3mf files with identical model contents are not binary identical. #31
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Description
Added 3mf support to https://github.com/deadsy/sdfx.
It looks like the compression process is adding some per-run data. It doesn't look like a timestamp.
Not a show-stopper but having the same input give the same output is a nice regression property.
ie - we test the sha1sum of the output. This works for an STL, but not for a 3MF.
I guess the issue is possibly fixable in qmuntal/opc or maybe compress/flate, but I mention it here.
> sha1sum *3mf
c28eed4f13d0c62b0b7d57017d32427bbbea8206 head1.3mf
481ccd135a874c9690d92a99b90b67816e54340b head2.3mf
> unzip -v head1.3mf
Archive: head1.3mf
Length Method Size Cmpr Date Time CRC-32 Name
-------- ------ ------- ---- ---------- ----- -------- ----
29548892 Defl:N 3507185 88% 2022-09-30 09:18 9bfc8b92 3D/3dmodel.model
279 Defl:N 190 32% 2022-09-30 09:18 4c62f2b8 _rels/.rels
347 Defl:N 208 40% 2022-09-30 09:18 9dd59dad [Content_Types].xml
-------- ------- --- -------
29549518 3507583 88% 3 files
> unzip -v head2.3mf
Archive: head2.3mf
Length Method Size Cmpr Date Time CRC-32 Name
-------- ------ ------- ---- ---------- ----- -------- ----
29548892 Defl:N 3507185 88% 2022-09-30 09:18 9bfc8b92 3D/3dmodel.model
279 Defl:N 190 32% 2022-09-30 09:18 4c62f2b8 _rels/.rels
347 Defl:N 208 40% 2022-09-30 09:18 9dd59dad [Content_Types].xml
-------- ------- --- -------
29549518 3507583 88% 3 files
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