- (void)drawRect:(CGRect)rect {
    switch (_state) {
        case SRSlimeStateNormal:
        {
            float percent = 1 - distansBetween(_startPoint , _toPoint) / _viscous;
            if (percent == 1) {
                CGContextRef context = UIGraphicsGetCurrentContext();
                UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(_startPoint.x - _radius, _startPoint.y - _radius, 2*_radius, 2*_radius)
                                                                cornerRadius:_radius];
                [self setContext:context path:path];
                CGContextDrawPath(context, kCGPathFillStroke);
            }else {
                CGFloat startRadius = _radius * (kStartTo + (1-kStartTo)*percent);
                CGFloat endRadius = _radius * (kEndTo + (1-kEndTo)*percent);
                CGContextRef context = UIGraphicsGetCurrentContext();
               
                UIBezierPath *path = [self bodyPath:startRadius
                                                end:endRadius
                                            percent:percent];
                [self setContext:context path:path];
                CGContextDrawPath(context, kCGPathFillStroke);
                if (percent <= 0) {
                    _state = SRSlimeStateShortening;
                    [self scaling];
                }
            }
        }
            break;
        case SRSlimeStateShortening:
        {
            _toPoint = CGPointMake((_toPoint.x - _startPoint.x)*0.8 + _startPoint.x,
                                       (_toPoint.y - _startPoint.y)*0.8 + _startPoint.y);
            float p = distansBetween(_startPoint, _toPoint) / _viscous;
            float percent =1 -p;
            float r = _radius * p;
           
            if (p > 0.01) {
                CGFloat startRadius = r * (kStartTo + (1-kStartTo)*percent);
                CGContextRef context = UIGraphicsGetCurrentContext();
               
                CGFloat endRadius = r * (kEndTo + (1-kEndTo)*percent) * (1+percent / 2);
                UIBezierPath *path = [self bodyPath:startRadius
                                                end:endRadius
                                            percent:percent];
                [self setContext:context path:path];
                CGContextDrawPath(context, kCGPathFillStroke);
            }else {
                self.hidden = YES;
                _state = SRSlimeStateMiss;
            }
        }
            break;
        default:
            break;
    }

}