A Topological Picture Book, Rendered

The pipeline renders contour, boundary, and double-curve chains as tapered ribbons, varying pen weight toward the viewer and shadow side. Hidden lines appear dashed on the GPU, and a one-sided paper halo removes lines behind near contours. Hatching follows principal-curvature streamlines at three densities, with tone selecting inked families; highlights stay uninked, and strokes overshoot ends to mimic sketchy lines.