var opp=this.start.y-this.control.y; var adj=this.start.x-this.control.x; if(!adj) adj=1; this.startRotation=Math.atan(opp/adj); opp=this.control.y-this.end.y; adj=this.control.x-this.end.x; if(!adj) adj=1; this.endRotation=Math.atan(opp/adj);