为了在svg多边形或圆形上具有两个笔触和模糊效果，我创建了一个过滤器来执行此操作，尽管第二个“笔划”（使用过滤器创建）被裁剪或不像是一个完美的圆。知道如何以正确的方式解决此问题吗？
<svg height="500" width="400">
<defs>
<filter id="select-highlight" width="200%" height="200%" x="-50%" y="-50%">
<feOffset in="SourceGraphic" dx="0" dy="0" result="offset"></feOffset>
<feMorphology in="offset" result="offsetmorph" operator="dilate" radius="2"></feMorphology>
<feFlood flood-color="white"></feFlood>
<feComposite operator="in" in2="offsetmorph" result="stroke"></feComposite>
<feGaussianBlur stdDeviation="5" result="offsetblur"></feGaussianBlur>
<feFlood flood-color="#4881D7"></feFlood>
<feComposite operator="in" in2="offsetblur" result="blur"></feComposite>
<feMerge>
<feMergeNode in="blur"></feMergeNode>
<feMergeNode in="stroke"></feMergeNode>
<feMergeNode in="SourceGraphic"></feMergeNode>
</feMerge>
</filter>
</defs>
<g transform="translate(50,50) scale(3)">
<polygon points=" 22,0
44,10
44,34
22,44
0,34
0,10" fill="#e6a6d5" stroke="#4881D7" stroke-width="2" filter="url(#select-highlight)"></polygon>
</g>
<g transform="translate(50,250) scale(3)">
<circle cx="22" cy="22" r="22" fill="#b6ccef" stroke="#4881D7" stroke-width="2" filter="url(#select-highlight)"></circle>
</g>
</svg>