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Blender Developer Tools

Skills, rules, snippets, templates, and runnable examples for Blender Python development

Release License

Validate Blender smoke tests Drift check

16 skills  •  9 rules  •  3 templates  •  27 snippets  •  60 examples  •  66 showcase pieces

Examples Gallery  •  Quick start  •  Examples  •  Showcase  •  Skills  •  Rules  •  Templates  •  Snippets  •  Roadmap

Overview

This repository ships 16 skills, 9 rules, 3 templates, 27 snippets, 60 examples, and 66 showcase pieces for Blender Python development targeting Blender 5.2 LTS (current stable) with Blender 4.5 LTS fallback support. Blender 5.1 is prior stable.

The content is consumed by AI coding agents reading these files directly from a checkout — there is no MCP server in this repository, and none is required. Cursor applies rules/*.mdc automatically wherever their scope globs match and takes skills by name in chat; Claude Code reads skills/ and rules/ from the project workspace, or from this repo kept as a referenced checkout. Any agent that can read files in a workspace can use it the same way. There is no build step for the content — edit the Markdown and Python files directly.

Layer Role
Skills Guided workflows: scaffolding, operators, panels, properties, mesh and bmesh, headless batch, slotted actions, geometry nodes, procedural materials, depsgraph queries, drivers and handlers, bl_info migration, video sequencer, imported-mesh cleanup, engine export presets
Rules Guardrails for the most common AI mistakes: ops-in-loops, bmesh leaks, legacy bl_info only, prop assignments, deprecated context-copy override, per-element loops over bulk mesh data, import without scale check, export without evaluated geometry, mixed glTF/FBX axis RNA
Templates A working Extensions Platform add-on starter, a headless batch script starter, and a GLB-in engine-ready asset pipeline
Snippets 27 small standalone Python files demonstrating canonical patterns
Examples Runnable headless scripts under examples/. Each asserts an API contract and exits non-zero on failure.
Showcase Budget-conformance props under showcase/. Not examples. Conventions: showcase/README.md

Quick start

git clone https://github.com/TMHSDigital/Blender-Developer-Tools.git
  • Cursor — point Cursor at the checkout (or symlink rules/ into your project). The .mdc rules apply automatically by glob scope; skills are referenced by name in chat.
  • Claude Code — copy skills/ and rules/ into your project workspace, or keep this repo as a checkout that Claude Code references directly.
  • Get Blender — download 5.2 LTS (primary target) or 4.5 LTS (supported fallback) from blender.org/download/lts; current stable lives at blender.org/download. The blender command below is that binary — on macOS it is inside the app bundle at /Applications/Blender.app/Contents/MacOS/Blender.
  • Run an example — every example is a self-checking headless script (exit non-zero on failure, no GPU needed for the check):
blender --background --python examples/bmesh-gear/bmesh_gear.py --

Supported Blender versions

Version Status
Blender 5.2 LTS Primary target (current stable; all examples assume 5.2 unless a 4.5 path is shown)
Blender 5.1 Prior stable (weekly cron; PR via needs-5.1 or manual dispatch)
Blender 4.5 LTS Fallback supported (skills show both code paths where 4.x and 5.x APIs diverge)

Falsifiers

Every one of the 60 examples carries a falsifier: a flag that changes the input so a real assertion fails. It never disables the assertion, skips the check, or short-circuits to an error — it feeds the script something the contract says must not pass, and the same check that guards the happy path catches it.

# The contract holds: exit 0
blender --background --python examples/bmesh-gear/bmesh_gear.py --

# The falsifier: skip the extrude, so the topology no longer matches the
# closed form. The topology check fires and the script exits 3.
blender --background --python examples/bmesh-gear/bmesh_gear.py -- --no-extrude

This is what makes a green run mean something. An assertion that has only ever passed witnesses nothing — it could be comparing a constant to itself. Proving each one fails once, on demand, is the difference between a test suite and a set of scripts that print "OK". Shipping an example requires demonstrating the falsifier's non-zero exit and reporting the measured error.

--api, --check-pixels, and --output are not falsifiers; they select a code path rather than break a contract. Full conventions, including the per-script exit-code model, are in CONTRIBUTING.md.

Showcase

Budget-conformance props. Not examples. Conventions: showcase/README.md.

66 showcase pieces — click to expand the preview grid

Shipping crate: a wooden slat crate stencilled PORT ROYAL and NO 17, with iron corner brackets and an end handle, on a dark studio floor, warm wedge on the back wall Stone well: a round well of varied grey stones with a grained wooden pyramid roof on posts, rope and a bucket on rusted iron hoops, on a dark studio floor Wooden barrel: a 20-stave wine-cask with a head of four boards, chord-lofted iron hoops, and a bung on a dark studio floor Campfire: a two-course ring of warm, soot-dark fieldstones around a tripod of charring logs over ember-cracked coals on a dark studio floor, warm wedge on the back wall Market stall: a grained timber frame with post feet, diagonal side braces, slatted counter, rafters, and a striped canvas awning on a dark studio floor, warm wedge on the back wall Street lantern: a cast-iron lamp post with a fluted column, brass collars, a ladder bar and a scrolled, braced arm, its banded lantern lit amber from inside Treasure chest: a slatted wooden chest with iron bands, corner brackets, and an open lid on a dark studio floor Terrain scatter: a Geometry Nodes hill tile of patchy grass over dark earth, nine faceted stones sunk into it among grass tufts and pebbles, on a dark studio floor Fence kit: a run of three weathered post-and-rail sections on a packed-earth strip sharing one post at each joint, with pyramidal caps, diagonal board braces, and iron bands Watchtower: a grained timber lookout seen from low and close, with X-braces, hatch ladder, a plank platform on deck girts, and a weathered cedar shake roof on a dark studio floor Cart: a two-wheel wooden cart with spoked wheels, slatted bed, and shafts on a dark studio floor Park bench: a wrought-iron bench whose round-bar legs curl into scrolled feet, with wooden slats and a reclined back, on a dark studio floor Wheelbarrow: a wooden tray with walls of stacked boards and iron straps, a spoked wheel, rear legs, and handles on a dark studio floor Anvil: a forged-steel London-pattern anvil with a hammer-polished face on a hooped timber stump, a hammer at its foot Water trough: a staved wooden trough on pegged trestle legs, iron straps bolted and clipped over the rim, rippled water inside and a bung in one end Hitching post: a square timber post with a pyramidal cap, a cross-arm on two knee braces with iron end caps, iron bands wrapped around it, two hitching rings and a nailed horseshoe on a dark studio floor Grindstone: a sandstone wheel dipping into a water-filled trough on a timber A-frame, with iron axle, hubs and a crank turned toward the viewer, on a dark studio floor Hand pump: a green-enamelled cast-iron village pump with a fluted barrel, ball finial and counterweighted handle on a stepped wooden plinth, a hooped wooden bucket under its spout Signpost: a timber crossroads post with three painted fingerboards lettered MILLBROOK 2, OAKHAM 5 and FORD 1, iron straps, and a pyramidal cap on a dark studio floor Chopping block: a bark-sided log round with growth rings and drying checks on its sawn top, a riveted iron hoop, a felling axe buried in the top, and split billets and chips at its foot, on a dark studio floor Wooden bucket: a coopered pail with a three-strand rope bail through iron ear rings and chord-lofted iron hoops on a dark studio floor Wall torch: a dressed stone plaque with an iron plate and arm holding a cup, a leaning wooden torch with a pitch-wrapped head and a bright flame, on a dark studio floor Tavern stool: a dished round wooden seat holding a pewter tankard, on turned splayed legs with stretchers at two heights and iron ferrules on flat treads, on a dark studio floor Iron cauldron: a round-bellied cast-iron pot hanging by its bail from a timber tripod on a dark studio floor Wooden ladder: an oak ladder with six pale turned hickory rungs through-tenoned into its rails, iron tie-rods under the end rungs and iron shoes, leaning on a barn-board wall with a rope coil on a rung Hay bale: a bound straw bale with two sisal twine belts on a dark studio floor Crate stack: three slatted shipping crates stacked and yawed, each with iron corner straps and runners, on a dark studio floor Stone archway: a semicircular masonry arch with coursed piers, projecting imposts, nine voussoirs and a proud keystone, on a dark studio floor Rope bridge: a sagging plank deck on foot ropes between two pairs of log posts, with lashed hemp hand ropes, suspenders, and ropes staked to the ground, on a dark studio floor Grain sacks: three burlap sacks gathered and tied with twine, two standing and one lying slumped in front, one blue-striped and one red-striped, on a dark studio floor Brazier: an iron fire bowl with a rolled rim on three S-curved forged legs, holding ash and a heap of glowing charcoal, on a dark studio floor Apothecary shelf: a stained wooden shelf unit with an arched crest, gallery rails and three drawers, stocked with labelled glass bottles, flasks and glazed jars, on a dark studio floor Wooden yoke: a carved oak ox yoke with upturned ends standing on two bent hickory oxbows pinned above the beam, with an iron ring hung under its centre, on a dark studio floor Butter churn: a tall staved oak churn narrowing toward the top, bound by three iron hoops, with a two-board lid and a maple dasher handle rising through it, on a dark studio floor Bookshelf: a stained wooden bookcase of cloth and leather hardbacks, some standing, some stacked flat and two leaning on their neighbours, on a dark studio floor Book trolley: a double-sided wooden library book truck on four casters, two sloped troughs of hardbacks leaning back spines out and loose books stacked on its deck, on a dark studio floor Basketball hoop: an in-ground goal with a padded square gooseneck pole, a framed backboard with a red shooter's square, an orange rim and a white net, standing on a concrete court pad with a faded green key, free-throw circle and three-point arc, two basketballs on the concrete Pine tree: a mature Scots pine with a tall bare bole, dead lower limbs and a broad, rounded crown of soft blue-green needle brushes over red limbs, on a small disc of needle-litter soil with mossy stones, on a dark studio floor Desk lamp: a red balanced-arm lamp with a stepped base, parallel-rod arms, chrome springs and knurled knobs, and a domed shade glowing around its bulb, on a dark studio floor Quad drone: a white-and-graphite camera quadcopter on four carbon arms with red lock rings, twin-blade props, rubber-footed skids and a three-axis gimbal camera, on a dark studio floor Soccer goal: a white 5 by 2 m youth goal with sloped rear supports and a sagging diamond-mesh net edged in red rope, on a turf patch with a painted goal line, on a dark studio floor Fallen log: a mossy log settled into a soil mound, its dark furrowed bark peeled in patches, a hollow ringed butt, tiers of shelf fungi, toadstools, ferns and fallen leaves, on a dark studio floor Office chair: a graphite mesh-back task chair with a muted-teal two-tone seat, a mesh headrest and 4D armrests on a polished five-star base, standing on a smoked chair mat beside a snake plant in a stone planter Hover bike: a muted-teal sci-fi speeder with pearl racing stripes, panelled flanks, a stitched black saddle and two ducted fans with orange spinners, standing on pinned landing gear with orange shock absorbers and teal skis, on a dark studio floor Weight rack: a red half rack holding a barbell loaded with blue and yellow bumpers on J-hooks, plates on storage horns and two hex dumbbells, on a dark studio floor Boulder cluster: a speckled granite block, a banded sandstone boulder split in two and a slab resting on a smaller boulder, sunk in a grassy soil mound with pebbles and wildflowers, on a dark studio floor Floor fan: a sage-green 1950s pedestal fan with a chrome wire guard over four brass blades, its head turned on a tilt yoke, a telescoping column and a round cast base, its cord looped to a plug, on a dark studio floor Motor scooter: a pastel sea-green 1960s step-through scooter with a two-tone cream and oxblood dual saddle, louvred side cowls, a curved chrome-trimmed leg shield, split-rim wheels and a black silencer, on its centre stand on a dark studio floor Bowling pins: ten white pins with red neck stripes racked on a dark pin deck at the end of a glossy maple lane with arrows and dots, a marbled violet ball on the approach, between gutters and kickbacks, on a dark studio floor Pond edge: a dark rippled pond on a raised soil disc, cattails with brown seed heads and rush tufts on the far bank, notched lily pads and two pink-white water lilies, wet stones and a branch at the waterline, on a dark studio floor Stand mixer: a slate-blue retro tilt-head stand mixer with a chrome trim band and a brushed steel bowl on a stone countertop, beside a wire whisk, a steel measuring cup and two brown eggs in a terracotta dish, on a dark studio floor Cargo loader: a yellow bipedal powered-lift exoframe in a crouch, hydraulic rams and pinned clevises on its legs and arms, an open roll-cage cockpit with a seat, harness and amber beacon, a power pack behind, holding a corrugated blue-grey crate on two forks, on a dark studio floor Archery target: a straw boss with a gold, red, blue, black and white face and five arrows, leaning on a timber easel numbered 12 with a hinged rear leg and a splay chain, on a turf patch with a leather quiver and a snapped arrow in the grass, on a dark studio floor Cactus garden: a ribbed, many-armed saguaro, rows of spines and cream flowers on its crown, a barrel cactus with red hooked spines and yellow fruit, a prickly pear with magenta fruit, an agave rosette and sandstone rocks on a raised sand disc, on a dark studio floor Espresso machine: a brushed stainless E61 espresso machine with twin gauges, a chrome group head and a walnut-handled portafilter over a shot cup, cups on its warmer tray, beside a tamper, milk pitcher and knock box on a stone counter Road bicycle: a deep red lugged-steel road bicycle leaning on its kickstand, with chromed lugs and fork socks, tan-wall 700c wheels, a honey leather saddle, cream-taped drop bars and a chain over a double crankset Skate ramp: a plywood quarter-pipe with a steel coping and kicker plate, screw rows, sheet seams and a red stencilled roundel, its open side showing studs and sills, a skateboard on the deck Palm tree: a coconut palm leaning on a raised disc of beach sand, its ringed trunk curving up to a crown of drooping pinnate fronds over green coconuts, fallen coconuts, a frond and driftwood below Wingback armchair: an oxblood leather wingback with a deep-button tufted back, rolled arms trimmed with brass nailheads and a piped seat cushion, beside a side table with a brass reading lamp and books on a fringed rug Planet rover: a six-wheeled rocker-bogie rover with gold-foil sides, a camera mast, a dish antenna and a finned power unit, its arm drilling a boulder on red-grey regolith Traffic cones: orange cones with white reflective collars on a patch of asphalt with a worn white line, three standing in a row, three nested in a stack and one knocked over showing its open base, before a striped A-frame barricade with an amber warning lamp Mushroom stump: a sawn tree stump with ringed, cracked end grain and torn splinters on a sloping soil disc, buttress roots in the soil, moss, banded shelf fungi, honey mushroom clusters, red fly agarics, ferns and fallen leaves Go-kart: yellow go-kart on a patch of track asphalt before a red and white kerb: bent red tube chassis, black seat, finned engine with chain to the rear axle, slick tyres on silver rims. Broadleaf oak: a broad oak with a short fluted trunk and crooked spreading limbs under a domed crown of lobed green leaves, on a grassy soil disc with surface roots, tufts, fallen leaves and acorns Farm tractor: green farm tractor in muddy ruts beside a puddle: long bonnet, barred grille, rusty exhaust stack, big lugged rear tyres on cream rims with weights, small ribbed fronts. Fern and mossy rock: a male fern's arching crown of finely cut fronds, with curled fiddleheads, in front of a cleft boulder cushioned in moss on a soil bank with fallen beech leaves, pebbles and wood sorrel

