VTK是什么

實(shí)際上是基于OpenGL的圖形開發(fā)函數(shù)庫。

• OpenGL + OOP
• C++作為核心， 有Tcl、Python、Java的接口
• 支持多種數(shù)據(jù)類型
• Open Source

VTK典型流程

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

直觀流程

程序流程.png

左邊一縱列對應(yīng)Data --> Gemoetry
右邊一縱列對應(yīng)Gemotry --> Image

Data --> Geometry

包括vtkSource, vtkFilter, vtkMapper

• vtkSource : 各類圖形的數(shù)字構(gòu)成，以及各種圖像文件的讀寫數(shù)據(jù)等
• vtkFilter : 以數(shù)據(jù)對象作為輸入，輸出處理后的數(shù)據(jù)對象。實(shí)現(xiàn)各種圖像處理算法。
• vtkMapper : 將Data轉(zhuǎn)換為Gemoetry數(shù)據(jù)，作為下一步顯示的圖形來源。vtkMapper接收Filter的輸入，但不產(chǎn)生輸出。整體作為下一步處理的基礎(chǔ)。

Geometry --> Image

包括vtkActor, vtkRenderer, vtkRenderWindow

Geometry --> Image

• vtkActor : 代表了一個在場景中被渲染的物體，例如一個錐體或一個立方體，自身可以設(shè)定多個屬性，如坐標(biāo)、旋轉(zhuǎn)角度、表明材質(zhì)、反光效果、透明度等等
• vtkRenderer : 負(fù)責(zé)渲染物體的進(jìn)程，可以設(shè)置顯示角度、光照角度等等屬性
• vtkRenderWindow : 在操作系統(tǒng)上顯示的一個窗口，可以包含一個或者多個vtkRenderer，上圖中左邊那個窗口中就有兩個Renderer

整體流水線

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;
}