Hole Detection #10

I'm looking at using your lib to modify 2d texture maps on 3d meshes based on where the meshes are pressed against each other (anti-coplanar faces.) After performing an operation which returns a polygon with multiple Regions, is there a way to know if the Regions refer to holes vs freestanding polygons? In the example below, when subtracting blue from red, both scenarios return 3 Regions. From my experimenting, it appears that the first Region returned tends to be "the biggest outermost Region", but the remainder being holes or not is unclear. I tried testing to see if the vertex winding order is opposite for outlines / holes, but it did not seem to be. I've read through tutorials on this algorithm, and have a vague sense that the notion of "a RegionIS a hole or not" might itself be loosely defined.

Ultimately, I really just need to be able to take the regions that pop out of an intersection operation, and apply an earcut / tessellating algorithm to them to get a triangularized mesh. The only earcut implementations I've found specifically ask for information on where the holes are; do you know of any implementations which would work using the output of your lib?