shipping-crate — procedural crate through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets. Falsifier --skip-decimate exits 9.

stone-well — procedural round stone well, shingled roof, windlass, rope and bucket through the same pipeline. Falsifier --skip-decimate exits 9.

wooden-barrel — procedural 20-stave wine-cask with boarded, croze-seated heads and chord-lofted hoops through the same pipeline. Falsifiers --round-band exits 18, --one-piece-head exits 17.

campfire — procedural fieldstone ring, logs, and ash through the same pipeline. Falsifiers --skip-decimate exits 9, --uniform-stones exits 20.

market-stall — procedural timber stall with striped awning and counter through the same pipeline. Falsifiers --skip-decimate exits 9, --short-brace exits 17.

street-lantern — procedural hanging lantern with iron post, brass fittings, and amber cage through the same pipeline. Falsifiers --skip-decimate exits 9, --shallow-brace exits 20.

treasure-chest — procedural slatted chest with iron bands, corner brackets, and an open lid through the same pipeline. Falsifier --skip-decimate exits 9.

terrain-scatter — Geometry Nodes hill tile with bevelled masonry scatter through the same pipeline. Falsifier --skip-decimate exits 9.

fence-kit — procedural post-and-rail fence section through the same pipeline. Falsifier --skip-decimate exits 9.

watchtower — procedural timber lookout with X-braces, hatch ladder, platform, and coursed shake roof through the same pipeline. Falsifiers --skip-decimate exits 9, --short-joists exits 17.

cart — procedural two-wheel wooden cart with spoked wheels, slatted bed, and shafts through the same pipeline. Falsifier --skip-decimate exits 9.

park-bench — procedural wrought-iron park bench with scrolled legs and slatted seat through the same pipeline. Falsifier --skip-decimate exits 9.

wheelbarrow — procedural wheelbarrow with board-built tray walls, a spoked wheel, iron straps, legs, and handles through the same pipeline. Falsifiers --skip-decimate exits 9, --wide-seams exits 17.

anvil — procedural London-pattern anvil on a timber stump through the same pipeline. Falsifiers --skip-decimate exits 9, --round-waist exits 19.

water-trough — procedural watertight water trough on a timber stand through the same pipeline. Falsifier --skip-decimate exits 9.

hitching-post — procedural timber hitching post with a cross-arm, wrapped iron bands and iron rings through the same pipeline. Falsifiers --skip-decimate exits 9, --sunk-bands exits 18.

grindstone — procedural grindstone on a timber trestle with iron axle and crank through the same pipeline. Falsifier --skip-decimate exits 9.

hand-pump — procedural cast-iron village hand pump through the same pipeline. Falsifier --skip-decimate exits 9.

signpost — procedural timber fingerboard signpost through the same pipeline. Falsifiers --skip-decimate (9), --stray-vert (15), --yaw-boards (19).

chopping-block — procedural hooped timber stump with an embedded axe through the same pipeline. Falsifier --skip-decimate exits 9.

wooden-bucket — procedural coopered pail with a three-strand rope bail through the ear rings through the same pipeline. Falsifiers --float-handle and --sunk-rope exit 17.

wall-torch — procedural wall-mounted torch sconce with a stone plaque, iron bracket, and flame through the same pipeline. Falsifiers --skip-decimate (9), --stray-vert (15), --float-arm (17).

tavern-stool — procedural tavern stool with turned legs, stretchers, and iron ferrules through the same pipeline. Falsifier --skip-decimate exits 9.

iron-cauldron — procedural round-bellied iron cauldron on a timber tripod through the same pipeline. Falsifiers --skip-decimate exits 9, --pointed-pot exits 19.

wooden-ladder — procedural timber ladder with raked stiles, evenly pitched rungs, and iron shoes through the same pipeline. Falsifiers --skip-decimate exits 9, --drift-rungs exits 19.

hay-bale — procedural bound hay bale with sisal twine through the same pipeline. Falsifier --skip-decimate exits 9.

rope-bridge — procedural rope footbridge whose plank deck is fitted to a parabola recomputed from the plank tops, with lashed hand ropes and staked foot ropes, through the same pipeline. Falsifiers --vee-deck exits 19, --float-suspenders exits 18.

grain-sacks — procedural pile of burlap grain sacks settled onto flat bases and tied with twine, through the same pipeline. Falsifiers --round-bottom exits 19, --slip-tie exits 17.

brazier — procedural iron brazier with ash and glowing charcoal whose tip angle is recomputed from a density-weighted mass centre and the feet on the floor, through the same pipeline. Falsifiers --tuck-legs exits 19, --overfill exits 18.

apothecary-shelf — procedural apothecary shelf stocked with fifteen labelled bottles, flasks and jars, whose headroom under the shelf above is recomputed per vessel, through the same pipeline. Falsifiers --tall-flask exits 20, --short-shelves exits 17.

wooden-yoke — procedural double ox yoke on two bent hickory bows with a hung ring, whose neck openings are measured between the bow legs and up to the saddles, through the same pipeline. Falsifiers --pinch-bows exits 19, --edge-on-ring exits 17.

butter-churn — procedural staved plunge churn whose dasher stroke is recomputed from the inner wall read off the staves and the plunger's reach, through the same pipeline. Falsifiers --wide-dasher exits 20, --tight-hole exits 18.

bookshelf — procedural bookcase of thirty-eight rounded-spine hardbacks, standing, stacked and leaning, whose leaning books' contact with their neighbour's head edge is recomputed as a band, through the same pipeline. Falsifiers --air-lean and --deep-lean exit 22, --crowd-books exits 23.

book-trolley — procedural double-sided library book truck on four casters, forty-seven hardbacks in four sloped troughs, whose every book's fore-edge depth in its backrest is recomputed as a band beside its shelf seat, through the same pipeline. Falsifiers --off-back and --deep-back exit 21, --skew-caster exits 19.

basketball-hoop — the first sports piece: procedural in-ground basketball goal on a patch of driveway court (square gooseneck pole swept in one piece with bend webs, bolted into a two-pour concrete pad, braced board in an aluminium frame, breakaway regulation rim, knotted twelve-loop net, faded court paint, two basketballs), whose rim height over the court, inside diameter, board gap and level, every net loop threaded on its rim hook, each ball resting on its slab, the anchor bolts set through the plate into the slab, and every paint line set into its slab, are recomputed from the mesh, through the same pipeline. Falsifiers --drop-net exits 18, --tilt-rim 19, --loose-pad 20, --float-ball 21, --short-bolts 22, --float-paint 23.

pine-tree — the first nature piece: procedural mature Scots pine on a needle-litter soil disc (a buttressed trunk with plated lower bark bedded in the soil, surface roots, eight seeded whorls of heavy crooked limbs, 113 overlapping brushes of long thin needle strands each on its own twig, dead stubs and limbs, hanging cones, fallen cones, mossy stones and sticks), whose every limb's seat in the bark, whorl spacing, trunk plumb and crown balance, every clump seated on its own carrier and the ground cover bedded in the soil are recomputed from the mesh, through the same pipeline. Falsifiers --float-branches exits 17, --lean-crown 19, --bunch-whorls 20, --short-twigs 22, --float-litter 23.

desk-lamp — the first household piece: procedural balanced-arm desk lamp (stepped cast base, two parallelogram arm sections pinned through knuckle bosses, three tension springs hung on cross bars, domed shade with reflector and lamp, draped flex and plugged cable), whose every joint pin coaxial through the eyes it joins, every spring end seated on its bar, and mass centre over the base footprint are recomputed from the mesh, through the same pipeline. Falsifiers --offset-pin exits 17, --unhook-spring 18, --hollow-base 19, --unscrew-bulb 20.

