fill2d
The boolean operator <fill2d> fills any internal holes in a 2d shape. The result is a new 2d shape. It works similar to hull2d, but where hull2d leaves a convex shape as a result, fill2d leaves the original outer contour untouched, even if it is concave.
The following example first shows creation of a 2d shape with holes, extruded to create a 3d solid. Scroll down to see the same shape processed with fill2d.
<?xml version="1.0" encoding="utf-8"?>
<xcsg version="1.0">
<metadata>
<software name="angelcad" version="v1.0-01"/>
<model name="fill2d" created="2017-09-11T17:36:44"/>
</metadata>
<linear_extrude dz="1">
<difference2d>
<union2d>
<polygon>
<vertices>
<vertex x="0" y="0"/>
<vertex x="100" y="0"/>
<vertex x="50" y="100"/>
</vertices>
</polygon>
<square size="80" center="false"/>
</union2d>
<union2d>
<polygon>
<vertices>
<vertex x="40" y="20"/>
<vertex x="80" y="20"/>
<vertex x="70" y="50"/>
</vertices>
</polygon>
<circle r="40"/>
<circle r="10">
<tmatrix>
<trow c0="1" c1="0" c2="0" c3="30"/>
<trow c0="0" c1="1" c2="0" c3="50"/>
<trow c0="0" c1="0" c2="1" c3="0"/>
<trow c0="0" c1="0" c2="0" c3="1"/>
</tmatrix>
</circle>
</union2d>
</difference2d>
</linear_extrude>
</xcsg>Concave shape with internal holes:
Now apply the <fill2d> operator to the above 2d shape, before extruding:
<?xml version="1.0" encoding="utf-8"?>
<xcsg version="1.0">
<metadata>
<software name="angelcad" version="v1.0-01"/>
<model name="fill2d" created="2017-09-11T17:39:46"/>
</metadata>
<linear_extrude dz="1">
<fill2d>
<difference2d>
<union2d>
<polygon>
<vertices>
<vertex x="0" y="0"/>
<vertex x="100" y="0"/>
<vertex x="50" y="100"/>
</vertices>
</polygon>
<square size="80" center="false"/>
</union2d>
<union2d>
<polygon>
<vertices>
<vertex x="40" y="20"/>
<vertex x="80" y="20"/>
<vertex x="70" y="50"/>
</vertices>
</polygon>
<circle r="40"/>
<circle r="10">
<tmatrix>
<trow c0="1" c1="0" c2="0" c3="30"/>
<trow c0="0" c1="1" c2="0" c3="50"/>
<trow c0="0" c1="0" c2="1" c3="0"/>
<trow c0="0" c1="0" c2="0" c3="1"/>
</tmatrix>
</circle>
</union2d>
</difference2d>
</fill2d>
</linear_extrude>
</xcsg>Concave shape with internal holes filled:
