Negative ellipses

int w = 500;

int h = 500;

int framerate = 30;

float x = -w/2;

float y = +h/2;

float x1 = -w/2;

float y1 = -h/2;

​

void setup() {

  size(w,h);

  frameRate(framerate);

  fill(180, 180, 180); 

  noStroke();  

}

​

void draw() {

 fill(180, 180, 180); 

 background(131, 131, 131);

 ellipse(width/2,height/2,width/2+x,height/2+y);

 ellipse(width/2,height/2,width/2+y,height/2+x);

 if(width/2+x > width*2-width/2) {

   fill(131, 131, 131);

   ellipse(width/2,height/2,width/2+x1,height/2+y1);

   ellipse(width/2,height/2,width/2+y1,height/2+x1);

   x1 += 15;

   y1 -= 15;

 }

​

 x += 15;

 y -= 15;

}