quad-drone — the first vehicles piece: procedural camera quadcopter (two-tone moulded shell with panel lines, grilles, visor and battery pack, four folding arms hinged on pinned clevises, slotted brushless motors carrying twisted, swept two-blade props, rubber-footed skids, a three-axis gimbal camera), whose motor axes on an exact X, the gap between neighbouring prop discs, every foot on the ground and the mass centre over the landing footprint are recomputed from the mesh, through the same pipeline. Falsifiers --float-foot exits 16, --unlock-arm 17, --long-blades 18, --narrow-skids 19, --drop-lens 20.

soccer-goal — the second sports piece: procedural freestanding 5 × 2 m youth soccer goal (posts and crossbar in one oval aluminium extrusion with a net channel, mitred and welded at the corners, cast corner brackets, foot connectors and rear hubs, sloped supports and a steel ground frame pinned by staples and spikes, a sagging diamond-mesh net with a red head rope through 53 nylon clips, a turf patch with a painted goal line), whose ground bars bedded in the turf, supports seated in their sockets, head rope threaded through every clip, clear mouth size with plumb posts, and catenary sag of the back panel are recomputed from the mesh, through the same pipeline. Falsifiers --float-bar exits 16, --short-support 17, --unclip-net 18, --wide-mouth 19, --taut-net 20.

fallen-log — the second nature piece: procedural fallen forest log (one furrowed lathe along a bowed axis, bark peeled to sapwood scored by beetle galleries, a rotted hollow saw-cut butt with growth rings, a splintered snapped top, broken branch stubs, moss cushions on the top and shaded side, three tiers of bracket fungi, a soil mound with toadstools, ferns and fallen leaves), whose bed along its length, brackets rooted in the bark, mass centre over its contact patch, moss on up- and shade-facing surfaces and ground cover rooted in the soil are recomputed from the mesh, through the same pipeline. Falsifiers --hump-ground exits 17, --float-fungi 18, --tilt-ground 19, --sunny-moss 20, --float-litter 21.

office-chair — the second household piece: procedural ergonomic task chair on a chair mat at a desk corner (polished aluminium five-star base with ribbed spokes and five swivelled hooded twin-wheel casters, a chrome gas lift in a telescoping cover under a synchro-tilt mechanism with tension knob and paddles, a two-tone sculpted cushion with thigh channels, a waterfall front and piped welts in a moulded shell, an elastomeric mesh back and mesh headrest on graphite frames with an S-curved lumbar pad on sliders, 4D armrests, a smoked polycarbonate mat and a snake plant in a stone planter), whose mat flat on the floor with every wheel pressed into it, five-star spacing with plumb swivel stems on one circle, gas-lift column coaxial with hub and socket, mirrored level armrests with seat height and mass centre inside the caster contact hull, single connected chair, lumbar sliders clamped on the frame and leaves rooted in the soil are recomputed from the mesh, through the same pipeline. Falsifiers --float-caster and --curl-mat exit 16, --skew-spoke 17, --offset-column 18, --uneven-arms 19, --loose-wheel 20, --float-lumbar 21, --float-leaves 22.

hover-bike — the second vehicles piece: procedural sci-fi hover bike (a sculpted two-tone fuselage with panel seams, gasketed access panels, a belly service plate, decal plate, charge-port door, heat sink, grab rail and tail light, a stitched pleated saddle, a twin-stanchion fork through sculpted triple clamps with clip-ons, switch pods, pivoted levers and a visored instrument cluster, two glowing exhaust nozzles, two ducted fans with canted stator vanes and handed seven-blade rotors, aerofoil pylons with fastener rows and a conduit, and landing gear of twin-plate pressed links and oleo shocks on 16 pinned joints carrying ski-section skids on wear strips), whose skids on the floor, rotor hubs coaxial with their shrouds, blade-tip clearance to the shroud wall, mirror-symmetric fuselage with seat height, equal blade spacing, mass centre inside the skids' contact polygon, single connected assembly, pins coaxial with their bushings and shock rods coaxial and inside their stroke band are recomputed from the mesh, through the same pipeline. Falsifiers --float-skid exits 16, --offset-hub 17, --long-blades 18, --odd-hull 19, --skew-blade 20, --narrow-skids 21, --pop-lens 22, --offset-pin 24, --skew-rod and --short-rod 25.

weight-rack — the third sports piece: procedural home-gym half rack (punched, numbered square uprights on bolted base plates and padded feet, side rails on bolted flanges, a pull-up bar, J-hooks with UHMW-lined saddles and spotter arms on pull pins, four plate-storage horns, an Olympic barbell with a knurled shaft, collars and sleeves loaded with 20 and 15 kg bumpers and 5 kg iron plates behind spring clips, and two hex dumbbells on the floor), whose pads and dumbbell heads on the floor, pull pins coaxial with their holes, bar seated in both saddles and level, plates coaxial and seated along their sleeves, balanced load and single connected rack are recomputed from the mesh, through the same pipeline. Falsifiers --float-foot exits 16, --offset-pin 17, --float-bar 18, --hook-high 19, --gap-plate 20, --odd-load 21, --loose-horn 22.

boulder-cluster — the third nature piece: procedural glacial boulder cluster (four boulders cut from ellipsoids by cleavage planes with weathered bevels: a speckled granite block, a banded sandstone boulder split in two with matching crack faces and bedding, and a sandstone slab resting flat on a smaller granite boulder, with lichen crusts and moss cushions on the tops and north faces, sunk into a soil mound with grass tufts, pebbles and wildflowers), whose boulders sunk into the soil all round, slab seated on its support and balanced over its footprint, split halves matching across the crack, growth facing up or north and ground cover rooted in the soil are recomputed from the mesh, through the same pipeline. Falsifiers --perch-boulder exits 17, --float-slab 18, --perch-slab 19, --skew-half 20, --sunny-lichen 21, --float-cover 22.

floor-fan — the third household piece: procedural 1950s oscillating pedestal fan (a hollow two-tier cast base on a rubber gasket with a rotary speed switch and badge, a telescoping column with a knurled height-lock collar, a strap yoke with a tilt knob, a slotted motor housing with an oscillation knob, a two-half wire guard of spokes and rings welded to clipped rim rings, four swept brass blades on a hub with a spinner nut, and a cord to a plug), whose rotor and head coaxial with the guard, spokes seated in their rim rings, plumb column on the base's axis, blade-tip clearance, equal blade spacing, tip-over angle and single connected assembly are recomputed from the mesh, through the same pipeline. Falsifiers --offset-hub exits 17, --short-spoke 18, --lean-column 19, --long-blades 20, --skew-blade 21, --hollow-base 22, --loose-spinner 23.

motor-scooter — the third vehicles piece: procedural 1960s Italian step-through motor scooter (a pressed-steel tail with two bulbous side cowls, louvres on the engine side and chrome belt trims, a floorboard with runner strips pressed up into the tail and a leg shield convex in plan, arched into the headset and rimmed in chrome, with a horn cast and grille, a single-sided front end with a raked column, trailing link, coil spring and a crested mudguard, a headset carrying the headlamp, speedometer, grips, levers and mirrors, a two-tone piped dual saddle with a grab strap, 10-inch split rims in block-tread tyres, an alloy engine case with a finned cylinder, silencer and kick-start, a luggage rack, tail lamp and plate, and a centre stand), whose tyres and stand feet grounded, wheel axles level and parallel, steering trail, body mirror symmetry excluding the engine side, wheelbase, mass centre inside the support polygon, single connected assembly and the leg shield seated in the floorboard are recomputed from the mesh, through the same pipeline. Falsifiers --float-tyre exits 16, --toe-wheel 17, --steep-head 18, --odd-body 19, --short-wheelbase 20, --narrow-stand 21, --pop-speedo 22, --lift-shield 23.

bowling-pins — the fourth sports piece: procedural pin deck end of a ten-pin lane (a slab of 39 V-seamed maple boards crossed by the pin-deck joint, ten inlaid pin spots on a 12 in triangle, targeting arrows and range dots, channel gutters, cappings, kickbacks with sloped noses, aluminium caps and kick plates, a steel pit edge and sleepers; ten pins lathe-turned from the regulation profile table with red neck stripes and a crown band; an 8.5 in marbled ball drilled by an exact Boolean with a countersunk thumb hole and two parallel finger holes), whose sleepers grounded, pins centred on their spots, seated, plumb and to size, spots on the exact lattice, turned profile, ball resting on the lane at its radius, hole depths, bores, span and bridge, boards flush and parallel and single connected assembly are recomputed from the mesh, through the same pipeline. Falsifiers --float-sleeper exits 16, --offset-pin 17, --float-pin 18, --lean-pin 19, --wide-rack 20, --fat-neck 21, --float-ball 22, --shallow-holes 23, --proud-board 24, --lift-arrows 25.

pond-edge — the fourth nature piece: procedural pond margin on a raised soil disc (a bank sloping from turf through wet mud into a shallow basin, its cut edge showing its soil horizons; the water its own rippled sheet at a declared level, its rim run on under the bank; a cattail clump of arching strap leaves and five stems, each threaded through a velvet seed head with a bare spike; rush and turf tufts; five notched lily pads and two layered water lilies floating; wet stones, a half-submerged branch, pebbles and fallen leaves), whose leaves and stems rooted in the mud, pads floating at the water level, water level and ripple band, seed heads threaded on their stems, water enclosed by the bank and cover joined to the soil are recomputed from the mesh, through the same pipeline. Falsifiers --float-reeds exits 17, --sink-pad 18, --flat-water 19, --slip-heads 20, --short-water 21, --float-cover 22.

stand-mixer — the fourth household piece: procedural retro tilt-head stand mixer on a honed stone countertop section (a cast enamel base foot, neck and streamlined head lofted from superellipse sections, on four rubber feet; a tilt hinge pinned through two neck knuckles; a chrome trim band, blank badge, speed and tilt-lock levers; an attachment hub with cap and thumb screw; a planetary socket carrying a flat beater into a 4.5 L brushed stainless bowl with a rolled rim and strap handle under three bayonet lugs; a cord to a plug; a whisk, a measuring cup and two eggs in a glazed dish), whose feet on the counter, hinge pin coaxial through its knuckles, bowl seated and concentric on its plate, height and brim capacity, beater coaxial with its socket, beater's dime-test clearance to the bowl, mass centre inside the feet and single connected assembly are recomputed from the mesh, through the same pipeline. Falsifiers --float-foot exits 16, --offset-hinge 17, --offset-bowl 18, --shallow-bowl 19, --offset-beater 20, --long-beater 21, --bunch-feet 22, --loose-cap 23.

cargo-loader — the fourth vehicles piece: procedural sci-fi industrial cargo loader, a bipedal powered-lift exoframe (broad flat feet with rubber soles, grip cleats and toe bumpers; hydraulic legs of lofted box-section shins and thighs pinned at the ankle, knee and hip; arms hung from shoulder yokes on towers; every joint a clevis with a chrome pin through two lug bushings and an eye bushing; eight rams, each a collared cylinder with a chromed rod, a pinned bracket at each end and a hose; fork carriages with hazard-striped faces and forged L-tines; an open roll-cage cockpit with a bucket seat, four-point harness, joystick consoles, amber beacon and work lights; a power pack with a slatted grille, cooling fins, hazard bands, exhaust stacks and cable looms; a corrugated cargo crate held on the tines), whose soles grounded, clevis pins coaxial with their bushings, crate resting on both tines, soles level, ram rods coaxial with their cylinders, rod strokes, mass centre of loader and crate inside the soles' support polygon and single connected assembly are recomputed from the mesh, through the same pipeline. Falsifiers --float-foot exits 16, --offset-pin 17, --lift-crate 18, --tilt-sole 19, --skew-rod 20, --bottom-ram 21, --overload 22, --loose-light 23.

