overhang detection

[tmpvar]

Issues like this arise, and can be dangerous in a milling context. Ideally, overhangs would be ignored in this context. The issue is finding a performant way to test what is an overhang vs what is not.

Potential solution: raytrace from "suspect" verts up to the stock.max.z. Count the number of intersections, if > 0 this vert is contributing to an overhung feature.

Once we have collected all of the invalid verts, then we need to safely remove them from the clipping process.

Potential solutions:

• remove and re-mesh (e.g. delaunay)
• store the line start/end when intersecting with a plane, compare these results to the known "bad" verts and ignore if present

where the geometry looks like:

[tmpvar]

this refs tmpvar/mesh-slice-polygon#1