[Imstk-developers] Clearing surface mesh data on intialization

Thu Jul 27 18:42:27 EDT 2017

Could you point us out in the code to where initialize is called which
deletes your normals?

On Thu, Jul 27, 2017, 18:37 Milef, Nicholas Boris <milefn at rpi.edu> wrote:

> The issue is still there. I can put the UV seam code before all of the
> clears, but if the user for some reason calls this function and gives
> different vertices/triangles, then it won't work properly with the new
> data. This is because the normals and the UV seam vertices won't correspond
> to each other.
> ------------------------------
> *From:* Sreekanth Arikatla [sreekanth.arikatla at kitware.com]
> *Sent:* Thursday, July 27, 2017 6:26 PM
> *To:* Milef, Nicholas Boris
>
> *Cc:* Alexis Girault; imstk-developers at imstk.org
> *Subject:* Re: [Imstk-developers] Clearing surface mesh data on
> intialization
> Not a problem!
>
> On Thu, Jul 27, 2017 at 6:22 PM, Milef, Nicholas Boris <milefn at rpi.edu>
> wrote:
>
>> Yeah, sorry about that!
>> ------------------------------
>> *From:* Sreekanth Arikatla [sreekanth.arikatla at kitware.com]
>> *Sent:* Thursday, July 27, 2017 6:20 PM
>>
>> *To:* Milef, Nicholas Boris
>> *Cc:* Alexis Girault; imstk-developers at imstk.org
>> *Subject:* Re: [Imstk-developers] Clearing surface mesh data on
>> intialization
>>
>> I see, it must have reported Initialize methods from physics that are not
>> related to this.
>>
>> On Thu, Jul 27, 2017 at 6:14 PM, Milef, Nicholas Boris <milefn at rpi.edu>
>> wrote:
>>
>>> @Alexis But why should it be overwriting the normals? That's not derived
>>> data.
>>>
>>> @Sreekanth I wasn't reading carefully enough. I tried to find all
>>> references, but apparently Visual Studio finds everything with the same
>>> name as the method, not necessarily the surface mesh's method. Sorry about
>>> that.
>>>
>>> ------------------------------
>>> *From:* Sreekanth Arikatla [sreekanth.arikatla at kitware.com]
>>> *Sent:* Thursday, July 27, 2017 6:04 PM
>>> *To:* Milef, Nicholas Boris
>>> *Cc:* Alexis Girault; imstk-developers at imstk.org
>>>
>>> *Subject:* Re: [Imstk-developers] Clearing surface mesh data on
>>> intialization
>>>
>>> Initialize is called at the setup phase by readers as well as when the
>>> user creates the data. It is supposed to be only called only for
>>> initialization and reinitialization with new data. Can you point me where
>>> it is called in the physics?
>>>
>>> On Thu, Jul 27, 2017 at 5:57 PM, Milef, Nicholas Boris <milefn at rpi.edu>
>>> wrote:
>>>
>>>> Actually, to clarify, I don't think it's a big deal if it's used in the
>>>> physics classes, as long as it doesn't modify an already built mesh as I
>>>> describe in the previous message. I don't know what type of impact the
>>>> normals have in the physics classes.
>>>> ------------------------------
>>>> *From:* Imstk-developers [imstk-developers-bounces at imstk.org] on
>>>> behalf of Milef, Nicholas Boris [milefn at rpi.edu]
>>>> *Sent:* Thursday, July 27, 2017 5:53 PM
>>>> *To:* Alexis Girault
>>>>
>>>> *Cc:* imstk-developers at imstk.org
>>>> *Subject:* Re: [Imstk-developers] Clearing surface mesh data on
>>>> intialization
>>>>
>>>> If it were only called in the readers, I wouldn't have a problem with
>>>> it. But it's called in some of the physics classes too. It also clears data
>>>> such as normals that's been set (i.e., by the readers). I need some of that
>>>> data though to fix the UV seams.
