WITH THIS FORMULA YOU CAN DRAW A POLYGONAL SPIRAL

THE MORE SIDES YOU ADD, THE ROUNDER THE SHAPE

var sides 			= 	3;
var fragment 		= 	Math.PI*2/sides;
var scale 			= 	3;
var start 			=   0;
var amount 			= 	30;
var inc 			= 	1;
for (var i=start; i<start+amount; i+=inc) {
 var sine 		= 	Math.sin(	i*fragment  );
  var cosine 		= 	Math.cos(	i*fragment  );
  
  var sine1 		= 	Math.sin(	i*fragment 	+ fragment  );
  var cosine1 	= 	Math.cos(	i*fragment 	+ fragment  );
  
  var radius 		= 	i*fragment*scale/inc ;
  var radius1 	= 	(i*fragment + fragment)*scale/inc ;
 var cx 			= 	canvas.width/2;
  var cy 			= 	canvas.height/2;
  
  var x 			= 	cx + radius * cosine ;
  var y 			= 	cy + radius * sine  ;
  
  var x1 			= 	cx + radius1 * cosine1 ;
  var y1 			= 	cy + radius1 * sine1 ;
  
  context.beginPath(); 
  context.lineTo(	x,	y	);
  context.lineTo(x1, y1);
  context.stroke();
  context.closePath();
}