VTK_Learning_坐标系统及空间变换(窗口-视图分割)

矫情吗；* 2023-06-27 03:14 28阅读 0赞

# 1.VTK坐标系统 #

> 计算机图形学里常用的坐标系统主要有四种，分别是：Model坐标系统、World坐标系统、View坐标系统和Display坐标系统，以及两种表示坐标点的方式：以屏幕像素值为单位和归一化坐标值(各坐标轴取值都为\[-1, 1\])。  
> Model坐标系统是定义模型时所采用的坐标系统，通常是局部的笛卡尔坐标系。例如，我们要定义一个表示球体的Actor，一般的做法是将该球体定义在一个柱坐标系统里。  
> World坐标系统是放置Actor的三维空间坐标系，Actor其中的一个功能就是负责将模型从Model坐标系统变换到World坐标系统。每一个模型可以定义有自己的Model坐标系统，但World坐标系只有一个，每一个Actor必须通过放缩、旋转、平移等操作将Model坐标系变换到World坐标系。World坐标系同时也是相机和光照所在的坐标系统。  
> View坐标系统表示的是相机所看见的坐标系统。X、Y、Z轴取值为\[-1, 1\]，X、Y值表示像平面上的位置，Z值表示到相机的距离。相机负责将World坐标系变换到View坐标系。
> 
> 坐标之间的关系如下图所示：  
> ![20161125213209961][]
> 
> Display坐标系统跟View坐标系统类似，但是各坐标轴的取值不是\[-1, 1\]，而是使用屏幕像素值。屏幕上显示的不同窗口的大小会影响View坐标系的坐标值\[-1, 1\]到Display坐标系的映射。可以把不同的渲染场景放在同一个窗口进行显示，例如，在一个窗口里，分为左右两个渲染场景，这左右的渲染场景(vtkRenderer)就是不同的视口(Viewport)。
> 
>   
>

#  2.一个窗口分割为多个视窗 #

#include <vtkAutoInit.h>
    VTK_MODULE_INIT(vtkRenderingOpenGL2);
    #include <vtkConeSource.h>
    #include <vtkCubeSource.h>
    #include <vtkCylinderSource.h>
    #include <vtkSphereSource.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkActor.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkSmartPointer.h>
    
    int main()
    {
        vtkSmartPointer<vtkConeSource> cone = vtkSmartPointer<vtkConeSource>::New();
        vtkSmartPointer<vtkCubeSource> cube = vtkSmartPointer<vtkCubeSource>::New();
        vtkSmartPointer<vtkCylinderSource> cylinder = vtkSmartPointer<vtkCylinderSource>::New();
        vtkSmartPointer<vtkSphereSource> sphere = vtkSmartPointer<vtkSphereSource>::New();
    
        vtkSmartPointer<vtkPolyDataMapper> coneMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
        coneMapper->SetInputConnection(cone->GetOutputPort());
        vtkSmartPointer<vtkPolyDataMapper> cubeMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
        cubeMapper->SetInputConnection(cube->GetOutputPort());
        vtkSmartPointer<vtkPolyDataMapper> cylinderMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
        cylinderMapper->SetInputConnection(cylinder->GetOutputPort());
        vtkSmartPointer<vtkPolyDataMapper> sphereMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
        sphereMapper->SetInputConnection(sphere->GetOutputPort());
    
        vtkSmartPointer<vtkActor> coneActor = vtkSmartPointer<vtkActor>::New();
        coneActor->SetMapper(coneMapper);
        vtkSmartPointer<vtkActor> cubeActor = vtkSmartPointer<vtkActor>::New();
        cubeActor->SetMapper(cubeMapper);
        vtkSmartPointer<vtkActor> cylinderActor = vtkSmartPointer<vtkActor>::New();
        cylinderActor->SetMapper(cylinderMapper);
        vtkSmartPointer<vtkActor> sphereActor = vtkSmartPointer<vtkActor>::New();
        sphereActor->SetMapper(sphereMapper);
    
        vtkSmartPointer<vtkRenderer> renderer1 = vtkSmartPointer<vtkRenderer>::New();
        renderer1->AddActor(coneActor);
        renderer1->SetBackground(1.0,0.0,0.0);
        renderer1->SetViewport(0.0,0.0,0.5,0.5);
        vtkSmartPointer<vtkRenderer> renderer2 = vtkSmartPointer<vtkRenderer>::New();
        renderer2->AddActor(cubeActor);
        renderer2->SetBackground(0.0,1.0,0.0);
        renderer2->SetViewport(0.5,0.0,1.0,0.5);
        vtkSmartPointer<vtkRenderer> renderer3 = vtkSmartPointer<vtkRenderer>::New();
        renderer3->AddActor(cylinderActor);
        renderer3->SetBackground(0.0,0.0,1.0);
        renderer3->SetViewport(0.0,0.5,0.5,1.0);
        vtkSmartPointer<vtkRenderer> renderer4 = vtkSmartPointer<vtkRenderer>::New();
        renderer4->AddActor(sphereActor);
        renderer4->SetBackground(1.0,1.0,0.0);
        renderer4->SetViewport(0.5,0.5,1.0,1.0);
    
        vtkSmartPointer<vtkRenderWindow> renWin = vtkSmartPointer<vtkRenderWindow>::New();
        renWin->AddRenderer(renderer1);
        renWin->AddRenderer(renderer2);
        renWin->AddRenderer(renderer3);
        renWin->AddRenderer(renderer4);
        renWin->SetSize( 640, 480 );
        renWin->Render();
        renWin->SetWindowName("ViewPort");
    
        vtkSmartPointer<vtkRenderWindowInteractor> interactor =
            vtkSmartPointer<vtkRenderWindowInteractor>::New();
        interactor->SetRenderWindow(renWin);
    
        renWin->Render();
        interactor->Initialize();
        interactor->Start();
    
        return EXIT_SUCCESS;
    
    }

# 3.运行结果： #

![20161125215447327][]

# 4.总结视图 #

> 一张图可以考验之前学过的知识是否真正的理解了！

![20161125220114425][]

[20161125213209961]: https://img-blog.csdn.net/20161125213209961
[20161125215447327]: https://img-blog.csdn.net/20161125215447327
[20161125220114425]: https://img-blog.csdn.net/20161125220114425