);
    sphereActor->GetProperty()->SetDiffuseColor(
        namedColors->GetColor3d("Tomato").GetData());

    // Z軸上放置圓錐
    auto coneSource = vtkSmartPointer<vtkConeSource>::New();
    coneSource->SetCenter(0, 0, 1000);
    coneSource->SetRadius(500);
    coneSource->SetHeight(1000);
    coneSource->SetDirection(0, 0, 1);
    coneSource->SetResolution(128);
    coneSource->Update();

    auto coneMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    coneMapper->SetInputConnection(coneSource->GetOutputPort());
    auto coneActor = vtkSmartPointer<vtkActor>::New();
    coneActor->SetMapper(coneMapper);
    coneActor->GetProperty()->SetDiffuseColor(
        namedColors->GetColor3d("Tomato").GetData());

    // Visualize
    auto renderer = vtkSmartPointer<vtkRenderer>::New();
    auto renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
    renderWindow->SetSize(500, 500);
    renderWindow->AddRenderer(renderer);

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

    renderer->SetBackground(namedColors->GetColor3d("SlateGray").GetData());
    renderer->AddActor(cubeActor);
    renderer->AddActor(sphereActor);
    renderer->AddActor(coneActor);
    renderer->ResetCamera();

    //ViewPositiveX(renderer);
    //ViewNegativeX(renderer);
    //ViewPositiveY(renderer);
    //ViewNegativeY(renderer);
    //ViewPositiveZ(renderer);
    ViewNegativeZ(renderer);

    renderWindow->Render();
    renderWindowInteractor->Start();

    return EXIT_SUCCESS;
}