code: function expand( v1, v2, pixels ) {
  
  		var x = v2.x - v1.x, y = v2.y - v1.y,
  		det = x * x + y * y, idet;
  
  		if ( det === 0 ) return;
  
  		idet = pixels / Math.sqrt( det );
  
  		x *= idet; y *= idet;
  
  		v2.x += x; v2.y += y;
  		v1.x -= x; v1.y -= y;
  
  	}
docs: Hide anti-alias gaps