Modeling botanical fiber topologies for Japanese washi

The capillary mechanics of fluid change drastically depending on the paper's microscopic fiber skeleton. I expanded the parchment_gen.wgsl shader to 141 lines to procedurally generate three distinct traditional substrates: Kizuki Kōzo (unbleached mulberry), Torinoko (sized eggshell), and Kobishi (vintage tea-tannin). By tracking physical tangents along the sinuous bast fibers, the fluid dynamics solver now knows exactly where to pool and where to bleed aggressively, matching the distinct behaviors of each paper type.