Watchtower

A showcase piece, not an example. Procedural timber lookout (corner posts through a plank platform, lower-bay X-braces, hatch and ladder whose stiles plant at Z=0, coursed shake roof over a solid cone, mitered iron collars and shoes) then the shipped pipeline: unique-cell UVs, Cycles high-to-low normal bake, LOD chain, convex collider, Unity glTF export.

The first quality pass left the platform floating: there were no bearers at deck level, the two joists stopped 0.19 m short of the front edge and at the back edge in the air, the plank ends hung past nothing at the sides, and the side guardrails stopped 0.30 m short of the front posts for a "hatch clearance" the hatch never needed (it sits at the centre of the front edge). Four deck girts now tenon into the posts under the planks, the joists run girt to girt, the hatch trims end on the front girt, and the side rails span post to post like the back rail. Two budgets assert it. Wood carries grain and a tone per piece, the shakes are weathered, and the iron is rusted rather than chrome.

The old roof was a wood U with incomplete shake coverage; rails showed through the eave. The cone plus non-overlapping courses close the pyramid. Shoes are added after the zmin snap so a bevel undershoot cannot lift them.

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 5220 to 6408 in the first quality pass (a taller eave-true roof and coursed shakes) and to 6840 in the second (four deck girts), not hidden interior faces.

Hygiene#

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

Joint fit and seat#

DECIMATE COLLAPSE triangle counts are not identical across series — 5.2.1 is leaner on 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 uses no RNG; the per-piece wood tone is drawn from a seeded random.Random(TONE_SEED), the same every run. Export byte counts differ by 16 B on 5.2.1 (glTF serializer), not a gated axis.

Falsifiers#

Each violates one named budget. Every falsifier was run on 4.5.11, 5.1.2 and 5.2.1 and returned the same code on each.

Run#

blender --background --python watchtower.py --
blender --background --python watchtower.py -- --skip-decimate
blender --background --python watchtower.py -- --stray-vert
blender --background --python watchtower.py -- --lift-z
blender --background --python watchtower.py -- --short-shoes
blender --background --python watchtower.py -- --short-rails
blender --background --python watchtower.py -- --open-sides
blender --background --python watchtower.py -- --short-joists
blender --background --python watchtower.py -- --float-band
blender --background --python watchtower.py -- --rake-posts
blender --background --python watchtower.py -- --output tower.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.

Hero#

The still used to tilt the tower 2° about X, which the showcase rule "level on the stage" forbids (it sinks one row of shoes and lifts the other); it now turns about Z only. The camera moved in and down (fill y 0.856, was ~0.77) so the tower reads as tall rather than lost in the frame, and the shake roof went from flat grey to weathered cedar brown with silvered wear. Geometry and budgets are unchanged.