Art-Asset Forge Pipeline

The whole road a line of text travels to become a textured, rigged, animated, equippable model — in the order it runs, with the real tool that runs each stage. A character is never one baked mesh: it's a recipe the engine assembles from a base body + composable parts + a material preset + slotted equipment, all on the shared 19-bone runtime rig.

concept driver→ forge · TRELLIS.2 1024³ · PBR→ bake + decimate→ skin · 19-bone rig→ equip→ in-engine

Two lanes — mechanical vs organic

The forge, bake and decimate stages are shared. The pipeline forks only at the end, in how the finished mesh attaches to the skeleton.

Mechanical — rigid plate mount

A machine can't skin: a metal plate bent across a joint tears. So a mech / power-armor suit is composed rigid-per-part — each plate bound to one bone (a dark collar + hinge-stub closes the joint, the Iron-Man trick) so armour rotates but never stretches. Raw parts self-intersect, so they're cut at the joints, fused + remeshed into a watertight shell, then recolored per-unit. One shared walker skeleton drives the whole roster.

Organic — skinned + cloth deform

Flesh and fabric do bend, so organic parts are skinned to the skeleton instead of mounted. Fitted garments track the torso; loose garments ride a sway chain so they drape and swing. Hair splits both ways — caps mount rigidly, long hair is skinned.

Three deform tiers

Every finished part lands in exactly one tier. The tier decides which skinning tool runs and how the part attaches at runtime.

Tier	For	Forged by	Runtime attach
rigid mount	mech plates, armour, eyewear, jewelry, gadgets, weapons	`blender_skin_armor.py` (fitted) · rigid compose (plates)	rigid BoneAttachment — bound to one bone (`neural_gear.gd`)
skinned	shirt, vest, undersuit, boots, long hair, species tails	`blender_skin_armor.py` · `blender_skin_hair.py`	skinned sibling — weighted to the shared skeleton, deforms with the body
loose cloth	greatcoat, cape, skirt, reptilian tail	`blender_skin_cloth.py` — own `cloth_0..N` chain, skinned by height	cloth sibling — damped sway chain, `cloth_sway.gd` (`ClothSway`)

Rigid never stretches; skinned bends with the joints; loose cloth lags-and-settles like a real garment. ClothSway is deliberately not a cloth solver — one cheap damped follow per bone (a spring back to rest, kicked by body velocity), an order of magnitude cheaper than PBD/XPBD and good enough to sell "cloth".

The pipeline, stage by stage

Concept driver — txt2img

A text description becomes one clean driving image, leveraging every txt2img tool best-per-subject: agy (OAuth Pro, no cost) for the final clean driver; FLUX, SD3.5 and SDXL for fast local exploration. Only one image feeds the forge; cached <slug>_fullbody.png drivers are reused, never regenerated.

Single subject, plain background, A/T-pose — no weapons/props. A posed hero shot bakes the pose in and won't rig; keep it for marketing, forge from a clean A-pose.
Base body — no baked clothing. A tight base layer only; coats/armour are added later as separate rigged pieces, never baked in (a loose garment baked into the mesh tears on animation).

tools: agy_character.sh · flux_fullbody.py · sd_fullbody.py · sd_ipadapter.py · gate: single_subject_check.py

Forge — TRELLIS.2-4B @ 1024³, full PBR

The driver becomes a high-detail textured mesh: shape at grid 1024 (dual-contouring 512) with the full PBR set baked into a UV atlas — base-color, metallic, roughness, opacity. Output is a ~150k-face hero mesh: real materials, but no normal map and far too heavy for gameplay (stage 3 fixes both).

tools: trellis2_gen.py · forge_one.sh (characters) · forge_garment_trellis.py (apparel) · reforge_*.sh (batch)

Bake + decimate — tangent normal, poly budget

Decimate-COLLAPSE the hero mesh to a per-type game poly budget — collapse interpolates the existing UVs, so the baked PBR still maps correctly (no re-bake). Then bake a tangent-space normal map from the hi mesh onto the decimated mesh (Cycles selected-to-active), carrying the detail the decimation drops, and wire it into the game material. Result: a game-budget mesh with base-color + metallic + roughness + opacity + normal.

tool: bake_decimate_normal.py — the "1024³ → bake FULL PBR → decimate to budget" standard

Skin / retarget — the 19-bone runtime rig

The game mesh is bound to the shared 19-bone skeleton so it can animate. The tool depends on the deform tier: fitted parts → blender_skin_armor.py; hair → blender_skin_hair.py (caps mount rigidly, long hair skins); loose cloth → blender_skin_cloth.py, which builds the garment its own cloth_0..N mid-line chain and skins it by height so it drapes as one sheet (never split L/R onto the thigh bones). Characters and mechs share the skeleton — which is why one baked walk clip drives the whole roster.

tools: blender_skin_armor.py · blender_skin_hair.py · blender_skin_cloth.py · libraries: apparel_library.py, hair_library.py

Equip — attach the part to a body

The finished part is attached in one of three ways, matching its tier. Rigid BoneAttachment — hard gear bound to one mount bone; NeuralGear auto-calibrates seats per body and exposes mounts (head, face, shoulder_l/r, back, hip_l/r, chest, foot_l/r, neck, wrist_l/r). Skinned sibling — a fitted garment added as a second skinned mesh sharing the skeleton. Cloth sibling — a loose garment mounted by ClothSway.attach_cloth, re-rooting its cloth_0 onto the torso and installing the self-driving sway.

tools: neural_gear.gd (rigid + skinned) · cloth_sway.gd (loose)

In-engine

The composed character is live in gameplay: neural_gear.gd composes the rigid + skinned parts (with per-faction kit accents from content/faction_styles.json), and onfoot.gd is the on-foot controller that walks and animates the assembled body. Assembled at load time from the recipe — base body + parts + material + equipment — never a single baked glb.

tools: neural_gear.gd · onfoot.gd

Model Showcase — concept vs composed ▶ Composition Lab — live viewers ▶ Motion Lab — every clip live ▶ Golden-body fidelity pipeline ▶

Art-Asset Forge Pipeline · concept driver → forge (TRELLIS.2-4B, 1024³, full PBR) → bake + decimate → skin to the 19-bone rig → equip → in-engine · mechanical (rigid) vs organic (skinned + cloth) · three deform tiers. Full write-up with per-stage file list: docs/art-asset-forge/pipeline.md.