OBJ import discards unique faces, 3DS to lesser extent #57965
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Reference: blender/blender-addons#57965
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Blender Version
2.76
Short description of error
The OBJ import script destructively remaps face indices, somehow that is not obvious. This deforms/discards faces that have vertices with identical locations but different surface normals, texture coordinates, etc. This is a very ill conceived script for such a mature tool as Blender. Can it please be updated?
https://blenderartists.org/t/obj-import-problem-double-sided-polygons-that-share-vertices/655668/2
The 3DS script occasionally deletes faces, but it is not obvious why it does so. The OBJ script will always delete a face if it's identical to another face, with different normals. The 3DS script will do this for about 5% of the same faces. Maybe if you are lucky, the mesh remains intact.
This is, needless to say, comical, and unacceptable. I have a lot of experience with programming import/export routines in C++. But I don't think I can help here, and have no Python experience. The faces are deleted without the split option. I don't think that's the root of the problem. But it looks like the splitting is copying vertex position data, which doesn't make any sense in that context: verts_split.append(verts_loc[i])
P.S. I would like to add Tags, but it seems not possible. Thanks!
Added subscriber: @Mick-P-2
blender/blender#87580 was marked as duplicate of this issue
Added subscriber: @mont29
Changed status from 'Open' to: 'Archived'
OBJ script does not allow to import corrupted geometry in Blender, and tries to its best to fix those cases. No bug here, that is intended, sane behavior.
Changed status from 'Archived' to: 'Open'
@mont29 Typical do-nothing free-software hacks response.
There's nothing corrupt about triangles that share attributes. It's common practice for triangles to have two sides, which is absolutely not supported.
What gives anyone the sense they can Close a ticket without any single interaction?
Added subscriber: @pablovazquez
Not my area but that discussion is from 2015, and your Blender Version says "2.76" which is over 3 years old.
You should always test with the latest stable release from https://www.blender.org/download/ . And even if possible with a development version in case it has been fixed already since the last release.
Removed subscriber: @pablovazquez
Changed status from 'Open' to: 'Archived'
Added subscriber: @pablovazquez
@pablovazquez here, version does not really matters, this is a global Blender behavior.
@Mick-P-2 Next time I’d appreciate you know what you are talking about before saying that kind of things (and re-opening tasks). Two faces using same triangle might be valid "common" case in some applications, but in Blender this is considered invalid geometry, and can break a lot of tools, render, etc.
Last instruction will give you following error in the console:
And btw, this is not a support tracker, this is a bug tracker. No bug = ticket closed.
Changed status from 'Archived' to: 'Open'
Seriously fuck off @mont29. You're not helping anything. I'm tired of running into people like you in free-software trackers. Do you work for Autodesk?
Here is an OBJ that completely removes geometry for no reason from this model that should be a cat's eye shape in the center of the outer sphere. I can't find an an attachment function, so I'm inlining the file. The top and bottom is sliced off by the OBJ importer.
@pablovazquez I understand, but I couldn't find an Issue in the tracker on this subject, so I presume it's unaddressed. I would like to see the change logs or commits on this script file, if I knew where to look for it I would have done that first. It can't hurt to have a record in the tracker though.
Changed status from 'Open' to: 'Archived'
Added subscriber: @brecht
@Mick-P-2, we expect a minimum of professional behavior when interacting in this bug tracker. You might disagree, but in the end it's up to developers to decide what is considered a bug, and we absolutely do not accept personal attacks like this.
@Mick-P-2 next time your account will be disabled, handling a bug tracker is hard and time-consuming enough, not to have to deal with that kind of behavior in addition.
@brecht Tell that to @mont29... Who could not be less professional/more toxic to software development.
Added subscribers: @MadFaTal, @ankitm