FORM+CODE in Design, Art, and Architecture

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Transform: SLIT-SCAN

Contributed Examples

• OpenFrameworks

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  /**
   * Transform: SlitScan from Form+Code in Design, Art, and Architecture 
   * implemented in OpenFrameworks by Anthony Stellato <http://rabbitattack.com/> 
   * 
   * Requires OpenFrameworks available at http://openframeworks.cc/
   *
   * For more information about Form+Code visit http://formandcode.com
   */
  
  // ===========================================================
  // - Transform_SlitScan.h
  // ===========================================================
  #include "ofMain.h"
  
  class testApp : public ofBaseApp{
  
    public:
      void setup();
      void update();
      void draw();
      void setPixel(int horizontal,int vertical,unsigned char R,
              unsigned char G,unsigned char B,int w, unsigned char pixels[]);
      void getPixel(int horizontal,int vertical,unsigned char* R,
              unsigned char* G,unsigned char* B,int w, unsigned char pixels[]);
    
      ofVideoPlayer player;
      ofTexture texture;
      unsigned char * texpixels, * vidpixels;
  };
  
  
  // ===========================================================
  // - Transform_SlitScan.cpp
  // ===========================================================
  #include "Transform_SlitScan.h"
  
  int video_width     = 160;
  int video_height    = 120;
  int video_slice_x   = video_width/2;
  int window_width    = 1000;
  int window_height   = video_height;
  int draw_position_x = 0;
  bool newFrame  = false;
  
  //--------------------------------------------------------------
  void testApp::setup(){
    player.loadMovie("station.mov");
    player.setLoopState(1);
    player.play();
    
    texture.allocate(window_width, window_height, GL_RGB);
    texpixels = new unsigned char [window_width * window_height * 3];
  }
  
  //--------------------------------------------------------------
  void testApp::update(){
    player.idleMovie();
    newFrame = player.isFrameNew();
    if(newFrame){
      vidpixels = player.getPixels();
      for (int y=0; y<window_height; y++){
        unsigned char r, g, b;
        getPixel(video_slice_x, y, &r, &g, &b, video_width, vidpixels);
        setPixel(draw_position_x, y, r, g, b, window_width, texpixels);
      }
      texture.loadData(texpixels, window_width, window_height, GL_RGB);
      
      draw_position_x++;
      if (draw_position_x >= window_width) {
        OF_EXIT_APP(0);
      }
      newFrame = false;
    }
  }
  
  //--------------------------------------------------------------
  void testApp::draw(){
    ofBackground(0, 0, 0);
    texture.draw(0, 0);
  }
  
  // The following code is from the Pixel by Pixel Openframeworks Course
  // and is very useful if I do say myself.
  //--------------------------------------------------------------
  void testApp::setPixel(int horizontal,int vertical,unsigned char R,unsigned char G,
               unsigned char B,int w, unsigned char pixels[]){
    int thisPixel;
    thisPixel = 3*(w * vertical +horizontal);
    pixels[thisPixel]=R;
    pixels[thisPixel+1]=G;
    pixels[thisPixel+2]=B;
  }
  
  //--------------------------------------------------------------
  void testApp::getPixel(int horizontal,int vertical,unsigned char* R,unsigned char* G,
               unsigned char* B,int w, unsigned char pixels[]){
    int thisPixel;
    thisPixel = 3*(w * vertical +horizontal);
    *R= pixels[thisPixel];
    *G= pixels[thisPixel+1];
    *B= pixels[thisPixel+2];
  }
  

• Cinder

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  /**
   * Transform: Slit-Scan from Form+Code in Art, Design, and Architecture
   * implemented in C++ by Patrick Tierney <http://ptierney.com>
   *
   * A variation of this example by Forrest Oliphant <http://sembiki.com>
   * which takes advantage of cinder specific optimizations
   * can be found at https://gist.github.com/856451
   *
   * Requires Cinder 0.8.2 available at http://libcinder.org
   *
   * Project files are located at https://github.com/hlp/form-and-code
   *
   * For more information about Form+Code visit http://formandcode.com
   */
  
  #include "cinder/app/AppBasic.h"
  #include "cinder/Surface.h"
  #include "cinder/Capture.h"
  
  class Transform_SlitScan : public ci::app::AppBasic {
  public:
      void prepareSettings(Settings* settings);
      void setup();
      void update();
      void draw();
      void shutdown();
  
  private:
      ci::Capture capture;
      ci::Surface surface;
  
      int video_width;
      int video_height;
      int video_slice_x;
      int window_width;
      int window_height;
      int draw_position_x;
      bool newFrame;
  
      int data_size;
      GLubyte* data;
  };
  
  void Transform_SlitScan::prepareSettings(Settings* settings) {
      video_width = 320;
      video_height = 240;
      video_slice_x = video_width / 2;
      window_width = 1000;
      window_height = video_height;
      draw_position_x = 0;
      newFrame = false;
      data_size = window_width * window_height * 3;
  
      settings->setWindowSize(window_width, window_height);
  }
  
  void Transform_SlitScan::setup() {
      try {
          capture = ci::Capture(video_width, video_height);
          capture.start();
      } catch (...) {
          // if we threw in the start close the program 
          ci::app::console() << "Unable to open webcam." << std::endl;
          exit(1);
      }
  
      if (capture.getWidth() != video_width || capture.getHeight() != video_height) {
          ci::app::console() << "Unable to open webcam at desired size." << std::endl;
          exit(1);
      }
  
      // create new pixel buffer
      data = new GLubyte[data_size];
  
      // set all pixels to black
      for (int i = 0; i < data_size; ++i) {
          data[i] = (GLubyte) 0;
      }
  }
  
  void Transform_SlitScan::update() {
      newFrame = false;
  
      if (!capture || !capture.checkNewFrame()) 
          return;
  
      newFrame = true;
  
      surface = capture.getSurface();
  
      ci::Surface::Iter it = surface.getIter();
  
      int i = window_height - 1;
      while(it.line()) {
          int j = 0;
      while(it.pixel()) {
              if (j == video_slice_x) {
                  data[i * window_width * 3 + draw_position_x * 3] = (GLubyte) it.r(); 
                  data[i * window_width * 3 + draw_position_x * 3 + 1] = (GLubyte) it.g(); 
                  data[i * window_width * 3 + draw_position_x * 3 + 2] = (GLubyte) it.b(); 
              }
              j++;
      }
          i--;
    }
  }
  
  void Transform_SlitScan::draw() {
      if (!newFrame)
          return;
  
      draw_position_x++;
  
      if (draw_position_x >= window_width)
          draw_position_x = 0;
  
      glDrawPixels(window_width, window_height, GL_RGB, GL_UNSIGNED_BYTE, data);
  }
  
  void Transform_SlitScan::shutdown() {
      delete [] data;
  }
  
  
  CINDER_APP_BASIC(Transform_SlitScan, ci::app::RendererGl)
  

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