archery-target — the fifth sports piece: procedural archery range target (a compressed-straw boss coiled from rope courses that show on its back and edge, bound with doubled jute twine tight over the crests; an 80 cm ten-zone World Archery face with ring lines, an X ring and a printed X, held by target pins; a timber easel leaning it back 12° on toe skids with knee braces, a ledge with a stop lip on a bolted rail and gussets, a numbered butt board, a strap hinge pinned to a rear leg in a steel ferrule and foot, a splay chain between eye bolts; five arrows in the face, one glancing into the edge, one snapped with its fletched half on the grass, a leather quiver of arrows among grass tufts on a turf patch), whose supports bedded in the turf, hinge pin coaxial with its knuckles, boss seated on its ledge and leaning on both legs, regulation gold height and size, points buried in the straw, fletching clear of the face, vanes at 120°, ring radii of the scoring table, forward tip angle and single connected assembly are recomputed from the mesh, through the same pipeline. Falsifiers --float-foot exits 16, --offset-hinge 17, --lift-boss 18, --high-boss 19, --shallow-arrow 20, --short-arrow 21, --skew-vane 22, --wide-gold 23, --short-skids 24, --loose-pin 25.

cactus-garden — the fifth nature piece: procedural Sonoran cactus garden on a raised sand-and-gravel disc (a 2.2 m saguaro of fourteen pleated ribs with rounded crests, three arms leaving the trunk through a smooth collar and turning up through wide elbows, a corky boot and scars, felt areoles with radiating spine clusters down every crest and cream flowers on the crown; a fishhook barrel cactus with a red hooked central at every areole and a ring of yellow fruit; a prickly pear of twelve broad sage paddles fused pad on pad in four tiers, with glochids and magenta fruit; a blue agave rosette, cleaved sandstone rocks, a bleached branch, fallen saguaro ribs, dry bunchgrass and gravel), whose arms biting into the trunk, pads jointed into their parents, plumb saguaro with its mass over its foot, ribs at equal stations, spines rooted in the skin, plants bedded in the sand and cover joined to the sand are recomputed from the mesh, through the same pipeline. Falsifiers --short-arm exits 17, --shallow-pad 18, --lean-saguaro 19, --skew-ribs 20, --float-spines 21, --perch-barrel 22, --float-cover 23.

espresso-machine — the fifth household piece: procedural prosumer E61 espresso machine on a honed stone countertop section (a black chassis behind a brushed stainless front panel, side panels folded round its edges with louvred vent slots cut through each sheet, a warmer tray with a bent rail and four upturned cups, adjustable feet; the chromed E61 group with its neck, gasket, mushroom cap and a lever pinned through two bosses; a spouted portafilter with a walnut handle; steam and hot-water valves with fluted bakelite knobs and wands on ball joints; twin gauges with printed dials in chrome bezels; a toggle and pilot lamp; a drip tray whose slotted grate carries a shot cup of espresso; a knock box, a tamper and a milk pitcher), whose feet on the counter, lever pin coaxial through its bosses, cups seated on their hosts, body size, portafilter coaxial and seated to the gasket, gauge glasses recessed in their bezels, drip tray inside the footprint, mass centre inside the feet and single connected assembly are recomputed from the mesh, through the same pipeline. Falsifiers --float-foot exits 16, --offset-pin 17, --sink-cup 18, --narrow-body 19, --offset-pf 20, --drop-pf 21, --proud-gauge 22, --shift-tray 23, --bunch-feet 24, --loose-knob 25.

road-bicycle — the fifth vehicles piece: procedural 1970s lugged-steel road bicycle leaning on its side kickstand (a 56 cm diamond frame in chromed, spear-pointed lugs, tapered stays with chrome tips, a chrome-crowned fork with socks; two 700c wheels of 36 spokes laced three-cross from both flanges of small-flange hubs to nipples through box-section rims, quick-release skewers, tan-wall tyres with a file-tread crown; a 52/42 crankset with quill pedals, toe clips and straps, a six-speed freewheel and a roller chain of 112 individual links solved round the ring, the cog and both jockeys; front and rear derailleurs, down-tube shifters, side-pull calipers, gum-hooded levers on cotton-taped drop bars, a quill stem, a leather saddle on rails, a bottle in a bolted cage), whose hubs coaxial with their dropouts, spoke seats in flange and nipple, wheels in the frame's plane, steering trail, three-cross lacing, chain seated on ring and cog, straight chain line, mass centre inside the tyres-and-foot triangle and one connected assembly are recomputed from the mesh, through the same pipeline. Falsifiers --float-tyre exits 16, --slip-wheel 17, --short-spoke 18, --dish-wheel 19, --steep-head 20, --bunch-spokes 21, --lift-chain 22, --shift-rollers 23, --tuck-stand 24, --pop-bottle 25.

skate-ramp — the sixth sports piece: procedural backyard quarter-pipe, 1.2 m on a 1.8 m transition (five plywood transition templates on 2x4 sills with sistered studs and a back post, nine 2x4 stringers under a two-layer plywood skin with joints offset between layers and landing on stringers, screw rows over every stringer, a steel coping pipe on welded, bolted tabs, a steel kicker plate ground to a lip on a toe block, a worn stencilled roundel and wheel marks; a skateboard on the deck with a seven-ply concave deck, kicktails, grip tape, two trucks and four wheels on bearings), whose sills on the floor, templates seated on sills and under the skin, wheels on the deck, circular transition, coping reveal, flush kicker plate, staggered seams, screws over stringers, coaxial wheels and one connected assembly are recomputed from the mesh, through the same pipeline. Falsifiers --float-sill exits 16, --short-rib 17, --small-wheel 18, --sag-skin 19, --sink-coping 20, --proud-plate 21, --stack-seams 22, --miss-screws 23, --skew-wheel 24, --lift-grip 25.

palm-tree — the sixth nature piece: procedural coconut palm on a raised disc of rippled beach sand (a 4.47 m trunk rising from a swollen, lobed bole with a mat of 24 roots flaring out into the sand, leaning along a curve and coming back upright under the crown, tapering, ringed with 25 leaf scars at an even pitch; a fibrous boss of leaf bases carrying eighteen pinnate fronds in a golden-angle spiral, each a curved, drooping rachis with 36 pairs of folded leaflets hanging below it in a V, young fronds rising and old ones hanging; two dead fronds, two spear leaves and twelve green and ripening coconuts in bunches under the frond bases; two fallen coconuts, a fallen frond, driftwood, seashells and sea grass), whose fronds seated in the crown, coconuts attached under it, trunk height and lean with the crown's mass inside the root plate, leaf-scar rings at an even pitch, trunk and roots bedded in the sand, fallen coconuts resting in it and beach litter joined to it are recomputed from the mesh, through the same pipeline. Falsifiers --short-petioles exits 17, --drop-coconut 18, --short-roots 19, --bunch-rings 20, --perch-trunk 21, --float-nuts 22, --float-cover 23.

wingback-armchair — the sixth household piece: procedural reading corner on a fringed wool rug (a Queen Anne / Chesterfield wingback in oxblood leather: a reclined back deep-button tufted with thirteen buttons on a diamond lattice, each seated in a funnelled dimple, the leather puffed into pillows and folded into sharp pleats along every line joining two buttons; wings sweeping forward into rolled arms with a tucked English roll, crowned scroll fronts, piped welts and rows of brass nailheads, a nailed front rail, a loose crowned cushion with piped welts on both seams, cabriole front legs on pad feet and splayed rear legs in brass ferrules; beside it a walnut tripod side table with a brass reading lamp, a linen shade and two cloth-bound books), whose feet sunk into the rug, legs tenoned into the body, buttons seated in their dimples, mirror symmetry and size, diamond lattice, table's mass centre inside its feet, cushion resting on the deck and evenly spaced, seated nailheads are recomputed from the mesh, through the same pipeline. Falsifiers --float-foot exits 16, --short-legs 17, --sink-buttons 18, --odd-wing 19, --drift-buttons 20, --narrow-tripod 21, --lift-cushion 22, --bunch-nails 23.

planet-rover — the sixth vehicles piece: procedural six-wheeled planetary science rover on a patch of rocky red-grey regolith (a cream warm-electronics body with quilted gold-foil blankets, a deck of instrument boxes, inlets and a calibration target, a finned power unit on struts between two radiator banks; a rocker on each side pivoting on a boss in the body and a bogie pinned in a clevis on its front end, the two rockers linked through a differential bar on the deck; six drum wheels with 24 chevron grousers, curved flexure spokes and drive actuators, the four corners on steering actuators; a camera mast, a high-gain dish on a two-axis gimbal, a whip; a 5-DOF arm drilling a boulder; harnesses along every leg; ruts behind the wheel lines and 19 broken rocks), the regolith fitted so every wheel sinks 11–19 mm into it. --float-wheel exits 16 on every wheel sunk in band, --offset-pin 17 on the pivot pins coaxial with their bushings, --sink-grousers 18 on the grousers seated on the drum, --lean-mast 19 on the mast plumb and the rover's size, --jam-rocker 20 on the rockers equal and opposite through the differential, --offset-steer 21 on the steering axes through the wheel centres, --camber-wheel 22 on the axles level and lateral, --bunch-grousers 23 on the grouser pitch, --overload-turret 24 on the mass centre inside the support polygon by the 45° tip margin, --loose-dish 25 on one connected assembly, while the envelope holds.

traffic-cones — the seventh vehicles piece: procedural roadworks set on a cut-out patch of asphalt (a broken edge, a worn white road line and two sealed tar cracks; seven 720 mm PVC cones, each a hollow lathed body with a moulded bead and a rolled lip round an open tip, bonded into a square rubber base with chamfered corners, a raked top, a collar, four lugs and a recess underneath, and hooped with two retroreflective collars; three standing in a taper line, three nested in a stack and one knocked over onto the edge of its base and its lip; a folding A-frame barricade of four square steel legs hinged in pairs on pivot bolts, spread by pinned straps, footed in rubber pads, with two striped boards bolted to each face and a warning lamp with amber fresnel lenses on a bracket), the cone wall sized so each cone in the stack bears 1 mm on the one below at a 36 mm pitch. --float-cone exits 16 on every support bedded in the slab, --gap-board 17 on the boards biting their legs, --float-band 18 on the collars seated on their bodies, --lean-cone and --skew-leg 19 on the cones plumb at real size and the legs mirror-symmetric, --loose-stack 20 on the nesting pitch and wall bite, --loose-lamp 21 on one connected assembly, while the envelope holds.

mushroom-stump — the seventh nature piece: procedural felled-tree stump on a sloping forest-floor soil disc (one furrowed lathe about a plumb axis flaring through five buttresses into the ground, plated bark peeled to sapwood in two patches, a level saw cut with weathered growth rings round a dark heartwood, radial drying checks notching the rim and a strip of torn holding wood with long splinters, five surface roots lying in the soil and diving into it, moss on the shaded flank, two tiers of turkey-tail brackets, three fly agarics with warted caps, pleated gills, a volva and a hanging skirt, two clusters of ringed honey fungus out of a root and the stump's foot, fallen leaves, ferns, twigs and pebbles), whose foot sealed in the soil all round, caps seated on their stipes, level cut and stated size, roots bedded along their run, stipes rooted in their soil or wood, brackets rooted in the bark, moss on up- and shade-facing surfaces and ground cover joined to the soil are recomputed from the mesh, through the same pipeline. --perch-stump exits 17 on the stump sealed all round, --float-caps 18 on every cap seated on its stipe, --tilt-cut and --fat-stump 19 on the level cut and stated size, --arch-roots 20 on the roots bedded, --float-mushrooms 21 on every stipe rooted in its host, --float-brackets 22 on the brackets rooted in the bark, --sunny-moss 23 on moss facing up or into the shade, --float-cover 24 on the ground cover joined to the soil, while the envelope holds.

