Signpost

A showcase piece, not an example. Procedural timber fingerboard signpost (square post, pyramidal cap from the post half plus overhang, three axis-aligned painted boards lettered with their destinations, with wedges cut from the board section, iron shoe collar and U-wrap straps) then the shipped pipeline: unique-cell UVs, Cycles high-to-low normal bake, LOD chain, convex collider, Unity glTF export.

Boards are yaw 0. Finger tips are wedges whose base is the board's own thickness×height, bitten into the board so the base face is inside it. The cap is added after the post bevel. The post stays on the origin. Hygiene family 15–19: --stray-vert, --lift-z / --short-shoe, --gap-board, --float-strap, --yaw-boards.

It asserts budget conformance of the generated result. It does not witness an API contract. "It rendered without error" is not a check.

Composes skills mesh-editing-and-bmesh, bake-high-to-low, depsgraph-and-evaluated-data, engine-export-presets, and snippets bake_normal_high_to_low.py, setup_bake_target_image.py, lod_chain.py / decimate_to_budget.py, convex_hull_collider.py, export_preset_unity.py (helpers copied, not imported as a package). Hygiene combinatorics match examples/mesh-hygiene-audit (copied, not imported).

Intended size: 1.48 m post, boards 0.62 m, 0.54 m and 0.46 m, 0.118 m post stock; outer AABB 1.260 × 0.142 × 1.551 m.

Budgets#

Declared as named constants; every gate recomputes from the mesh, materials, UVs, evaluated LOD, collider, or export file.

Base triangles dropped from 504 to 376 in the quality pass: glued diamond cubes and a solid shoe block became wedges and a four-plate collar. Outer AABB tightened from 1.368 × 0.201 × 1.566 m.

DECIMATE COLLAPSE triangle counts are not identical across series — 5.2.1 is leaner on LOD1 and LOD2. The gate is a ratio band, not an exact count. Bake pixels are stochastic; the gate is has_data plus operator FINISHED, not byte-identity. Construction is closed-form; the only RNG is the seeded per-piece wood tone. Bevel inputs are sorted by edge index, so the face order is the same on every run. Export byte counts differ on 5.2.1 (glTF serializer), not a gated axis.

Surface and stage#

The quality pass found no geometric defect: the boards, straps, bands and shoe seat as their budgets say. The defects were surface. The finger boards were flat pale yellow; they are now cream paint worn through to the wood by a noise mask, a shade apart per board. The iron read as chrome (metallic 1.0, roughness 0.38) and is now rusted. The post has its own tone and grain. The stage grid grew from 14 to 60 m, because the wall's left edge showed in the corner of the hero. The temp .glb is removed after its size is measured. With no new geometric defect, there is no new budget.

The second pass added a third finger (FORD, 0.46 m, pointing back the way of the first, below the other two) so the post reads as a crossroads, and painted each board's destination and distance on its front face. The lettering is surface: a 5×7 bitmap font painted into a small image covering the boards in object space, cubic-filtered and thresholded so the pixel glyphs round into brush strokes, masked to the front (−Y) faces and worn through with the paint. The third board moved the budgets it should: base triangles 376 → 432 (inside the declared 320–480), metal faces 108 → 126 for its collar, board faces 22 → 33, collider 52 → 56 tris, and boards in the joint audit 2 → 3. The outer AABB is unchanged: the new board is shorter than both the others and sits between existing bands. Every falsifier still exits its code.

Hygiene#

Recomputed from the generated mesh, not asserted about the script.

Joint fit and orthogonal boards#

Falsifiers#

Each violates one named budget. All were run on 4.5.11, 5.1.2 and 5.2.1 and returned the same code on each; after the second pass they were re-run on 4.5.11 and 5.2.1 and still do.

--short-shoe lifts only the iron shoe plates. After zmin snap the post is the AABB zmin, so the AABB gate would still pass; the named shoe stations fail. --gap-board moves the board inner station outside the post. --float-strap adds Y offset to the U-wrap so it no longer bites. --yaw-boards restores a 0.12 rad yaw; the AABB secondary extent exceeds the thickness bound.

Run#

blender --background --python signpost.py --
blender --background --python signpost.py -- --skip-decimate
blender --background --python signpost.py -- --stray-vert
blender --background --python signpost.py -- --lift-z
blender --background --python signpost.py -- --short-shoe
blender --background --python signpost.py -- --gap-board
blender --background --python signpost.py -- --float-strap
blender --background --python signpost.py -- --yaw-boards
blender --background --python signpost.py -- --output signpost.png

Smoke passes no flags.

Exit codes#

File-local. 9 is a valid check code. 10 is reserved for gallery_framing.check_framing on the --output path. 15–19 are the hygiene and joint-fit family.