40 lines
4.6 KiB
Markdown
40 lines
4.6 KiB
Markdown
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# Brief: Blender-only garment pipeline for ariki-game — request for review
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You are being asked to review a technical plan and give advice: identify risks, suggest better techniques, and flag anything missing. Be concrete and critical. You have no file access — everything you need is in this brief.
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## Context
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- Godot 4.7 game. All characters share one 65-bone skeleton ("Quaternius", UE-style bone names, T-pose rest). Runtime clothing system stacks garment GLBs onto the character's Skeleton3D by bone-name binding — this works and ships.
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- Hero character "Lena": a Tripo photo-scan mesh (25.7k tris, baked albedo texture), rigged to the shared skeleton. She is the fit target. Her body mesh + full vertex-group weights are available in Blender.
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- Existing tooling (headless Blender 5.1, Python): GLB/FBX import; KDTree nearest-vertex weight-copy from body→garment (proven on prior outfit sets); a skeleton-anchored alignment tool (scales/positions a garment onto the body by hip/head/arm frame); collapse-decimation with per-part tri budget (~1,500 tris/part); glTF export. Deterministic, scriptable, no GUI.
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- We deliberately rejected Character Creator 5 for clothing: our characters are AccuRig "Humanoid" avatars, and CC5 provably refuses conform/Transfer-Skin-Weights on Humanoids (verified via its Python API and GUI this week). CC5's conform also only fits its own proxy bodies, so a Blender fit pass to the real mesh is needed regardless.
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## The garment to process
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A Marvelous Designer FBX export ("thin, unwelded"): ONE mesh, 2.49M verts / 4.30M tris, human-scale (zmin 0.59m, zmax 1.65m), 12 materials that partition it into logical parts: cropped jacket (sleeved), shirt-dress bodice, pleated knee-length skirt, bow belt, second cloth layers. No textures (flat MD material colors), single UV map. Modeled in a slightly arms-down pose (not T-pose).
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## The plan (v1 scope: bodice + skirt + bow; jacket with sleeves deferred)
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1. Split the mesh by material into parts; group into Body-slot (bodice+bow) and Legs-slot (skirt).
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2. Per part: merge-by-distance weld (it's unwelded MD output), then collapse-decimate to ≤1,500 tris. Keep the UV map.
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3. Align the garment set onto Lena's body (uniform scale + translation; both are upright human-scale so a bbox/landmark alignment suffices).
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4. Fit pass: Shrinkwrap (nearest-surface, ~6-8mm offset) masked by a vertex group — full influence on the snug bodice, fading to zero influence a little below the hip so the skirt keeps its hanging silhouette and only the waistband conforms.
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5. Weight transfer: KDTree nearest-body-vertex copy from Lena's weighted body mesh to each garment part. Known weak point: the skirt — nearest-vertex copy gives hard left/right leg weights near the hem, causing tearing/stretching in walk cycles. Planned mitigation v1: below-crotch vertices get blended thigh weights or pelvis-dominant weights (accept reduced skirt motion); skirt bones + jiggle are a later upgrade, not v1.
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6. Export per-part GLBs bound to the shared skeleton; register in the game's outfit catalog; verify in the in-game clothing test bed (idle, walk, dance).
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## Constraints
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- End result must be statically skinned (no runtime cloth sim; Godot, crowd-scale).
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- Tri budget ~1,500/part. One material per part preferred; flat colors acceptable for now.
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- Everything must run headless/scripted (agent-driven pipeline, repeatable for future garments).
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- The body stays under the garment (no body-hide system yet) — clearance must prevent poke-through across the animation set.
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## Questions for you
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1. Weld+decimate 4.3M→1.5k is a ~3000× reduction on unwelded MD triangle soup. Better approach than collapse-decimate? (e.g., voxel remesh then decimate; shrinkwrap a low-poly proxy onto the high-poly; MD's own quad-remesh if we re-export?) What preserves pleats/silhouette best at 1.5k tris?
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2. Best practice for the skirt weights on a humanoid rig without extra bones — is there a standard "skirt weighting" recipe (e.g., project weights from a cylinder, distance-weighted thigh blend, pelvis-locked hem)?
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3. Any pitfalls with shrinkwrap-fitting a multi-layer outfit (bodice over body, bow over bodice) — how to keep layer separation at low poly counts?
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4. The garment is in a slightly arms-down pose while the target binds in T-pose; v1 avoids sleeves entirely. For v2 (jacket), what's the cleanest scripted approach to re-pose garment sleeves to T before fitting?
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5. UVs and baked detail: at 1.5k tris the pleats will flatten. Is baking the high-poly's normals/AO onto the low-poly worth it in this budget, and any workflow notes for MD unwelded sources (UV islands per panel)?
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6. Anything in this plan you would do differently overall?
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