go-kart — the eighth vehicles piece: procedural rental go-kart on a patch of kart-track asphalt against a red and white kerb (a 30 mm tube chassis whose main loop is one bar swept round every bend, cross tubes ending inside the rails with welded gussets, bearing hangers and kingpin C-brackets; spindles on kingpin bolts with 14° caster; a three-spoke wheel on a raked column in a bushing, a steering plate and two tie rods on rod-end eyes; a bolted nose, side pods on nerf bars and a curved front panel; a moulded seat on stays, a floor tray, two pedals, a strapped fuel tank with its line and a lead ballast block; a finned four-stroke clamped to the right rail with a pull-start, air-box and silencer, driving the live rear axle through a clutch, an 88-link chain solved to a whole number of pitches and a 60-tooth sprocket; bearing carriers, a brake disc and caliper; a tubular rear bumper; four loaded slicks on split rims with valve stems, the fronts narrower than the rears), whose tyres pressed into the asphalt in one plane, hubs and bearings coaxial with their axles, tie-rod eyes on their pins, tyre beads and chain seated, frame, bodywork and wheels mirrored at the stated wheelbase and tracks, caster, mass centre inside the support polygon and one connected assembly are recomputed from the mesh, through the same pipeline. --float-tyre exits 16 on every tyre grounded, --cock-hub, --drop-bearing and --short-tierod 17 on joint fit, --sink-tyre and --lift-chain 18 on the bead and chain seats, --toe-wheel, --wide-track, --odd-frame and --no-caster 19 on mirror, size and caster, --aft-ballast 20 on the stance, --loose-ballast 21 on one connected assembly, while the envelope holds.

broadleaf-oak — the eighth nature piece: procedural mature, open-grown English oak on a sloping grassy soil disc (a short fluted, ridged trunk flaring through six buttresses into surface roots bedded in the soil, a low fork into five crooked scaffold limbs that divide three more times into 260 tapered branches, each seated in its parent and narrowing past every junction by its child's area, a broad domed crown of 1370 lobed oak leaves in clusters on every twig tip, dead twigs, acorns with scaly cups and glossy nuts hanging on stalks and lying in the grass among curled fallen leaves, tufts and sticks), whose branch seats, da Vinci taper, nuts seated in their cups, plumb trunk and balanced crown, foot and roots sealed in the soil, leaves carried by their twigs, acorns hung on their stalks and ground cover joined to the soil are recomputed from the mesh, through the same pipeline. --float-branches exits 17 on every branch seated in its parent, --pop-nuts 18 on every nut seated in its cup, --lean-crown 19 on plumb and balance, --fat-twigs 20 on the taper and area rule, --perch-trunk and --arch-roots 21 on the trunk and roots sealed in the soil, --orphan-clump 22 on every leaf cluster carried by its twig, --drop-acorns 23 on the hanging acorns on their stalks, --float-cover 24 on the ground cover joined to the soil, while the envelope holds.

farm-tractor — the ninth vehicles piece: procedural mid-century utility tractor standing in the ruts of a muddy farmyard with a puddle between its wheels (a cast-iron backbone of engine, bell housing, gearbox and rear axle housing with trumpets; a front axle oscillating on a pivot pin through the front support's lugs and two bushings, kingpins, spindles and a tie rod; 1.240 m rear tyres with 44 chevron bars rooted in the carcass and handed for forward travel, on dished rims with welded clamp lugs and cast-iron half-moon weights; ribbed front tyres; a grille shell with radiator and headlamps, a louvred bonnet, fuel tank and dash; a vertical exhaust stack with a hinged rain cap and an oil-bath pre-cleaner bowl; a raked steering column, a pan seat on a leaf spring, pedals and footplates; mudguards with a tail lamp and a work lamp; a three-point linkage with lift arms, lift rods, lower links, a stowed top link and the drawbar, and a PTO stub under its shield; paint chipped to primer at its edges, rust-streaked, sun-faded and mud-splashed). Asserts 122272 tris, twelve materials with face floors, zero coplanar cross-shell pairs, every tyre sunk 18–45 mm into the mud, hubs and the pivot pin coaxial, 14 link eyes on their pins, beads seated, 88 bars rooted and evenly pitched with their apex leading, body and wheels mirrored, wheelbase, tracks and rear-tyre diameter at their stated size, the mass centre inside the support triangle of the rear contacts and the front pivot by a quarter of the track, and one connected assembly; --float-tyre exits 16, --cock-hub, --cant-pin and --unpin-link 17, --sink-tyre and --float-lugs 18, --skew-wheel, --wide-track, --tall-lugs and --odd-fender 19, --bunch-lugs 20, --reverse-lugs 21, --offset-pivot 22, --loose-lamp 23, while the envelope holds.

fern-mossy-rock — the ninth nature piece: procedural shaded woodland corner on a sloping soil bank (a gritstone boulder cleaved into broken, weathered faces and split by a deep crack, sunk into the bank all round, a thick moss cushion over its crown draped down its shaded front as a conforming shell with a lumpy rim tucked into the stone, a male fern's shuttlecock crown of eleven bipinnate fronds whose 434 alternate pinnae are cut into pinnules and taper to the tip, three fiddleheads unrolling as logarithmic spirals from a scaly rootstock bedded in the soil, a smaller fern growing out of the crack, and beech litter, pebbles, a twig and wood sorrel at the foot), whose rooted fronds and rootstock, moss thickness over the stone, boulder sealed in the bank, moss facing up or into the shade, crack fern wedged in the cleft, pinna alternation and taper, true spirals and ground cover are recomputed from the mesh, through the same pipeline. --float-fronds and --lift-crown exit 17 on every frond rooted in its crown and the crown sealed in the soil, --float-moss 18 on the moss cushion's thickness band on the stone, --perch-rock 20 on the boulder sealed all round, --sunny-moss 21 on moss facing up or into the shade, --perch-crack-fern 22 on the crack fern rooted in the cleft, --flat-taper and --opposite-pinnae 23 on pinnae alternating and tapering along the rachis, --open-crozier 24 on every fiddlehead a real spiral, --float-cover 25 on the ground cover joined to the soil, while the envelope holds.

Examples

Runnable, smoke-gated demos live in examples/ — each is executed headless on Blender 5.2 LTS and 4.5 LTS by the blender-smoke workflow (5.1 on the weekly cron, the needs-5.1 PR label, or manual dispatch), so the screenshots reflect code that actually runs. Browse them all with filters and full-size renders in the examples gallery, or expand a category below.

Grease pencil rosette: five nested neon rose curves mounted as a sign on a brass-framed black lacquer board Parent inverse orrery: a brass tabletop orrery with a glowing yellow sun and three planets Compositor glare: three neon rings with colored bloom halos Image pixels testcard: a studio monitor showing a procedural broadcast test card

Materials, shading & compositing — 7 examples
Swatch grid: six material spheres on a two-tier walnut riser, each labelled by an engraved brass plaque — mirror gold, copper and red plastic behind; blue plastic, a glowing emissive globe and white rough in front

swatch-grid

A procedural-materials swatch grid — Principled metal and dielectric, the emission pattern, and the cross-version set_specular shim. Doubles as a live proof of the EEVEE engine-id mapping (BLENDER_EEVEE on 5.x, BLENDER_EEVEE_NEXT on 4.2-4.5).
Shader node group: five speckled stoneware mugs in oxblood, amber, celadon, teal and cobalt sharing one DippedGlaze node group with different Tint parameters

shader-node-group

One reusable DippedGlaze group declared via tree.interface.new_socket, instanced in five materials with different Tint values. Witnesses the grouping contract: shared datablock (users == 5), parameters on the group node — five mugs share one foot band, dip line and speckle, and differ only in colour.
Compositor glare: three neon rings - violet, cyan, and amber - with colored bloom halos and mirrored reflections on a dark studio floor

compositor-glare

Bloom through the compositor on both sides of the 5.0 rewrite — a Glare (Fog Glow) node fed by Render Layers, wired via scene.compositing_node_group on 5.x and scene.node_tree on 4.x. Witnesses with pixels that the halo falls off strictly with the compositor on and is exactly zero with it off — and that EEVEE has no use_bloom.
Color attribute wheel: a domed ceramic HSV color wheel plate with a white center fading into a vivid rainbow rim, ringed in brass and standing on a walnut easel on a dark studio floor with a warm light pool behind it

color-attribute-wheel

The modern color-attributes API — mesh.color_attributes.new() on the CORNER domain, not the deprecated vertex_colors alias, filled by expanding per-vertex HSV across face corners with foreach_get/foreach_set. Asserts the attribute is sized to loop count (not vertex count), is active_color, and that the shader Attribute node is actually linked to Base Color.
Image pixels testcard: a hooded broadcast reference monitor on a walnut desk showing a procedural broadcast test card — seven neon color bars behind the classic dark circle, a luminance ramp, and a PLUGE row with a white bottom-left origin marker — in a dark studio with a warm pool raking the back wall

image-pixels-testcard

A procedural broadcast test card written into bpy.data.images.new() with one pixels.foreach_set() call. Asserts the buffer is always flat RGBA (channels == 4 even with alpha=False), that byte storage quantizes at exactly ≤ 0.5/255 and strictly > 0 while float_buffer=True round-trips at float32 precision, that scale() reallocates (stale-size reads raise), and the save() trap: source silently flips to FILE, the buffer drops, and later pixels reads come from whatever sits on disk — proven with an imposter file. save_render() is the non-destructive path.
PNG vs EXR alpha: two thin-bezel monitors on a walnut-topped console in a dark studio — left the float→PNG false-unpremul mangling clamps dark rows to white, right the EXR-clean straight buffer, brass desk plates reading FLOAT → PNG and FLOAT → EXR

png-exr-alpha

float_buffer=True images saved to PNG are written as RGBA16 and unpremultiplied as if associated-alpha — straight-authored dark values at low alpha clamp to white (closed-form error 0.98 at (0.02, a=1/255)). OpenEXR preserves float RGBA; byte images stay straight 8-bit. Also witnesses EXR color_mode='RGB' dropping alpha.
Sky texture sun elevation: diptych of a red-granite obelisk on a paved plaza lit only by the sky — left panel sun at 8 degrees, navy dusk with an orange horizon glow and the obelisk face raked orange, right panel sun at 55 degrees, bright blue midday sky, sunlit paving and a short shadow

sky-texture-sun-elevation

World ShaderNodeTexSky driving Background Color — the sky contract AI lighting code misses across 4.5 → 5.1. sky_type is NISHITA on 4.5 LTS and MULTIPLE_SCATTERING on 5.1 (NISHITA gone); dust_density exists only on 4.5 (aerosol_density on 5.1). Two tiny Cycles EXR zenith probes assert sun_elevation 8° → 55° brightens zenith (rise 2.25x / 1.50x, gate ≥ 1.25). Gallery still is a sky-lit obelisk diptych (8° dusk | 55° midday) so the contract reads at thumbnail scale.
Mesh, curves & text — 13 examples
Bmesh gear: a brass 14-tooth gear in a small gear train, meshing with a blued 8-tooth pinion and a spoked 22-tooth gunmetal wheel, each bolted through a hub boss to a dark steel backplate on a walnut plinth

