compute_world_offset rejected any entity whose owner_handle didn't
equal model_block, but belongs_to_visible_block (the render-time
filter) treats owner_handle = null as a legitimate MSPACE entity
whenever block_record.entity_handles is empty and the file enumerates
no block contents anywhere. DXF writers commonly omit group-code 330,
so on those files the render path drew the entities while the offset
scan missed them — direct WCS-coordinate wires then drove world_offset
to the header (sentinel → [0,0,0]) and f32 precision collapsed for
UTM-authored content.
Replicate belongs_to_visible_block's decision exactly:
* If model_block's BlockRecord enumerates entity_handles, use that
set as the authoritative MSPACE membership list.
* Otherwise: owner==model_block always counts; owner==null counts
only when no other block_record enumerated either (legacy DXF
without 330 codes anywhere); a non-null owner pointing elsewhere
or an entity enumerated by some other block is always rejected.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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