# W-076 Status

status: in_progress  
task: 属性、UV 和蒙皮安全简化

`SimplifyProfile` now requires an explicit attribute policy after parsing and
defines `SkinSimplifyPolicy` limits for influences, weights, position error and
shape keys. The native command currently implements this partial protection
matrix:

- normals are recomputed from the evaluated triangle topology;
- BMFace material indices and material slot IDs are retained;
- existing UV and float-color corner values are transferred to output corners
  using a deterministic closest-source-triangle barycentric projection;
- `DROP` is the only policy that removes these arrays intentionally;
- Collapse validates and accepts open/non-manifold Mesh-to-BMesh topology;
- the native reader exports Mesh `MDeformVert` CustomData as fixed four-slot
  `SkinWeightsIR` arrays, carries Mesh vertex-group names, and exports
  non-Basis `KeyBlock` positions as `ShapeKeyIR`; the local
  `rigged_shape_scene.blend` fixture validates both on a real `.blend` file;
- a skinned or shape-key mesh requires explicit `skinPolicy`; omitting it is a
  structured `NOT_IMPLEMENTED` failure rather than silent attribute loss.

Native smoke and browser Worker E2E verify normal, UV, corner and material
buffer sizes on the closed cube fixture. The WebEngine protocol validates
`SkinWeightsIR` and `ShapeKeyIR`. After BMesh produces the authoritative
topology, native code projects each output vertex onto the closest source
triangle, merges and normalizes its joint influences, and reconstructs every
shape-key position with the same barycentric weights. `maxInfluences`,
`minWeight` and `maxPositionError` are enforced before committing the new
SceneIR. Native smoke and Worker E2E verify output vertex counts, normalized
weights, stable joint IDs, bind matrices and shape-key array lengths.
`shapeKeys: REJECT` still returns `SHAPE_KEYS_REJECTED` before native work.

The reader now exports `ArmatureIR` bones with parent IDs, Blender `Bone.arm_mat`
rest matrices and matching `PoseChannel.pose_mat` matrices. A mesh Armature
modifier resolves its armature object, remaps vertex-group bone names to stable
joint IDs, and records the mesh object TRS as its non-identity bind matrix. The
generated rig fixture verifies all fields against local Blender data. This is
sufficient for GLB inverse-bind generation and the current triangle-bridge
remapping path.

UV seam and sharp-edge error metrics, tangent regeneration, native
vertex-group name selection in profiles, Armature deformation comparison,
seam/sharp constraints and Blender-evaluated shape-key error comparison remain
required before this task can be marked done.