>>>>
>>>> For meshes, Assimp is told to generate smooth normals and to join
>>>> identical normals. For most vertices, this works as intended, but for
>>>> vertices on UV seams, they can't be joined. Assimp smooths those vertices
>>>> by treating them as a single vertex, which I would want as the intended
>>>> behavior. So I need to go through all of the vertices and find the ones
>>>> with the same normals and positions, but the normals get cleared by the
>>>> initialize function. Assimp's behavior is correct (I can't think of another
>>>> way we would want it to deal with these problems).
>>>> ------------------------------
>>>> *From:* Alexis Girault [alexis.girault at kitware.com]
>>>> *Sent:* Thursday, July 27, 2017 5:26 PM
>>>> *To:* Milef, Nicholas Boris
>>>> *Cc:* Sreekanth Arikatla; imstk-developers at imstk.org
>>>> *Subject:* Re: [Imstk-developers] Clearing surface mesh data on
>>>> intialization
>>>>
>>>> Is `initialize` only used in the readers currently? I believe the goal
>>>> of that function was just to set vertices, triangles, or any other topology
>>>> information needed in a single function. It should only be used after the
>>>> constructor as a utility as far as I understand, so there shouldn't be data
>>>> already set in the mesh at that point.
>>>>
>>>> When/where is this function currently called and creating an issue in
>>>> your case?
>>>>
>>>> Also, I think the `clear `should only delete the derived data computed
>>>> by the initialization input. Is it doing more than that now which would
>>>> explain why it deletes your data?
>>>>
>>>> I think having an `initialize` function that clears derived data fields
>>>> and set core parameters is good, we need to make sure it is called at a
>>>> good place and does not remove some unexpected fields (but I just think it
>>>> should be called before you try to set any data in it)
>>>>
>>>> Alexis Girault
>>>> R&D Engineer in Medical Computing
>>>> Kitware, Inc.
>>>>
>>>> http://www.kitware.com
>>>> (919) 969-6990 x325
>>>>
>>>> On Thu, Jul 27, 2017 at 5:03 PM, Milef, Nicholas Boris <milefn at rpi.edu>
>>>> wrote:
>>>>
>>>>> For now, I can just put the seam computation before the clear.
>>>>> However, this will break if the vertex order changes or something like
>>>>> that. Basically, what I'm trying to say is that I would want users to know
>>>>> explicitly if they're messing up their data. A reinitialize function
>>>>> doesn't convey this imo.
>>>>> ------------------------------
>>>>> *From:* Imstk-developers [imstk-developers-bounces at imstk.org] on
>>>>> behalf of Milef, Nicholas Boris [milefn at rpi.edu]
>>>>> *Sent:* Thursday, July 27, 2017 4:47 PM
>>>>> *To:* Sreekanth Arikatla
>>>>>
>>>>> *Cc:* imstk-developers at imstk.org
>>>>> *Subject:* Re: [Imstk-developers] Clearing surface mesh data on
>>>>> intialization
>>>>>
>>>>> I guess where I'm stuck at is why we have an initialize function to
>>>>> begin with. I still can't think of a use-case where we can't either 1) make
>>>>> a new mesh or 2) modify the components of the old mesh.
>>>>> ------------------------------
>>>>> *From:* Sreekanth Arikatla [sreekanth.arikatla at kitware.com]
>>>>> *Sent:* Thursday, July 27, 2017 4:37 PM
>>>>> *To:* Milef, Nicholas Boris
>>>>> *Cc:* imstk-developers at imstk.org
>>>>> *Subject:* Re: [Imstk-developers] Clearing surface mesh data on
>>>>> intialization
>>>>>
>>>>> Hi Nick,
>>>>>             If you want to preserve the normals, you can add normals
>>>>> to the Initialize function arg. If the normals are supplied, initialize
>>>>> clears the previous data before assigning.
>>>>>
>>>>> On Thu, Jul 27, 2017 at 4:01 PM, Milef, Nicholas Boris <milefn at rpi.edu
>>>>> > wrote:
>>>>>
>>>>>> No, I don't. I need to preserve the original normals that ASSIMP
>>>>>> imports because ASSIMP calculates the normals correctly. Otherwise, I can't
>>>>>> identify the UV seams.