bmesh-gear

A 14-tooth gear built entirely with bmesh — with bm.free() in a try/finally, as the ownership contract demands. Asserts the closed-form vert/edge/face counts and that the result is watertight (every edge borders exactly two faces).
UV layer grid: two walnut-framed tile panels on oak studio easels with brass placards — left, NO UV LAYER, one flat teal face (the calc_uvs silent no-op hazard), right, UV LAYER FIRST, a saturated magenta-cyan checker (the pre-create repair), under a warm wall pool

uv-layer-grid

bmesh.ops.create_grid(..., calc_uvs=True) is a silent no-op unless a UV layer already exists — without one an Image Texture samples texel (0, 0) everywhere. Asserts the hazard, the pre-create repair against closed-form grid UVs, and an explicit assignment fallback — then re-reads its own render and fails unless the pixels prove the flat-vs-checker split.
Wave displace: a cast bronze tile in a walnut frame whose top is displaced into smooth standing-wave crests, verdigris pooled in the troughs

wave-displace

Bulk vertex IO at real scale — 9,409 vertices displaced into a standing wave with one foreach_get and one foreach_set, no per-vertex access. Asserts the count is unchanged, the Z span matches the amplitude, and a probe vertex matches the closed-form wave.
Shape-key blend: three cobalt-glazed ceramic vases with an ochre band on a dark studio floor - the same vase at Tall shape-key values 0, 0.5 and 1, squat jar to amphora to flared trumpet vase, left to right, with thin pale rings of the jar's belly around the tallest

shape-key-blend

A relative Tall shape key that turns a squat ceramic jar into a trumpet vase, lifting and flaring the rim — authored through shape_key_add / key_blocks / .value. Witnesses that shape keys do not rewrite mesh.vertices: every evaluated vert matches basis + value × (key − basis).
Curve bevel arc: a red horseshoe magnet built from one beveled Bezier curve, its filled end caps turned to the camera as steel pole faces, iron filings arcing between the poles and Bezier-wire paper clips clinging to them

curve-bevel-arc

A beveled Bezier semicircle authored on bpy.types.Curve — splines.new('BEZIER'), bezier_points, bevel_depth, use_fill_caps — so the curve renders as a solid tube without a prior mesh conversion — staged as a horseshoe magnet whose capped ends are the pole faces. Asserts eight points, bevel_depth == 0.15, and evaluated topology 1044 verts / 1028 faces.
Text version stamp: beveled gold version numerals standing on a chamfered dark stone plinth with a BLENDER caption on a brushed-steel nameplate — the body text is the live bpy.app.version_string

text-version-stamp

A beveled 3D stamp of the running Blender version — a TextCurve whose body is the live bpy.app.version_string, so every render self-documents which Blender made it. Asserts the TextCurve solids closed form (evaluated z-extent = 2 × (extrude + bevel_depth), bevel widening the outline by 2 × bevel_depth), that flat text is filled but planar, that body edits regenerate geometry, that version_string is not bare semver on LTS builds ("4.5.11 LTS"), and that a Mesh reference dies at to_mesh_clear().
Depsgraph-evaluated export: the sparse control cage of a game controller drawn as orange wire and vertex beads over faint blue facets, beside the smooth subdivided cobalt controller with sticks, d-pad and colored face buttons that the OBJ export contains, on a dark studio floor with a warm light pool behind

depsgraph-export

A depsgraph-evaluated export — builds a game controller whose shell is a 90-vertex quad cage under SUBSURF, measures every mesh via evaluated_get().to_mesh() / to_mesh_clear(), asserts the evaluated shell matches the Catmull-Clark closed form (1,410 vertices), and asserts wm.obj_export ships the modifier-applied geometry (exported vertex count == evaluated > base).
check-only, no gallery still — no geometry

eval-mesh-datablock-name

evaluated_get().data.name is generic Mesh on 4.5.11 and 5.1.2 and equals the source name on 5.2.1. to_mesh().name stays the source name on all three. --assume-distinct-names is red only on 5.2.
USD export evaluation_mode: two brass goblets on dark plinths, each re-imported from its own USDA file — left an eight-sided 130-point VIEWPORT export, right a smooth 8450-point RENDER export

usd-export-evaluation-mode

wm.usd_export evaluation_mode='RENDER' versus 'VIEWPORT'. TESSELLATE writes the closed-form Catmull-Clark counts (26/24 vs 98/96); default BEST_MATCH writes the 8-vert cage and the mode is silent. Asserts the USDA point counts, not the still.
VSE cut list: a reference monitor showing the two-by-two program wall — crimson, teal, and amber color strips plus the mid cross-blend cell, composited by the sequencer over a scene strip — above a timeline console laying out the same strip spans as coloured blocks with handle notches and a playhead

vse-cut-list

The sequencer API rename from 4.5 LTS to 5.x — strips (never .sequences), new_effect ending in length= vs frame_end=, and left_handle/right_handle/duration replacing the deprecated frame_final_*. Asserts closed-form spans, GC wiring and clamping, the consumed-input compositing contract, and a save/reload round-trip.
Light link studio: two identical porcelain chess kings on dark plinths, the LINKED king glowing under an amber key with a warm floor inlay beneath it, the UNLINKED king cool grey beside it - one key light restricted to the hero collection

light-link-studio

Object light linking proven in pixels: a key linked to the hero's collection lights only the hero (4.0x luminance ratio at projected centers), and unlinking in the same check raises the decoy 244% with 0.0% hero drift. The API is obj.light_linking — the Light datablock has none — and EEVEE Next honors linking too (measured), with Cycles pinned for deterministic samples.
VSE gamma cross: a hooded grading monitor on a walnut riser beside a three-trackball control surface, its screen showing every frame of an orange-to-azure cross as two filmstrips - the GAMMA_CROSS strip on top sinking to dark grey at mid-cross, the linear CROSS strip beneath passing through violet

vse-gamma-cross

The GAMMA_CROSS fade is not the naive linear mix: it blends in a gamma-0.5 space, ((1-t)·√A + t·√B)² with t = (frame − start) / duration — never 1 inside the effect. Per-frame sample renders assert the closed form (mid dips 0.250 below the sRGB lerp), and the AgX-default sampling trap is documented (view_transform = 'Standard' is mandatory for any pixel witness).
check-only, no gallery still — no geometry

vse-linear-modifiers

ColorStrip.use_linear_modifiers is a bool on 4.5.11 and 5.1.2; the same getattr is AttributeError on 5.2.1. Version-guarded hasattr then read exits 0 on all three. --assume-present is red only on 5.2.
Geometry Nodes — 7 examples
Geometry Nodes SDF remesh: a vase kitbashed from overlapping clay primitives beside the same kit fused by the SDF remesh into one cobalt-glazed shell

gn-sdf-remesh

A Geometry Nodes SDF remesh (MeshToSDFGrid → GridToMesh at the SDF zero-level). Witnesses the fix that an SDF grid is meshed with Grid to Mesh, not Volume to Mesh, and that a Set Material node carries the material through the remesh.
GN instance grid: a cobalt-blue 3x3 macropad whose nine cream keycaps are instanced onto a Geometry Nodes Mesh Grid, one orange accent key picked out by a position-field Set Material

gn-instance-grid

A generative Geometry Nodes tree — Mesh Grid → Instance on Points (a modeled keycap via Object Info) → Realize Instances — attached as a NODES modifier with no Group Input. Asserts evaluated topology is verts = faces = 1089 (9 keycaps × 121), and a position-field Set Material lands the orange accent on exactly one keycap.
GN modifier inputs: three spiral staircases from one shared Geometry Nodes tree, 1, 2 and 3 meters tall with 7, 17 and 27 oak treads, proving per-modifier Height writes land on 5.2 RNA and on 4.5 dict assignment

gn-modifier-inputs

One Geometry Nodes spiral-staircase tree, three modifier copies. Writes a Float Height input through mod.properties.inputs on 5.2 and mod[identifier] on 4.5/5.1; the tree turns 1 / 2 / 3 m into 7 / 17 / 27 treads. Asserts readback and evaluated Z-extent equal 1 / 2 / 3. The 5.1 dict form raises TypeError on 5.2.
GN zone iterate: four amber-to-red blocks on a walnut plinth (Repeat Zone) beside a spindle of six teal-to-mint blocks (For Each Element) on a dark studio floor, proving pair_with_output actually iterates

gn-zone-iterate

Repeat Zone and For Each Element only iterate after pair_with_output. Asserts evaluated cubes against closed forms — Repeat 8×(1+N) with X-centers at k×1.2, For Each 8×P with Z-centers at i×0.6+0.21 — not that the zone nodes exist. Unpaired evaluates empty; For Each's main Geometry socket is a passthrough.
GN simulation fountain: a two-tier sandstone fountain whose twenty jets are strings of cyan droplet beads, each bead a stepped Simulation Zone position threaded on its thin closed-form ballistic arc

gn-sim-fountain

A Simulation Zone integrates twenty jets under gravity with the exact constant-g update, and every stepped frame lands on p0 + v0 t - g t^2/2 (worst 6.6e-7 m). Two silent traps, identical on 4.5, 5.1 and 5.2: a direct frame_set(N) jump runs one step, not N; and calculate_to_frame returns PASS_THROUGH headless and leaves interpolated frames. Only a bake gives random access.
GN socket rename: a brushed copper height-gauge column on a granite surface plate, graduated every 0.1 m from its stored gauge_h attribute, with a brass scriber resting on a stack of steel gauge blocks

gn-socket-rename

Compare INT and Random Value FLOAT socket identifiers collapsed in 5.2 (A_INT / Min_001 gone; A / Min reused). Enabled-name lookup wires on 4.5, 5.1, and 5.2. Asserts 16 verts and POINT gauge_h=1.80 on eight column verts. --legacy-ids is red only on 5.2.
check-only, no gallery still — item-name round-trip is not thumbnail-legible

gn-bundle-roundtrip

Combine / Separate Bundle on 5.x (NodeCombineBundle, not GeometryNodeCombineBundle). Asserts evaluated 8/6 plus x-extent [0.5, 2.5] and POINT bundle_mark=0.314159 — count-only is a cube that never entered the bundle. Skips 4.5 (min_version 5.0); --force-run fails creating the 5.x RNA.
Animation, rigging & constraints — 6 examples
Turntable: a copper Suzanne on a lathed display turntable with a vented motor base, a platter rim ticked once per keyed frame, and an amber arrow showing the keyed turn

turntable

A slotted-actions Z-rotation turntable keyed through the cross-version channelbag path (get_channelbag_for_slot). Witnesses the slotted-actions fix: ensure-helper channelbag on 5.x, strip.channelbag on 4.4/4.5.
Driver wave: a pipe-organ facade of sixteen brass pipes on a walnut windchest whose heights form a sine wave, each driven by a driver_namespace function

driver-wave

A driver_namespace function driving sixteen column heights through SCRIPTED drivers. Witnesses the evaluation contract: driven values appear after a view-layer update on the evaluated copy and the flushed-back original, and both must match the closed form.
check-only, no gallery still — no geometry

exit-pre-sidecar

bpy.app.handlers.exit_pre writes $BDT_SMOKE_SIDECAR as Blender dies; the harness asserts exit_pre-ok after the process exits. Skips 4.5 (min_version 5.1). --silent-handler / --no-handler miss the file; --wrong-text / --write-in-main fail the content check.
Damped Track aim: twelve red-and-brass spotlight heads on stands in an open ring, each lens constrained to face a glowing amber orb on a brass pedestal

