| It works in the case of a cube if you define the cube to be the intersection of 6 half-spaces. There is a video demonstration of it working (partly) on a cube defined this way in the YouTube link in my comment above. I define a surface to be the region of space where a particular SDF evaluates to 0. You define a solid to be the region of space where that SDF evaluates to <0, but they're broadly the same concept. It is no problem to ensure that all primitives & all extruded sketches are defined so that each face gets a different surface id, and you would of course want to do this if you want to be able to fillet them. You're right that there is a difference between an edge and between a pair of surfaces, but finding edges in SDFs is much harder than finding pairs of surfaces. If they intersect along more than one edge then you'll get the fillet along more than one edge. SDFs don't even have concrete "edges" in the general case. I'm not worried about this. Being able to fillet the intersection of 2 surfaces (solids) would satisfy me, but I haven't even got that far. I'm not trying to find a solution that involves treating edges as "special". That's B-rep thinking. I don't mind if a "fillet" between 2 surfaces that do not touch but are closer together than the fillet radius creates a bridge between them, as long as it is smooth, continuous, and predictable. It doesn't have to approximate the B-rep way, it just needs to be practically useful for turning sharp edges into rounded ones in a way that lets the user decide where. |