>>>>>>
>>>>>> I can just do this computation in the SurfaceMeshRenderDelegate, but
>>>>>> I'm not sure if the normals are used elsewhere after reinitializing the
>>>>>> meshes. But isn't reinitializing a mesh dangerous in a multithreaded
>>>>>> environment anyway?
>>>>>> ------------------------------
>>>>>> *From:* Sreekanth Arikatla [sreekanth.arikatla at kitware.com]
>>>>>> *Sent:* Thursday, July 27, 2017 3:55 PM
>>>>>>
>>>>>> *To:* Milef, Nicholas Boris
>>>>>> *Cc:* imstk-developers at imstk.org
>>>>>> *Subject:* Re: [Imstk-developers] Clearing surface mesh data on
>>>>>> intialization
>>>>>>
>>>>>> It could be used in some cases depending on the scenario. Do you plan
>>>>>> to call this at every frame?
>>>>>>
>>>>>>
>>>>>> On Thu, Jul 27, 2017 at 3:53 PM, Milef, Nicholas Boris <
>>>>>> milefn at rpi.edu> wrote:
>>>>>>
>>>>>>> Is that a useful use case though? Why not just make a new mesh?
>>>>>>> ------------------------------
>>>>>>> *From:* Sreekanth Arikatla [sreekanth.arikatla at kitware.com]
>>>>>>> *Sent:* Thursday, July 27, 2017 3:52 PM
>>>>>>> *To:* Milef, Nicholas Boris
>>>>>>> *Cc:* imstk-developers at imstk.org
>>>>>>> *Subject:* Re: [Imstk-developers] Clearing surface mesh data on
>>>>>>> intialization
>>>>>>>
>>>>>>> Hi Nick,
>>>>>>>             This is cleared in case one wants to reinitialize the
>>>>>>> mesh with a different data. Initialize should only be called at
>>>>>>> initilization or at runtime if the mesh data itself changes.
>>>>>>>
>>>>>>> On Thu, Jul 27, 2017 at 3:31 PM, Milef, Nicholas Boris <
>>>>>>> milefn at rpi.edu> wrote:
>>>>>>>
>>>>>>>> I'm modifying the SurfaceMesh class currently, but why is all the
>>>>>>>> data cleared on initialization? Is this necessary? I ask because I need
>>>>>>>> this data to correct for the normals seams.
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> Imstk-developers mailing list
>>>>>>>> Imstk-developers at imstk.org
>>>>>>>> http://public.kitware.com/mailman/listinfo/imstk-developers
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Sreekanth Arikatla, Ph.D.,
>>>>>>> Senior R&D Engineer,
>>>>>>> Kitware, Inc. <http://www.kitware.com>, Carrboro, NC.
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Sreekanth Arikatla, Ph.D.,
>>>>>> Senior R&D Engineer,
>>>>>> Kitware, Inc. <http://www.kitware.com>, Carrboro, NC.
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Sreekanth Arikatla, Ph.D.,
>>>>> Senior R&D Engineer,
>>>>> Kitware, Inc. <http://www.kitware.com>, Carrboro, NC.
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Imstk-developers mailing list
>>>>> Imstk-developers at imstk.org
>>>>> http://public.kitware.com/mailman/listinfo/imstk-developers
>>>>>
>>>>>
>>>>
>>>> _______________________________________________
>>>> Imstk-developers mailing list
>>>> Imstk-developers at imstk.org
>>>> http://public.kitware.com/mailman/listinfo/imstk-developers
>>>>
>>>>
>>>
>>>
>>> --
>>> Sreekanth Arikatla, Ph.D.,
>>> Senior R&D Engineer,
>>> Kitware, Inc. <http://www.kitware.com>, Carrboro, NC.
>>>
>>>
>>
>>
>> --
>> Sreekanth Arikatla, Ph.D.,
>> Senior R&D Engineer,
>> Kitware, Inc. <http://www.kitware.com>, Carrboro, NC.
>>
>>
>
>
> --
> Sreekanth Arikatla, Ph.D.,
> Senior R&D Engineer,
> Kitware, Inc. <http://www.kitware.com>, Carrboro, NC.
>
>
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