/* Slow version of tuesday's floodfill example
 * This will take a break and display the image once every 100 pixels processed
 * Note that since a pixel is always taken from the end of tocheck, it will proceed
 * rightward first, since the rightmost neighbor is added to tocheck last. 
 * tocheck is operating as a stack, where the first item processed is the last inserted.
 * This is LIFO - last in, first out.  If it was FIFI - first in, first out, then the
 * fill would proceed outward from a central point.
 */
PImage img;
void setup() {
  img = loadImage("spiralthing.png");
  image(img, 0, 0);
  size(1000, 1000);
}
void draw() {
  image(img, 0, 0);
  decount = 0;
  ff_continue();
  
}

int qsize = 0;
int qbegin = 0;
void qin(int newp){
	tocheck[qbegin + qsize++] = newp;
}
int qout(){
	qsize--;
	return tocheck[qbegin++];
}
int tocheck[] = new int[100000]; // This is 400 KB of space.  That used to be a lot!
int decount = 0;
void ff_continue() {
  while (tcsize > 0) {
    if (decount > 100) {
      break;
    }
    decount++;
    // Check to see if the last pixel in tocheck needs to be filled
    // If not, move on to the next pixel
    // If so, add the neighbors to tocheck if they need to be filled
    tcsize--;
    int curr = tocheck[tcsize];
    if (red(img.pixels[curr]) < 128) {
      img.pixels[curr] = color(255, 100, 100);
      img.updatePixels();
      if (curr - width > 0 && red(img.pixels[curr - width]) < 128 ) {
        tocheck[tcsize] = curr - width;
        tcsize++;
      }
      if (curr + width < (height * width) && red(img.pixels[curr + width]) < 128 ) {
        tocheck[tcsize] = curr + width;
        tcsize++;
      }
      if (curr - 1 > 0 && red(img.pixels[curr - 1]) < 128 ) {
        tocheck[tcsize] = curr - 1;
        tcsize++;
      }
      if (curr + 1 < width*height && red(img.pixels[curr + 1]) < 128 ) {
        tocheck[tcsize] = curr + 1;
        tcsize++;
      }
    }
  }
  img.updatePixels();
}

void floodFill(int x, int y) {
  img.loadPixels();
  int startpoint = x + y*width;
  tocheck[0] = startpoint;
  tcsize = 1;
}
void mouseClicked() {
  floodFill(mouseX, mouseY);
}