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Re: Bug or refactoring artifact?
by bART Janssens-2
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On Wed, Jun 24, 2009 at 4:42 AM, Timothy M. Shead<tshead@...> wrote:
>> Daniel Scott Matthews wrote:
>>> I am seeing this on the console when importing with both the OBJ and
>>> the 3DS mesh readers.
>>>
>>> ERROR: /home/daniel/projects/k3d/k3dsdk/normal3.h line 207: assertion
>>> `length' failed
>>
>> This message indicates that we're trying to normalize a zero-length
>> normal vector, which would cause a divide-by-zero error if we didn't
>> catch it. Could you send a small sample OBJ that causes this message?
>
> After loading a modest example sent by Daniel, I'm able to reproduce this.
> After putting an assert() in k3dsdk/normal3.h, I can see that this
> computation is happening in the painter cache code, so I'm going to hand
> this off to Bart ...Well, I've traced back the problem to two bad faces in the source
mesh. The faces appear to be reduced to a single point, so no normal
can be calculated. The first attached image shows these faces moved up
5m.
The missing wheels are a mystery to me, but this happens in both K-3D
and XSI Mod Tool. This is
unrelated to the normals error. Are you sure everything was exported properly?
In order to select and move the bad faces, I made the following changes in SVN:
- Made normals_cache print the index of bad faces
- Added a FaceToPointSelections plugin, to convert face selections to points
- Fixed a bug with mesh_simple_deformation_modifier that prevented
selection from working correctly
You should now be able to use the following procedure to identify or
fix bad faces:
- Look in the debug output for the bad face numbers
- Select a bad face using SelectFaceByNumber
- Convert this selection to points using FaceToPointSelections
- Apply a modifier, i.e. TranslatePoints or JoinPoints (needs to be
restored to the new mesh format)
- Click the "Clear" button on this modifiers mesh_selection property,
so only the points belonging to the bad face get affected
The real solution for this would be a plugin that helps cleaning up
meshes and does things like removing faces smaller than a threshold.
Cheers,
--
Bart
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K3d-development mailing list
K3d-development@...
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>> Daniel Scott Matthews wrote:
>>> I am seeing this on the console when importing with both the OBJ and
>>> the 3DS mesh readers.
>>>
>>> ERROR: /home/daniel/projects/k3d/k3dsdk/normal3.h line 207: assertion
>>> `length' failed
>>
>> This message indicates that we're trying to normalize a zero-length
>> normal vector, which would cause a divide-by-zero error if we didn't
>> catch it. Could you send a small sample OBJ that causes this message?
>
> After loading a modest example sent by Daniel, I'm able to reproduce this.
> After putting an assert() in k3dsdk/normal3.h, I can see that this
> computation is happening in the painter cache code, so I'm going to hand
> this off to Bart ...
mesh. The faces appear to be reduced to a single point, so no normal
can be calculated. The first attached image shows these faces moved up
5m.
The missing wheels are a mystery to me, but this happens in both K-3D
and XSI Mod Tool. This is
unrelated to the normals error. Are you sure everything was exported properly?
In order to select and move the bad faces, I made the following changes in SVN:
- Made normals_cache print the index of bad faces
- Added a FaceToPointSelections plugin, to convert face selections to points
- Fixed a bug with mesh_simple_deformation_modifier that prevented
selection from working correctly
You should now be able to use the following procedure to identify or
fix bad faces:
- Look in the debug output for the bad face numbers
- Select a bad face using SelectFaceByNumber
- Convert this selection to points using FaceToPointSelections
- Apply a modifier, i.e. TranslatePoints or JoinPoints (needs to be
restored to the new mesh format)
- Click the "Clear" button on this modifiers mesh_selection property,
so only the points belonging to the bad face get affected
The real solution for this would be a plugin that helps cleaning up
meshes and does things like removing faces smaller than a threshold.
Cheers,
--
Bart
------------------------------------------------------------------------------
_______________________________________________
K3d-development mailing list
K3d-development@...
https://lists.sourceforge.net/lists/listinfo/k3d-development
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