Iron Cauldron

A showcase piece, not an example. Procedural hanging cauldron (a round-bellied cast-iron pot with a rolled rim, a raised casting band at the belly and three stub feet, a pipe bail threaded through flat ear rings and hung by a five-link chain, a timber tripod seated in a forged iron head, iron ferrule cups coaxial with the poles) then the shipped pipeline: unique-cell UVs, Cycles high-to-low normal bake, LOD chain, convex collider, Unity glTF export.

Ferrules are lofted along the pole axis and shifted so the downhill rim sits at Z=0. A world-Z bucket lets a leaning pole slice the lip. ferrule_bite is measured in that same frame, and only samples wood inside the cup's own axis span — a pole hovering above the well cannot fake a seat.

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).

Budgets#

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

Base triangles rose from 3388 to 3664 in the quality pass: coaxial ferrule cups and a dual-wall lathe with a rolled rim replaced the old cone-tripod / overlapping-torus construction. The #345 remodel (the asset sheet read it as the least-designed object in the lineup) took it to 4180: a five-link chain replaced the bare hanging rod, a forged iron head replaced the turned wooden crown, and the pot gained a casting band and three stub feet. The iron material breaks its rust into blotches and adds fine sand-cast pitting. 4180 leaves 20 triangles under the ceiling, enough for --short-legs's 12-triangle shim to still land on the support check (16), not the triangle budget (4).

Hygiene#

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

Joint fit and seat#

DECIMATE COLLAPSE triangle counts are not identical across series — 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-pole wood tone. Export byte counts differ on 5.2.1 (glTF serializer), not a gated axis.

Pot, ears and surface#

The pot was a quadratic profile from a 28 mm tip: an onion that ran to a point. It is now a superellipse belly from a 75 mm flat base out to 0.180 m at 0.42 of the height, then a rounded shoulder in to a 0.128 m mouth. The inner wall is offset along the profile's normal, not sideways, so it keeps its thickness where the wall runs nearly flat. Pot form asserts it; --pointed-pot restores the old profile (base 0.028 m, widest at 0.727 of the height) and exits 19.

The ear rings stood in the bail's own XZ plane, so the bail ran through the ring's tube rather than its hole, and its ends hung into the pot's mouth. The rings now lie flat, bite 2 mm into the rim's outer edge, and the bail (vertical where it passes) threads them. Past each ear the bail is mirrored about the ring, so its ends hook outward. Bail through the ears asserts it; --edge-on-ears restores the old rings (36 ring vertices inside the bail) and exits 17.

Cast iron is near-black and rough with rust in the pores; each pole has its own tone and grain along its axis. The temp .glb is removed after its size is measured.

Falsifiers#

Each violates one named budget. All nine were run on 4.5.11, 5.1.2 and 5.2.1 and returned the same code on each.

Run#

blender --background --python iron_cauldron.py --
blender --background --python iron_cauldron.py -- --skip-decimate
blender --background --python iron_cauldron.py -- --stray-vert
blender --background --python iron_cauldron.py -- --lift-z
blender --background --python iron_cauldron.py -- --short-legs
blender --background --python iron_cauldron.py -- --float-hook
blender --background --python iron_cauldron.py -- --pipe-ferrule
blender --background --python iron_cauldron.py -- --pointed-pot
blender --background --python iron_cauldron.py -- --edge-on-ears
blender --background --python iron_cauldron.py -- --output cauldron.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.