System Information
win7 64 k2200
Blender Version
Broken: 2.78a
Worked: 2.76
Short description of error
export OBJ corrupt a little bit the uv, no problem with FBX.
Exact steps for others to reproduce the error
open the file, export the monkey in obj format, import again in blender and compare the uvs (by merging the two objects). you can notice a slight difference.
thankyou!
| rBA Blender Add-ons | |||
| rBAafde50f68185 Fix T49865: export .obj broke UVs. | |||
Thanks for the report, but that’s not really a bug here, issue is, OBJ being a pure textual format, we have to round float numbers (to the forth decimal currently) to avoid generating insanely big files. This of course involves a small loss of data - that’s why binary formats (like FBX) should be used when in need of full float precision.
Thanks for the reply,
But objects exported with Blender 2.77 or 2.76 doesn't give me the same error.
can you please take a look into it.
thanks again.
I copied the 'io_scene_obj' folder from 2.77 and pasted in 2,78, now Blender export the uvs correctly.
I compared the 2 codes and I see some differences on line 575 and 546
Blender 2.77
fw('vt %.6f %.6f\n' % uv[:])
Blender 2.78
fw('vt %.4f %.4f\n' % uv[:])
thankyou
Changes comes from rBA887fad6a0196be (fixing T39879).
That’s the usual trade-of of float precision here actually, too much precision might make UV points actually merged look like split (due to errors introduced during float computation), too low precision will reduce exactness…
Fixing T39879 could also be done by using a 'limited-precision comparison' instead of exact comparison, afraid it will makes things slower though… Will investigate further.
Uh, actually, was wrong it’s rBAc553d7c0eb002 the culprit here… Not totally sure why precision was reduced here, so will restore it back to 6 decimals for now.