nx_vmd.nx

nx_vmd.nx -- VMD (Vocaloid Motion Data) MOTION DECODER: the MMD dance corpus, read sovereignly. WHY THIS EXISTS (measured 2026-08-07 against vrstormlab.com/dancexr/play, from their own served bytes -- not their marketing copy): the free LW build ingests PMX + XPS models and VMD + BVH motion. Our estate already owns the OTHER half of that pipeline -- nx_pose_retarget inverts the sovereign FK, nx_gltf2mesh segments a donor into 74 named parts -- and owned ZERO of their four ingest formats. A grep for "bvh" found nx_bvh and read as a match; nx_bvh is a BOUNDING VOLUME HIERARCHY for the slicer, not BioVision Hierarchy motion capture. *A NAME IS NOT A CAPABILITY. A GREP FINDS THE CLAIM; ONLY READING THE SOURCE SETTLES IT. VMD is the keystone of the four because the dance corpus is overwhelmingly VMD, and because it carries exactly what our retarget consumes: per-bone, per-frame rotations on a named skeleton. FAIL-CLOSED BY CONSTRUCTION: every field is bounds-checked against the ACTUAL file length before it is read. A count in a header is a CLAIM, never an authority. A truncated file is REFUSED, not partially parsed into a plausible-looking track -- because a plausible segmentation is the most dangerous kind, and a motion track that silently stops at frame 40 of 400 still animates. UNITS ARE DECLARED, NEVER IMPLIED (a threshold is meaningless until its unit is stated): positions = VMD/MMD model units x V_SCALE_POS (1000). NOT millimetres; MMD units are their own. rotations = quaternion components x V_SCALE_ROT (4096), each in [-4096, 4096]. morph = weight x V_SCALE_POS (1000), nominally [0, 1000]. usage: nx_vmd info <file.vmd> version, model name, per-section counts, duration in frames nx_vmd bones <file.vmd> per-bone keyframe census (raw name bytes + id) nx_vmd dump <file.vmd> [n] first n bone keyframes as rows nx_vmd --kat selftest: 7 teeth, 4 of them anti-vacuity exit 0 ok | 2 unreadable | 3 usage | 4 REFUSED (bad magic / truncated / count exceeds bytes) | 1 selftest RED license_tier: ORIGINAL No hw writes (Rule 26). expect_exit: 0