Changelog

0.1.0 (draft), 2026-10-11

First public draft.

• Format: six orientations on a grid measured in plank thicknesses, steps as fenced blocks, frontmatter, color, id, repeat/offset, rot, rot-step and pivot.
• Placement order: lines in order, repeated lines interleaved by round, plank numbers derived from that order.
• Validation codes, checked at the moment each plank is placed.
• Guides: ruler planks that show and check the gaps of a step.
• Balance check (src/physics.js, --physics): rigid-block equilibrium with friction, after every placement, and a tilting-table margin per step. Solved with HiGHS (optional dependency).
• Drop test (src/drop.js, player, plankmd drop): a Rapier simulation of the model, either dropped at once or replayed plank by plank in building order (replay: true, "Replay build" in the player).
• Reference cases (test/cases/) shared by every balance checker.
• Player and gallery in English and French (player/i18n.js): ?lang=, the stored choice or the browser's languages, and an EN/FR switch. In French, diagnostics are explained from their codes; the validator stays in English.
• Balance check: when the construction falls, the planks reported are where it gives way, preferring the lowest ones, not the plank just placed.
• Drop test: a plank that moves a little and stops has settled, not fallen (tall leaning stacks sag a few degrees in the engine).
• Samples that fall on purpose: a diving board and a leaning tower.
• Player: the balance check is off by default ("Check balance"), runs in a Web Worker even from a page opened from the disk, and shows its progress.
• Balance check: about ten times faster. The linear programs grow one plank at a time and re-solve from the previous solution instead of being rebuilt, tilts first check the sliding limit, and results stream in two passes: the verdict for every placement first (under a second for 200 planks), then the tilt of each step. Plank geometry and materials are shared: loading a 200-plank model takes about 20 ms instead of 200.
• Player: ordinary planks are drawn in bulk (one instanced mesh per size and colour, all edges in one line set): 1152 planks take 6 draw calls instead of 2019. The scene is only rendered when something changes.
• Gallery: eleven larger models (gallery/), up to Notre-Dame de Paris (1392 planks, 29 steps), a gallery page in the player (player/gallery.html), and npm run check:gallery.
• Python reference check with compas_cra (python/), validated on the same cases.
• Samples: the spiral staircase, which could not stand, is replaced by a twisted tower; the corbel bridge steps half a width per layer instead of a full width, which made each pier tip into the gap.
• Reference implementation (src/plankmd.js), CLI validator, 3D player, samples and LLM instructions.