damped-track-aim

Aim constraints via the data API — Object.constraints.new('DAMPED_TRACK') with target and TRACK_Z, not bpy.ops.object.constraint_add in a headless loop. Asserts twelve unmuted Damped Track constraints and evaluated local +Z alignment toward the core (dot ≥ 0.998).
Armature bend: three ribbed bellows hoses on steel foot flanges showing rest, half, and full curl under a four-bone armature, per-bone weight bands blending teal through amber to coral at the joints

armature-bend

A four-bone chain built with edit_bones skins a tapered tube through name-bound vertex groups, posed into a curl and read back through the depsgraph. Asserts that edit_bones is empty outside edit mode, and that the armature modifier is exactly linear blend skinning — every evaluated vertex equals Σ wᵢ · (pose_bone.matrix @ bone.matrix_local.inverted()) @ rest, with the root ring pinned and the tip deflected. A straight tube is a failure.
Parent inverse orrery: a brass tabletop orrery with a glowing yellow sun, three planets on pivot arms inside brass orbit rings, and a silver moon, on a dark studio floor

parent-inverse-orrery

A brass orrery parented entirely through the data API — the keep-world idiom child.parent = pivot; child.matrix_parent_inverse = pivot.matrix_world.inverted() carries arms, planets, and a two-level moon through spinning pivots. Asserts bare .parent = really teleports, matrix_world is stale until view_layer.update(), and every orbit lands on its closed form.
Context & Grease Pencil — 5 examples
Temp-override join: a red enamel hurricane lantern with a glowing amber globe, wire guard, brass knob and wooden bail grip, joined from seven parts into one object

temp-override-join

A hurricane lantern joined from seven part objects under bpy.context.temp_override — the supported replacement for the removed context.copy() dict-pass form. Asserts one mesh remains, sources are gone, and the five part materials merge with every face kept on its own.
Cross-version property delete: two stage lamps on one stand — the left lamp keeps its ID property and glows, lighting a placard reading obj["accession"] = 42; the right lamp had del obj["accession"] and stands dark

cross-version-property-delete

Custom ID properties are removed with del id_block[key], not property_unset. IDs are built with bpy.data.objects.new — the snippet __main__ keys off active_object and is dark headless. Same del on 4.5 LTS and 5.x.
check-only, no gallery still — no geometry

mesh-automasking-settings

MeshAutomaskingSettings is absent on 4.5.11 and 5.1.2, present on 5.2.1. Old Brush automasking attributes are gone on 5.2; read .mesh_automasking_settings instead. --assume-brush-attrs is red only on 5.2.
Grease pencil rosette: five nested neon rose curves drawn as tapered Grease Pencil v3 strokes, cyan through magenta to red, mounted as a neon sign on a brass-framed black lacquer board and washing it with coloured spill

grease-pencil-rosette

Five nested rose curves drawn with the Grease Pencil v3 attribute API — layer → frames.new(1).drawing → add_strokes → per-point position, radius, opacity, and vertex color. Asserts the GPv3 address break: on 4.5 GPv3 is grease_pencils_v3 while grease_pencils is still legacy; on 5.x legacy is gone and GPv3 owns the name. Point writes lazily materialize attribute layers, and every position round-trips through the raw POINT buffer.
GP Line Art contour: a cel-shaded red-and-white lighthouse on a rocky islet with a keeper's cottage and rowboat, inked in bold black Grease Pencil Line Art strokes, proving modifiers.new LINEART with source_object evaluation

gp-lineart-contour

Grease Pencil LINEART modifier ink via the depsgraph on a cel-shaded lighthouse diorama — not Freestyle and not hand-drawn strokes. source_object is load-bearing (clear → 0 strokes); every edge type off → 0; the drawing is 255 strokes / 1393 points on all three binaries, gated so dropping any one edge type fails. Stroke width: thickness exists on 4.5, AttributeError on 5.1 — portable path is radius.
Game asset pipeline — 22 examples
glTF export round-trip: one olive-drab sci-fi supply crate on a dark studio floor, its right half traced by an amber wire cage of the re-imported glTF triangles that lands exactly on every bevel, rivet and vent slat, proving the export/import round-trip preserves the asset

gltf-export-roundtrip

A game-prop supply crate round-tripped through bpy.ops.export_scene.gltf and the importer — the check reads the .gltf JSON and .bin buffer directly. Witnesses the +Y-up convention baked into vertex data with no node rotation, export_apply shipping the evaluated mesh (one disk vertex per evaluated loop), V-flipped UVs, and per-triangle material bindings — all against the depsgraph-evaluated mesh. The exporter/importer RNA signatures are probed byte-identical on 4.5.11 and 5.1.2 and guarded against future renames.
Export preset axis: a red-and-white radio mast exported under Unity and Godot glTF presets and re-imported side by side on a dark studio floor, each beside a red-green-blue axis gizmo - Unity standing with blue Z up, Godot lying with green Y up and blue Z along the mast - proving the two files have different vertex orientation

export-preset-axis

The same radio-mast mesh under the Unity (export_yup=True) and Godot (export_yup=False) glTF presets. Re-importing each file proves the axis conversion: Unity stands, Godot lies along -Y. --same-axis exports both Y-up and the differ check exits 9. Neighbor of gltf-export-roundtrip.
LOD decimate chain: three identical cream-and-red retro rockets with brass trim and a porthole on a dark studio floor, each under a dark triangle wireframe that coarsens left to right, labelled 4784, 2392 and 860 tris

lod-decimate-chain

One recognizable asset at three LODs via DECIMATE modifiers evaluated through the depsgraph. Asserts the reduction is non-destructive (the original datablock keeps its closed-form counts), each LOD's evaluated triangle count lands within 5% of ratio x base (measured 0.00–0.13%), and the silhouette-critical bbox survives within 1e-3 — with a stacked Decimate and an oblique fin's shaved plate corner as the caught failure modes. A wireframe of each evaluated mesh makes the density drop visible.
Bake normal high to low: an unlit tangent-space normal map card, the 3200-tri ribbed bronze source plate, and the 900-tri collapse-decimated plate wearing that map, captioned on a dark studio floor

bake-normal-high-to-low

Cycles cage-bakes a ribbed hatch onto a DECIMATE COLLAPSE LOD. Asserts the map is not flat (frac 0.7211, MAD 0.09356 vs (0.5, 0.5, 1.0)) while a flat-source control is (frac 0.0000). --flat-source exits 5. Byte-identity across 4.5 / 5.1 / 5.2 is not the contract — Cycles bake is stochastic. Neighbor of lod-decimate-chain.
Vertex weight limit: an orange industrial robot arm reaching down with a two-jaw gripper, painted with its own post-limit skin weights - each rigid segment glows in its bone colour and the back cables grade blue to teal to violet to magenta across the joints

vertex-weight-limit

The game-engine max-four-bone-influences constraint, enforced through the data API (v.groups + VertexGroup.remove + renormalize) rather than the bpy.ops.object.vertex_group_limit_total context path. Asserts the pre-limit cables really carry five influences, no vertex ends over the cap, weights still sum to one, the pose survives pruning, and the modifier is still exact linear blend skinning read back from the mesh's own deform layer. The render paints those post-limit weights onto the arm as a colour attribute.
Triangulate and tangents: a machined steel buckler on a walnut stand - pointed brass boss, domed face cut with concentric lathe grooves, riveted brass rim - proving the mikktspace tangent field a normal map depends on

triangulate-tangents

The normal-mapping tangent-space contract: deterministic triangulation (calc_tangents aborts on any ngon), unit orthogonal tangent frames, bitangent == sign * (n x t), and mikktspace matching the independent edge/UV-delta formula on smooth fields. Documents the planar-on-cylinder UV degeneracy (tangent collapses onto the normal) and the stale layer-handle hazard that silently corrupts measurements on 4.5.
glTF skin round-trip: two orange-plated mech scorpions face off on a dark studio floor - the authored one on the left with its tail coiled over its back and claws tucked, the re-imported one on the right driven through its imported bones into a strike, tail reared high and claws raised

gltf-skin-roundtrip

The skinning counterpart to gltf-export-roundtrip: a 21-bone rigged mech scorpion exported with export_skins and re-imported, asserting the joint list, JOINTS_0/WEIGHTS_0 unit sums, bone/parent/rest-matrix round-trip, bit-exact weights, and identical deformation of the re-imported rig — plus the parenting hazard: unparented skinned meshes let the exporter bind an armature by name.
Collision hull proxy: a red fire hydrant street prop with a yellow bonnet on a dark studio floor, enclosed in four faceted translucent cyan collision shells - the compound convex hull set a game engine ingests

collision-hull-proxy

The compound-collision contract prop pipelines (engines generally, FiveM/GTA-style prop workflows specifically) ingest: one convex hull piece per part group, built with bmesh.ops.convex_hull from a coarse sec(π/n)-inflated cage — never the dense render mesh, whose hull measures 380 faces, over the 255-face per-piece engine budget. Closed-form plane tests prove containment (4.4e-08), convexity, watertightness, outward winding, and Euler characteristic 2 per piece. Proud details cost cage rows; concave grooves are free.
Custom normals and shade by angle: three olive-drab jerry cans with X-pressed panels, triple handles and red-sealed spouts on a dark studio floor - one faceted flat, one smeared glossy by smooth-everything, one crisp by-angle with its sharp edges traced in thin amber lines - proving the post-4.1 shading contract

custom-normals-shade

The shading contract a prop's silhouette depends on: since Blender 4.1, hard edges are mesh data (face smooth flags + sharp_edge attribute), and use_auto_smooth / use_custom_normals / calc_normals are AttributeError on both 4.5 LTS and 5.1. set_sharp_from_angle marks sharp exactly the edges an independent dihedral recompute predicts; evaluated loop normals weld across smooth edges and split by the dihedral across sharp ones; custom split normals survive depsgraph evaluation within their int16 quantization (3.904e-05, not float-exact). Documents the legacy shade_auto_smooth operator trap: CANCELLED headless on 4.5, FINISHED with the Smooth-by-Angle modifier on 5.1.
Mesh hygiene audit: two blue flanged street valves with brass handwheels — the left dirty copy with a red-outlined hole, a red flipped patch on the bonnet, an amber ngon on the base flange and three red loose-vert beads, the right one intact — proving the engine-ingest topology checklist

mesh-hygiene-audit

The mesh-cleanliness contract a prop pipeline relies on before engine ingest: no ngons, no loose vertices, every edge bordering exactly two faces, no zero-area faces, contiguous and outward winding on all eight parts of a flanged street valve, and Euler V − E + F == 2 on its body casting (measured 802/1632/832, volume 0.453344). Companion to collision-hull-proxy (hull watertightness) and bmesh-gear (parametric closed solids). Still: a dirty copy with a hole, flipped patch, ngon and loose verts marked from live audit data beside the intact valve; the paint glows red on any back face.
Prop origin transform: two green street utility pedestals, each centred in a floor pivot ring — left, the orange conduit elbow parented with matrix_parent_inverse stays bolted to its mount; right, bare child.parent = parent throws the elbow into the air beyond the slab while a glowing cyan outline marks its empty seat — proving scale apply, base origin, and matrix_parent_inverse

prop-origin-transform

The origin / scale-apply / MPI contract a prop pipeline relies on before engine ingest: data-API scale bake to exactly (1,1,1), local bbox min.z == 0 (origin at base), world AABB unchanged across the bake, and matrix_parent_inverse so a flanged conduit elbow stays on its mount. Extends parent-inverse-orrery without retreading orbits. Dual-panel still: TRAP (bare parent — empty socket + teleported flange) vs MPI KEEP.
Soccer ball Goldberg: a round white soccer ball with black pentagon panels and dark stitched seams around every hexagon, resting on mown pitch turf beside a chalked touchline — a bmesh icosphere truncated at one-third per edge into the Goldberg polyhedron, proving closed-form counts, uniform degree, equal edges, planar faces, one circumsphere, and panels bound by face vertex count

