nx_nxa_texc_lib.nx

nx_nxa_texc_lib.nx -- ★TEXC: UV TEXTURE COORDINATES AS A FORMAT CAPABILITY (debt 1785794796 rung 1). The measured fact that forced this: ref9.nxa declares VERT TRIS CLUS SKEL SKIN ANIM HSTR GVRT GTRI GPIN POSE -- NO TEXC, NO UV -- so sampling ANY texture map was IMPOSSIBLE, and 'we shade procedurally from genome' was a CONSTRAINT wearing the costume of a choice. This lib computes a bone-anchored cylindrical unwrap from sections the asset ALREADY carries (SKEL world bind positions + SKIN top-4 weights) and writes a TEXC section: every vertex gets a stable atlas coordinate AND a region tag. UNWRAP (integer, deterministic): per vertex take its PRIMARY bone (max SKIN weight slot). v = clamped position along the parent->joint bind segment (Q12 -> Q16). u = angle around the bone's DOMINANT axis (rt_atan2, full circle 25736 it-units -> Q16). Each joint owns one TILE of a g x g atlas grid (g = ceil(sqrt(nj))), so charts from different bones are DISJOINT BY CONSTRUCTION -- a bake and a sampler sharing this section can never bleed one body part into another. Seams sit at weight boundaries (rigid ownership); bake+sample use the SAME mapping so sampling stays self-consistent. TEXC payload (i64 words): [0]=nv [1]=stride(3) [2]=atlas grid g [3]=reserved(0), then per vertex: [u q16 0..65535][v q16 0..65535][owning joint]. The joint word IS the region tag (rung 2 seed): finer than Face|Torso|Limbs and groupable through SKEL parents later. ADDITIVE AND IDEMPOTENT like its siblings (nx_nxa_dyna): the input is never modified; an existing TEXC is REPLACED, so running twice is identical to running once. FAIL-CLOSED: refuses with a NAMED reason rather than fabricate (no SKIN -> no invented ownership; count mismatch -> refuse). license_tier: ORIGINAL No hw writes (Rule 26).