* Polyface meshes stay one object through DXF and DWG
A polyface mesh (POLYLINE flag 64) was read as loose 3D faces. It is now
read, drawn, exploded into its 3D faces and written back as a POLYLINE.
Hidden edges aren't drawn. A mesh too large for the 16-bit groups 71-74
is saved as 3D faces.
Split from #1005.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
* A polyface face ends at its first zero index
A face record with a gap ([1, 2, 0, 3]) has two corners and is dropped,
not read as a triangle.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
* Polyface meshes: write only faces that name their vertices; ID gives their Z
The writer drops the faces the reader would drop, so no record names a
missing vertex, and the 16-bit check only needs the counts. ID and DIST
give a mesh the Z of its nearest visible edge, as they do for 3D faces.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>
