minkowski2d
The boolean operator <minkowski2d> specifies the 2d minkowski sum of exactly two 2d shapes. No 3d objects may occur in this context. The result is a new 2d shape. In this implementation, the order of the parameters matter. The first parameter is generally the larger and can be concave or convex. The second parameter is assumed smaller and convex (such as a circle). Typical use of the minkowski sum is to create an object with rounded corners.
To understand the minkowski sum, one may consider it to be the first object plus the second object placed in every position along the edges of the first object.
Example with the minkowski sum of a rectangle and a circle, extruded to create a 3d solid.
<?xml version="1.0" encoding="utf-8"?>
<xcsg version="1.0">
<linear_extrude dz="1">
<minkowski2d>
<rectangle dx="200" dy="100" center="true"/>
<circle r="20"/>
</minkowski2d>
</linear_extrude>
</xcsg>