Michael,
Yes that's the right thing!
I'm looking for alternatives to smooth shading since that tells a story about the relationship between the object and some light sources, and I want to focus on the shape of the object primarily. Think about smooth shading on a parabolic reflector: pretty darn hard to tell what shape the reflector is, even with the object in your hands. For smooth shading, I've used Blender with either Freestyle or the new Line Art Modifier for Grease Pencil to generate basic vector line art from the same view as raster shading.
I see a version of your method saving me hours to days per drawing and giving a more convincing result than is feasible with existing tools.
I would be interested in:
1. smooth continuous lines
2. no loops (false lemon umbilics?). I know you like them, and understand the aesthetic value, but they'd make life hard for me when I'm going for minimalism. I'd rather have control over style, such as by sketching over a clean reference or by applying a pattern brush to clean paths.
3. ability to select which line of curvature I'm going to show. In some cases I'd be interested in cross hatching with 2 lines of curvature through every point, as in the examples you've shown, but in many cases I'd rather show the lines that are going in 1 general direction only as in the pdf I attached before. I'm not sure how well defined the problem is of classifying the lines into disjoint sets. Something that pops into my mind is the relative magnitude of curvature of the lines of curvature passing through a point, but I'm not sure that's right.
The last point brings me to something I noticed in a couple old forum threads: requests for closed paths in Ai exports. I suspect that there's a well-defined solution for drawing closed paths around patches of a 2D projected image and that this would be of particular benefit in the case of hatching. Maybe you've already though of this or even discussed it here. If not, I'll make some drawings showing the algorithm when I return from travel.
- Peer |