// 10PRINT tunnel-rosette Processing 3 code, thanks to @shiffman and @jmutterer!

10PRINT 'tunnel-rosette'.pde

// 10PRINT rosette Processing 3 code
// thanks to @shiffman and @jmutterer!

static float r=30;
static float s=10;

int i, j;
static int maxI = 60;
static int maxJ = 25;

float directions[][] = new float[maxJ][maxI];

void setup() {
  size(650, 650);
  frameRate(10);
  i = 0;
  j = 0;
}

void draw() {
  background(72, 58, 170);
  translate (width/2, height/2);
  scale (1, -1);
  strokeWeight(1.5);
  stroke (134, 122, 222);
  /*
  if(j < maxJ-1) i++;
  if (i == maxI){
    ++j;
    i = 0;
    println(j);
    //j == 13 hits borders
  }
  */
  j++;
  
  for(int i=0; i<maxI; ++i) {
    stroke (134, 122, 222, 255-15*j);
    float direction = (random(1)>0.5)?-1:1;
    directions[j][i] = direction;
  }
  
  
  for(int y = 0; y < j; ++y) {
    for(int x = 0; x < maxI && !(y == j && x > i); ++x) {
      stroke (134, 122, 222, 50+8*y);
      float a = (x-directions[y][x]/2)*2*PI/60;
      float b = (x+directions[y][x]/2)*2*PI/60;
      line ((r+(maxJ - y)*s)*sin(a), (r+(maxJ - y)*s)*cos(a), 
        (r+(maxJ - (y+1))*s)*sin(b), (r+(maxJ - (y+1))*s)*cos(b));
    }
  }
  if(j == maxJ - 1) {
    for(int y = 0; y < maxJ - 1; ++y) {
      for(int x = 0; x < maxI; ++x) {
        directions[y][x] = directions[y+1][x];
      }
    }
    j--;
    i = 0;
  }
}