/*

   Structure 3 (work in progress)

   A surface filled with one hundred medium to small sized circles.
   Each circle has a different size and direction, but moves at the same slow rate.
   Display:
   A. The instantaneous intersections of the circles
   B. The aggregate intersections of the circles

   Implemented by Casey Reas <http://groupc.net>
   Uses circle intersection code from William Ngan <http://metaphorical.net>
   Processing v.68 <http://processing.org>

*/

int numCircle = 100;
Circle[] circles = new Circle[numCircle];

void setup()
{
  size(640, 480);
  framerate(30);
  for(int i=0; i<numCircle; i++) {
    circles[i] = new Circle(random(width), random(height), random(2, 6)*10,
                            random(-2.0, 2.0), random(-2.0, 2.0));
  }
  ellipseMode(CENTER_DIAMETER);
  background(255);
}


void loop()
{
  background(255);

  for(int i=0; i<numCircle; i++) {
    circles[i].move();
  }
}


class Circle {

  float x, y, r, sp, ysp;

  Circle( float px, float py, float pr, float psp, float pysp) {
    x = px;
    y = py;
    r = pr;
    sp = psp;
    ysp = pysp;
  }

  void move() {
    x += sp;
    y += ysp;
    if(sp > 0) {
      if(x > width+r) {
        x = -r;
      }
    } else {
      if(x < -r) {
        x = width+r;
      }
    }
    if(ysp > 0) {
      if(y > height+r) {
        y = -r;
      }
    } else {
      if(y < -r) {
        y = height+r;
      }
    }

    stroke(0);
    noFill();
    ellipse(x, y, r, r);
  }
}