""" Path-following scroll unroll: the spiral lays down ALONG its arm, led by a 3D curl. The shell's `growth` parameter truncates the spiral along its own arm (not radially), so a sequence of growth stages IS a scroll unrolling along the spiral path: an outer ring stays hidden until the arm reaches it, even if an inner point at the same clock-angle is already laid down. We render N growth stages as a flipbook stacked in one SVG. Each stage is shown in sequence via SMIL (set/animate on opacity), so the laid parchment grows along the arm. A 3D curl object (a small cylinder with a gold highlight and a cast shadow) rides the leading tip via animateMotion along the centerline path, shrinking as it spends its paper, then vanishes at the rim. This is heavier than a single-SVG animation (~1.6MB for 14 stages) but it is the only way to get a genuine path-following reveal of a filled spiral. """ from __future__ import annotations import math import re N_STAGES = 14 UNROLL_DUR = 3.6 # total seconds EYE_X, EYE_Y = 320.0, 335.0 def _centerline_d(svg: str) -> str | None: m = re.search(r' str: """A 3D paper-curl cylinder, sized for how much paper remains (shrinks as the scroll unrolls). Returned as a to be motion-animated.""" # remaining paper ~ (1 - stage_frac); curl radius shrinks from ~16 to ~5 r = 5 + 11 * (1 - stage_frac) return ( f'' # cast shadow on the parchment just behind the curl f'' # the cylinder body (the rolled paper, seen end-on) f'' # inner roll rings (paper thickness) f'' f'' # gold highlight on the rounded leading edge f'' f'' ) def build_unroll_doc(stage_svgs: list[str]) -> str: """Stack growth-stage SVGs as a flipbook + a curl riding the tip. Returns one SVG string with SMIL timing. stage_svgs[i] is the shell at growth (i+1)/N. Each stage is wrapped in a that becomes visible at its time slot and hides when the next appears, so the laid parchment advances along the arm. The final stage stays visible (freeze). """ n = len(stage_svgs) slot = UNROLL_DUR / n # strip the outer