Rolling dragon curve

pic_transform.pde

// Source for 'rolling dragon curve', amiagoodperson.tumblr.com

import java.io.FilenameFilter;

int w, h;
int count = 0;
int fps = 15;

// Replace this directory with one containing the frames of 'dragon curve' as PNGs
// (gif at) http://amiagoodperson.tumblr.com/post/64585437717/such-fractal-many-unoriginal
String sourceDir = "C:/path/to/png/images";
PImage[] images;
PImage current;

String filename = "dragoncurve_roll";
int saveFreq = 1;

void setup()
{
  size(500, 500);
  w = width;
  h = height;
  colorMode(HSB);
  ellipseMode(RADIUS);
  frameRate(fps);
  loadImages();
}
void loadImages()
{
  File dir = new File(sourceDir);
  File[] pictures = dir.listFiles(new FilenameFilter() {
    public boolean accept(File f, String s)
    {
      //gen.png is used as 'source pattern' picture in linefractalgen
      return s.contains(".png") && !s.equals("gen.png"); // too lazy to check if this .png is terminal
    }
  });
  if(pictures == null)
  {
    println(sourceDir + " is not a directory!");
    return;
  }
  images = new PImage[pictures.length];
  try
  {
    for(int i = 0; i < pictures.length; i++)
    {
      images[i] = loadImage(pictures[i].getCanonicalPath());
      images[i].loadPixels();
    }
    println("Found " + images.length + " png images.");
    println("First image is " + images[0].width + "x" + images[0].height);
    size(images[0].width, images[0].height);
  }
  catch (Exception e)
  {
    println("Images didn't load!");
    e.printStackTrace();
  }
  current = new PImage(width, height);
  current.loadPixels();
}
String mode = "select";
void transform()
{
  if(mode.equals("select"))
    selector();
}
void selector()
{
  int mode = 1;
  int multiplier = -3;
  //todo: component offsets
  
  int switchFreq = (int)Math.ceil(1.0 * w*h/images.length);
  int whichImg = count;
  int j;
  for(int i = 0; i < width*height; i++)
  {
    j = i;
    if(multiplier < 0)
      j = -(width*height - i);
    switch(mode)
    {
      case 1: //continguous block of pixels is selected from the same image
        whichImg = (count + multiplier * j/switchFreq) % images.length;
        break;
      case 2: //changes every pixel
        whichImg = (count + multiplier * j) % images.length;
        break;
      case 3: //radiates from centre
        whichImg = (count + abs(multiplier) * distSq(i)) % images.length;
        break;
      default:
        whichImg = count;
    }
    current.pixels[i] = images[whichImg].pixels[i];
  }
  current.updatePixels();
}
int distSq(int index)
{
  int x = index % width;
  int y = index / width;
  return (int)sq(x - width/2) + (int)sq(y - height/2);
}
//argb == 3210
int component(color c, int which)
{
  return (c << (8*which)) & 0xFF;
}
void draw()
{
  background(0);
  count++;
  
  transform();
  image(current, 0, 0);
  //image(images[count % images.length], 0, 0);
  
  if(filename.length() > 0 && count % saveFreq == 0 && count <= images.length)
    save(filename + filename(count/saveFreq) + ".png");
}
String filename(int i)
{
  if(i > 26)
    return 'z' + filename(i - 26);
  return ""+(char)('a'+i-1);
}