float cX, cY, r, y, deltaY, orig, om, t, sp, h;

void setup() 
{
  size(600,600); smooth(); colorMode(HSB,360,100,100);
  frameRate(30); cX=width/2; cY=height/2; sp=width/14.0; 
  om=5; t=0; h=0;
}

void draw() 
{
  t+=1/30.0; orig = om*(1+cos(0.2*t))/2;
  deltaY=2*orig; background(255); fill(0);
  h=(h+0.1)%360;
  for(y=-cY; y<cY; y=y+sp){
    stroke(0); fill(h,75,100-70*(cY+y)/height);
    rect(0,cY+y,width,sp);
    noStroke(); fill(0);
    rect(0,cY+y-deltaY/4,width,deltaY/2);}

  for(r=6.5*sp; r>sp; r-=sp){
    for(y=-cY; y<cY; y=y+sp){
     if(abs(y)+om<r){
       beginShape();
       vertex(cX+sqrt(pow(r,2)-pow(y-deltaY,2)),cY+y-deltaY);
       vertex(cX+sqrt(pow(r,2)-pow(y,2)),cY+y);
       vertex(cX+sqrt(pow(r,2)-pow(y+deltaY,2)),cY+y+deltaY);
       vertex(cX-sqrt(pow(r,2)-pow(y+deltaY,2)),cY+y+deltaY);
       vertex(cX-sqrt(pow(r,2)-pow(y,2)), cY+y);
       vertex(cX-sqrt(pow(r,2)-pow(y-deltaY,2)),cY+y-deltaY);
     endShape(CLOSE);}
    }
    deltaY+=orig;
  }
}