Together with another Anders (from Sweden) I've worked a little bit on some C# code for rendering stuff in OpenGL. The idea is to put together a basic framework where CAD/CAM ideas and algorithms can be tested. Above one of the first useful screenshots where I've rendered an STL file with about 22k triangles.

The code needs to be cleaned up and made all object-oriented and nice, but after that it should not be hard to test the Drop-Cutter algorithm and generate some raster-finish paths.

I've also been reading a 2004 paper by Yau et al. which explains the drop-cutter algorithm for an APT tool. I'm not very interested in the tapered cutters - but that can be added later if needed. What's more interesting in the paper is a kd-tree approach for finding out which triangles are under the 'shadow' of the cutter.

The idea is that it's not necessary to test against all triangles, only those that are under the cutter. Since the circular cutter and the triangles are differently shaped, Yau et al. start by approximating both cutter and triangles with rectangles. So they generate rectangular bounding boxes around each triangle and also around the cutter. The task then is for a given position of the cutter to find which bounding-boxes(triangles) intersect it. I understand this is a variant of what's called an orthogonal range search in computer science.

If anyone with a good understanding of kd-trees and/or range-searching is willing to help with a C# implementation I'd be glad to send over the Yau et al. pdf!