soccer-ball-goldberg

The truncated icosahedron as a bmesh contract: every icosphere edge cut at exactly 1/3, faces ordered by link-topology walks (nothing hand-listed), and every invariant asserted as a closed form — 60/90/32, Euler 2, uniform degree 3, edge lengths within 3e-5, planar faces against an independent Newell normal, one circumsphere, and the black pentagons / white hexagons bound by face vertex count, never enumeration order. Sibling to bmesh-gear (parametric extrusion): this one witnesses polyhedral invariants plus per-face-class material binding. The smoothed render inverts on sight if the panel binding does.
Car mirror symmetry: a smooth candy-red stylized hatchback on a dark studio floor, tinted glass, black pillars and arch cladding, a chrome window sill, silver five-spoke alloy wheels, and a matched headlamp and door-mirror pair either side of one centered grille — lofted as one half and completed by the Mirror modifier evaluated through the depsgraph, proving 2n-c counts, exact negated-X partners, a welded watertight centerline, and wheels mirrored about origins on the plane

car-mirror-symmetry

The Mirror + depsgraph contract: the datablock holds only the authored half (676/1289/614, 104 centerline verts) while the evaluated mesh is the welded whole — exactly 2n − c verts, watertight with Euler 2, every vertex paired at negated X (deviation 0.0). Wheels, lamps, grille, mirrors and handles mirror about object origins parked on the symmetry plane — offset the data, never the object. Companion to depsgraph-export (evaluated-vs- original) and shape-key-blend (non-destructive evaluation). Break the mirror and the render is literally half a car.
Attribute domain shear: two striped patio parasols on a terracotta paver deck behind slate placards — left CORNER-domain with crisp crimson and cream stripes, right naive POINT-domain with the stripes smeared pink along the seams and the front red panel gone white, proving last-write-wins shear at shared vertices

attribute-domain-shear

What POINT versus CORNER means on Mesh.color_attributes once a mesh has shared vertices. An eight-wedge pinwheel around one raised hub: CORNER authoring holds each wedge's exact color (hub corners disagree by face, err ≤ 1e-6), while the naive per-wedge POINT loop rewrites every shared vertex once per neighbor and the last write wins — the hub reads palette[K−1], and the measured shear matches the palette closed form (0.751031) exactly. Companion to color-attribute-wheel (domain sizing, active_color, the shader Attribute node). The render paints two striped parasols with the same authoring functions. The broken state is in frame: the right parasol's stripes smear along the seams and one crimson panel turns cream.
Degenerate bevel weld: two blue hard-shell equipment cases — left with a flat end panel and clean chamfer bands, right with its rim rolled into a knife ridge traced by a thin red-orange seam line and small amber pins at the zero-area faces, proving the half-dimension bevel collapse ships degenerate triangles

degenerate-bevel-weld

The half-dimension bevel collapse, isolated. A slab beveled at offset == min_dim/2 pinches its band into exactly 12 zero-area faces (4 min-axis edges × 3 segments) with 16 coincident verts and min_area down 3.2e5× — and a stdlib re-parse of the exported GLB counts 32 degenerate triangles shipped to disk, where an engine merge-by-distance welds their loops. Companion to gltf-export-roundtrip (where the count check first caught the weld) and mesh-hygiene-audit (topology gates). Seam markers are placed from live mesh data.
Modular kit snap: a corridor run of four tiling segments — dark steel walls with painted teal panels, diamond-plate walkways, hazard-striped orange trim rails, and ceiling light strips converging on a glowing amber doorway, with every joint seamless because the boundary verts snap exactly to the tile grid

modular-kit-snap

A tiling corridor kit where the snap is the contract. 16 boundary verts on x ∈ {0, 4} within 1e-6 m, opposing end loops coincident under the tile offset, and a linked duplicate's joint positions matching within 1e-6 — zero gap, zero overlap. Shell bbox equals the declared tile exactly, the tube is manifold except its two open ends, and all twelve detail parts are contained inside the tile. The unsnapped probe (3 mm skew) fails with the measured error printed. Companion to prop-origin-transform (pivot discipline) and mesh-hygiene-audit (topology gates).
Lightmap UV channel: a wooden market cart on spoked wheels with a cream canvas canopy beside a walnut-framed atlas display glowing with the bed's packed lightmap islands — proof the second UV layer packs with no overlaps, channel zero untouched

lightmap-uv-channel

The second UV layer engines need for baked lighting, on a reusable market cart. Per-part UVMap/UVLight with active vs active_render pinned (the edit-mode UV ops clear both flags — re-assert or lose them), channel zero untouched by the second unwrap (drift 0.0, the clobber probe measures 2.068), every island inside [0,1], 0 overlapping islands by an independent SAT scan, and a measured min island distance of 0.00401 against the stated margin. Companion to uv-layer-grid (UV authoring) and triangulate-tangents (tangents from UVs).
Socket attach points: a cobalt-and-graphite survey quadcopter with carbon-weave arms hovering over a studio stage, orange mount pads ringing each canted rotor, a gimbal camera pod under the belly and a sensor mast on the deck — every module seated exactly on its named socket

socket-attach-points

Named SKT_ empties as the spawn contract, on a reusable survey drone. All 7 socket world matrices land within 1.788e-07 of the authored transform with orthonormal right-handed bases, each socket's +Z equals its mount pad's Newell normal (1.794e-07) by a derivation independent of the basis construction, and modules seat at offset exactly 0.0 with identity local transforms. Freezing the root preserves world matrices but clears 7/7 parent-inverses and pushes the root scale into the children — both halves asserted. The no-parent-inverse probe jumps 0.690128 m. Companion to prop-origin-transform (pivot discipline) and parent-inverse-orrery (parent-inverse under animation).
Vertex colour AO: a stone village well of chamfered, irregular blocks on a dark studio stage, its V-groove masonry joints, shaft mouth and coping undersides darkened by ambient occlusion baked into a colour attribute rather than by the lights

vertex-color-ao

Baked occlusion in a colour attribute, checked against a formula instead of a captured value: the cosine-weighted hemisphere integral for a wall of height H at distance d is 1 - ½(1 - 1/√(1+k²)), k = H/d, and the integrator matches it to 6.760e-04 across two decades of k. An unoccluded plate bakes to exactly 1.0. FLOAT_COLOR round-trips exactly while BYTE_COLOR is sRGB-encoded 8-bit — 0.735 reads back 0.7379107, matching an independent encode/quantise/decode model to 3.189e-07. Both survive depsgraph evaluation at deviation 0.0. Companion to color-attribute-wheel and attribute-domain-shear.
check-only, no gallery still — a hexagon on a cube is not thumbnail-legible

ngon-triangulate

Synthesizes one 6-loop hexagon by dissolving a cube edge. Pre-asserts the n-gon exists (1 face / 6 loops / 5 faces), then calc_tangents aborts until bmesh.ops.triangulate yields 4 tris + 4 quads / 28 loops. glTF tri count is 12 either way. Inverse of mesh-hygiene-audit.
check-only, no gallery still — unapplied scale looks like modeled non-uniform size

unapplied-scale-gltf

Unit cube with object scale (2, 1, 0.5). Pre-asserts unapplied non-uniform scale and local ±1 verts, then glTF export_apply=True still writes Y-up node.scale (2, 0.5, 1) with local POSITION. export_apply is modifiers only. Inverse of gltf-export-roundtrip.
check-only, no gallery still — coincident cubes look like one cube

coincident-vert-weld

Two cubes in one mesh: 16 verts / 8 unique / still manifold. Pre-asserts the duplicates, then glTF ships 24 tris / 48 positions / 8 unique. remove_doubles collapses to one cube. Inverse of degenerate-bevel-weld.

How content is organized

skills/<name>/SKILL.md   - 16 skill files, YAML frontmatter, one canonical pattern each
rules/<name>.mdc         - 9 rule files, anti-pattern + correction
templates/<name>/        - 3 template directories (extension-addon-template, headless-batch-script-template, ai-asset-pipeline-template)
snippets/<name>.py       - 27 standalone Python snippets, 5 to 50 lines each

Using rules in Cursor

The .mdc files in rules/ apply automatically when Cursor opens a Blender Python project, scoped by the globs in each rule's frontmatter. The nine rules are:

  • prefer-data-over-ops-in-loops: flags bpy.ops.* calls inside object iteration
  • always-free-bmesh: flags bmesh.new() without paired bm.free() in try/finally
  • target-extensions-platform-format: flags add-ons missing blender_manifest.toml
  • type-annotate-props-and-defend-context: flags bpy.props assignment form and unguarded context.active_object
  • prefer-temp-override-over-context-copy: flags bpy.context.copy() passed to operators (deprecated 4.x, removed 5.x)
  • use-foreach-set-for-bulk-data: flags Python loops over mesh.vertices setting co, normals, or other per-element bulk data
  • validate-imported-mesh-scale: flags glTF/FBX import then mesh work with no transform_apply and no unit-scale check
  • no-unapplied-modifiers-on-export: flags export of objects with live modifiers when the export does not request evaluated geometry
  • use-correct-axis-rna-per-exporter: flags export_scene.gltf calls that pass FBX axis_forward / axis_up, and export_scene.fbx calls that pass glTF export_yup

Symlink or clone this repo, then point Cursor at it as a skills/rules source.

Using the templates

templates/extension-addon-template/ is a working Blender extension. Copy the directory, edit blender_manifest.toml (id, version, name, maintainer), and install via Edit > Preferences > Get Extensions > Install From Disk. The template registers an Operator, a Panel, and a PropertyGroup, and demonstrates the register_classes_factory pattern with symmetric register() and unregister().

templates/headless-batch-script-template/ is a working starter for unattended Blender batch jobs. It opens a .blend, optionally adds and applies a modifier to every mesh, and exports to glTF, with explicit exit codes for CI integration. Run with blender --background <input.blend> --python script.py -- --output ....

templates/ai-asset-pipeline-template/ is a working starter for a headless GLB-in / engine-ready-out job. It imports a GLB, runs the ai-mesh-cleanup order, emits an LOD chain and optional collider, and exports under a Unity, Godot, or Unreal glTF preset. Run with blender --background --python pipeline.py -- --input ... --outdir ... --preset unity.

Snippets

Each snippet is a standalone Python file under snippets/. They are not loaded as a package. Open one, copy the relevant lines into your script, and adapt the names. Each file's header comment cites the Blender doc URL or research section the pattern came from.

Canonical references

Resource Use it for
Blender 5.2 LTS Python API Authoritative reference for current stable APIs
Blender 5.1 Python API Prior stable
Blender 4.5 LTS Python API LTS reference when targeting 4.5
Extensions Platform manual blender_manifest.toml schema, hosting, install flow
developer.blender.org Release notes, breaking change tracking, design docs

When community content (Stack Overflow, older add-on source) conflicts with the official docs, prefer the docs. The 2.x to 4.x to 5.x churn around Actions, Extensions, and property handling has invalidated a lot of older material.

Roadmap

See ROADMAP.md for the candidate pool and what ships next. Releases are cut automatically from conventional commits; the full history lives in CHANGELOG.md.

Contributing

Issues and pull requests are welcome — see CONTRIBUTING.md for the workflow, SECURITY.md for reporting vulnerabilities, and CODE_OF_CONDUCT.md for community standards. New examples must follow the anatomy of examples/bmesh-gear/ and the render look in docs/VISUAL-STYLE.md.

License

Copyright (c) 2026 TM Hospitality Strategies. Licensed under CC-BY-NC-ND-4.0.