/* built with Studio Sketchpad: 
 *   https://sketchpad.cc
 * 
 * observe the evolution of this sketch: 
 *   https://studio.sketchpad.cc/sp/pad/view/ro.0Hh4MHYBarq/rev.9
 * 
 * authors: 
 *   GoToLoop

 * license (unless otherwise specified): 
 *   creative commons attribution-share alike 3.0 license.
 *   https://creativecommons.org/licenses/by-sa/3.0/ 
 */ 



/**
 * Spiral Flow Field (v2.11)
 * by  TfGuy44 (2014/Oct/30)
 * mod GoToLoop
 *
 * forum.processing.org/two/discussion/7860/spiral-flow-field
 * studio.processingtogether.com/sp/pad/export/ro.9$u0c$3ioIJIw/latest
 */

static final int QTY = 5120, FPS = 60;
final Par[] pars = new Par[QTY];

void setup() {
  size(448, 448, JAVA2D);
  frameRate(FPS);
  noSmooth();

  for (int i = 0; i != QTY; pars[i++] = new Par());
}

void draw() {
  if  (!mousePressed)  background(0);
  for (Par p : pars)   p.display();
}

class Par {
  static final short HOLE = 32;
  static final float STEP = .05;
  static final color OFF  = -1, ON = #FF0000;

  final int cx, cy;
  float t = random(TWO_PI);

  Par() {
    float r = sq(random(sqrt(HOLE), sqrt(width/2 - HOLE)));
    cx = (int)(width/2  + r*cos(t));
    cy = (int)(height/2 + r*sin(t));
  }

  void display() {
    set(cx + (int)(HOLE*cos(t += STEP)), cy + (int)(HOLE*sin(t)), OFF);
    if (mousePressed)   set(cx, cy, ON);
  }
}