VTK是什么

实际上是基于OpenGL的图形开发函数库。

• OpenGL + OOP
• C++作为核心， 有Tcl、Python、Java的接口
• 支持多种数据类型
• Open Source

VTK典型流程

** Data --> Geometry --> Image **

直观流程

程序流程.png

左边一纵列对应Data --> Gemoetry
右边一纵列对应Gemotry --> Image

Data --> Geometry

包括vtkSource, vtkFilter, vtkMapper

• vtkSource : 各类图形的数字构成，以及各种图像文件的读写数据等
• vtkFilter : 以数据对象作为输入，输出处理后的数据对象。实现各种图像处理算法。
• vtkMapper : 将Data转换为Gemoetry数据，作为下一步显示的图形来源。vtkMapper接收Filter的输入，但不产生输出。整体作为下一步处理的基础。

Geometry --> Image

包括vtkActor, vtkRenderer, vtkRenderWindow

Geometry --> Image

• vtkActor : 代表了一个在场景中被渲染的物体，例如一个锥体或一个立方体，自身可以设定多个属性，如坐标、旋转角度、表明材质、反光效果、透明度等等
• vtkRenderer : 负责渲染物体的进程，可以设置显示角度、光照角度等等属性
• vtkRenderWindow : 在操作系统上显示的一个窗口，可以包含一个或者多个vtkRenderer，上图中左边那个窗口中就有两个Renderer

整体流水线

Pipeline.png

Example

/*=========================================================================

  Program:   Visualization Toolkit
  Module:    Cone.cxx

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
//
// This example creates a polygonal model of a cone, and then renders it to
// the screen. It will rotate the cone 360 degrees and then exit. The basic
// setup of source -> mapper -> actor -> renderer -> renderwindow is
// typical of most VTK programs.
//

// First include the required header files for the VTK classes we are using.
#include "vtkConeSource.h"
#include "vtkPolyDataMapper.h"
#include "vtkRenderWindow.h"
#include "vtkCamera.h"
#include "vtkActor.h"
#include "vtkRenderer.h"

int main()
{
  //
  // Next we create an instance of vtkConeSource and set some of its
  // properties. The instance of vtkConeSource "cone" is part of a
  // visualization pipeline (it is a source process object); it produces data
  // (output type is vtkPolyData) which other filters may process.
  //
  vtkConeSource *cone = vtkConeSource::New();
  cone->SetHeight( 3.0 );
  cone->SetRadius( 1.0 );
  cone->SetResolution( 10 );

  //
  // In this example we terminate the pipeline with a mapper process object.
  // (Intermediate filters such as vtkShrinkPolyData could be inserted in
  // between the source and the mapper.)  We create an instance of
  // vtkPolyDataMapper to map the polygonal data into graphics primitives. We
  // connect the output of the cone souece to the input of this mapper.
  //
  vtkPolyDataMapper *coneMapper = vtkPolyDataMapper::New();
  coneMapper->SetInputConnection( cone->GetOutputPort() );

  //
  // Create an actor to represent the cone. The actor orchestrates rendering
  // of the mapper's graphics primitives. An actor also refers to properties
  // via a vtkProperty instance, and includes an internal transformation
  // matrix. We set this actor's mapper to be coneMapper which we created
  // above.
  //
  vtkActor *coneActor = vtkActor::New();
  coneActor->SetMapper( coneMapper );

  //
  // Create the Renderer and assign actors to it. A renderer is like a
  // viewport. It is part or all of a window on the screen and it is
  // responsible for drawing the actors it has.  We also set the background
  // color here.
  //
  vtkRenderer *ren1= vtkRenderer::New();
  ren1->AddActor( coneActor );
  ren1->SetBackground( 0.1, 0.2, 0.4 );

  //
  // Finally we create the render window which will show up on the screen.
  // We put our renderer into the render window using AddRenderer. We also
  // set the size to be 300 pixels by 300.
  //
  vtkRenderWindow *renWin = vtkRenderWindow::New();
  renWin->AddRenderer( ren1 );
  renWin->SetSize( 300, 300 );

  //
  // Now we loop over 360 degreeees and render the cone each time.
  //
  int i;
  for (i = 0; i < 360; ++i)
    {
    // render the image
    renWin->Render();
    // rotate the active camera by one degree
    ren1->GetActiveCamera()->Azimuth( 1 );
    }

  //
  // Free up any objects we created. All instances in VTK are deleted by
  // using the Delete() method.
  //
  cone->Delete();
  coneMapper->Delete();
  coneActor->Delete();
  ren1->Delete();
  renWin->Delete();

  return 0;
}