Stage containers (hidden/resource3d/Stage_S*.xpr) are collections of up to
~450 enemy/prop sub-models, not single meshes. Xbg7Model::stage_models decodes
them: each resource is a [12-byte header][index buffer][vertex buffer] block
(index count = descriptor marker, vertex count = u32 32 bytes before it) whose
on-disc offset is NOT stored, so it is located by content — one O(file) pass per
stride finds vertex-buffer starts (unit NORMAL at +12 whose previous slot isn't)
and each resource is pinned to the candidate whose indices validate and produce
non-degenerate, well-connected triangles. A connectivity gate (mean triangle
edge <= 0.28x the bbox diagonal) rejects spiky mis-anchors. ~4993 sub-models
decode across the 22 stages.
The same insight fixes the weapon single-model layout: it is [12-byte header]
[index][vertex] too, not [index][12-byte gap][vertex]. Reading indices from the
block start turned the 12 header bytes into 6 junk indices (2 leading degenerate
triangles — the recurring stray-triangle artifact) and dropped the last 6 real
indices. Skipping the header leaves vertex offsets identical (coverage unchanged
at 36/166) and corrects the triangle list. Verified on wep_00/03/04.
Adds `sylpheed-cli mesh {info,render}` — a headless software rasterizer that
writes a shaded PNG (orthographic, z-buffered, two-sided), so recovered geometry
can be verified without the GUI. Stages render as a normalised thumbnail grid;
--only filters sub-models.
Tests: stage_models_{decode,sweep,quality_audit}; docs/re updated (xbg7-mesh.md
evidence log + INDEX.md).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2053f31d17