Make a portion of a transparent svg opaque [duplicate] - css

Question

I have a jsfiddle here - http://jsfiddle.net/apbuc773/
I'd like to create a star using svg.
I'd like to stroke the outside of the star. In my example the stroke is on every line which dissects the inner shape.
Also is it possible to half fill the star shape.
I'd like to use this for a star rating but I need half and maybe quarter fills.
<svg height="210" width="500">
<polygon points="100,10 40,198 190,78 10,78 160,198" style="fill:red;stroke:blue;"/>
</svg>

Answer 1

You can alternatively do this with a filter. Here is one that animates the fill:
<svg height="210" width="500">
<defs>
<filter id="fillpartial" primitiveUnits="objectBoundingBox" x="0%" y="0%" width="100%" height="100%">
<feFlood x="0%" y="0%" width="100%" height="100%" flood-color="red" />
<feOffset dy="0.5">
<animate attributeName="dy" from="1" to=".5" dur="3s" />
</feOffset>
<feComposite operator="in" in2="SourceGraphic" />
<feComposite operator="over" in2="SourceGraphic" />
</filter>
</defs>
<polygon filter="url(#fillpartial)" points="165.000, 185.000, 188.511, 197.361, 184.021, 171.180,
203.042, 152.639,
176.756, 148.820,
165.000, 125.000,
153.244, 148.820,
126.958, 152.639,
145.979, 171.180,
141.489, 197.361,
165.000, 185.000" style="fill:white;stroke:red;" />
</svg>

Answer 2

Here is a example: http://jsfiddle.net/apbuc773/11/
Gradient can be used like this:
<svg height="210" width="500">
<defs>
<linearGradient id="half">
<stop offset="0%" stop-color="red" />
<stop offset="50%" stop-color="red" />
<stop offset="50%" stop-color="white" />
<stop offset="100%" stop-color="white" />
</linearGradient>
</defs>
<g fill="url(#half)" stroke="blue" stroke-width="2">
If you don't want to change your polygon points, just apply this polygon twice: one time with stroke and one time without.

Answer 3

I've noticed the comment of the accepted answer, and here is how you fill an custom shape:
<svg width="100" height="100" viewBox="0 0 100 100" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<defs>
<clipPath id="heart">
<path d="M81.495,13.923c-11.368-5.261-26.234-0.311-31.489,11.032C44.74,13.612,29.879,8.657,18.511,13.923 C6.402,19.539,0.613,33.883,10.175,50.804c6.792,12.04,18.826,21.111,39.831,37.379c20.993-16.268,33.033-25.344,39.819-37.379 C99.387,33.883,93.598,19.539,81.495,13.923z"/>
</clipPath>
</defs>
<rect x="0" y="0" fill="rgb(217,217,217)" width="100%" height="100%" clip-path="url(#heart)" />
<rect x="0" y="50%" fill="red" width="100%" height="100%" clip-path="url(#heart)" />
</svg>