[Sidefx-houdini-list] Grouping Outside Faces

Marc-Andre Carbonneau marc-andre.carbonneau at ubisoft.com
Thu Jan 3 13:22:08 EST 2008


Hi Edmond,

I am completely green to Houdini so I cannot help you but I am curious about why you want to make a selection of the inner faces. What are you going to do with it exactly? What are you trying to achieve?
Thank for easing my curiosity! ;)

Marc-Andre

-----Original Message-----
From: sidefx-houdini-list-bounces at sidefx.com [mailto:sidefx-houdini-list-bounces at sidefx.com] On Behalf Of Edmond Earl Smith
Sent: January 3, 2008 1:13 PM
To: sidefx-houdini-list at sidefx.com
Subject: Re: [Sidefx-houdini-list] Grouping Outside Faces


Hey thanks for the help.  I got something to work that's a little like 
your suggestions.  I just had to do some fancy grouping.  One of the 
bigger challenges is going to be getting this information to transfer 
through DOPS and back into SOPS.  DOPS reassigns the RBD glued objects 
so that each group is a separate RBD object.  When it does this it 
reassigns the faces per object, so it's not like I can even create a 
group and try and reference the faces later once they've been 
simulated.  I have no clue how to grab these inner faces once the DOP 
sim has gone through.  Any suggestions? 

Thanks again so much,
Eddie

François Duchesneau wrote:


>Ok, here's how to do it. Forget the first method because I thought the 
>PolyExtrude would promote the points inside a group to the 
corresponding 
>extruded points. Anyway it's better the following way.
>
>For this, I assume your inner faces are all in pair of two because you 
>want to have many cubes from the extruded grid.
>
>1-Create an other PolyExtude Sop but check "Remove Shared Sides" on 
this 
>one.
>2-Append an AttribCreate after the second PolyExtrude and create a 
>primitive attribute, let's say "inner" and set the value to 1.
>3-Append an AttribTransfer after the first PolyExtrude and set the 
>"Distance Threshold" to 0.001 for example.
>4-Create a Group Sop with "Group by Expression" set to $INNER==0
>
>... and you're done. You can also look at an example file I've posted 
on 
>the Exchange called "Transparent Shattered Glass" that uses an other 
>mechanism that put every coincident faces into a group without having 
to 
>duplicate the PolyExtrude.
>
>François
>
>François Duchesneau wrote:
>> I'm sorry. I answered too quickly without cross-checking what I was 
saiying.
>>
>> I think you'll have to do an intersection boolean operation with the 
>> "extrudeSide" group from the PolyExtrude.
>>
>> I test that and let you know.
>>
>> François
>>
>> François Duchesneau wrote:
>>   
>>> You can append a Group Sop before the extrude, set the type to "Point" 
>>> and go in the "edge" tab and check "Unshared Edges". This creates a 
>>> group of all points being the boundary. Invert the group with a 
boolean 
>>> operation inside that Group Sop to get all points that are not a 
boundary.
>>>
>>> All the edges in that group will be included inside the geometry after 
>>> the extrude.
>>>
>>> François
>>>
>>>
>>> Edmond Earl Smith wrote:
>>>   
>>>     
>>>> Hello everyone, I have a fractured object that I create by extruding a 
>>>> grid and partitioning the pieces.  I would like to group just the 
faces 
>>>> that are "inside" the object.  Much like the group extrudeSide when 
you 
>>>> use the polyextrude but without the outer faces, just the inner ones.
>>>>
>>>> thanks,
>>>> Eddie
>>>> _______________________________________________
>>>> Sidefx-houdini-list mailing list
>>>> Sidefx-houdini-list at sidefx.com
>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>>
>>>>   
>>>>     
>>>>       
>>> _______________________________________________
>>> Sidefx-houdini-list mailing list
>>> Sidefx-houdini-list at sidefx.com
>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>
>>>   
>>>     
>> _______________________________________________
>> Sidefx-houdini-list mailing list
>> Sidefx-houdini-list at sidefx.com
>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>
>>   
>_______________________________________________
>Sidefx-houdini-list mailing list
>Sidefx-houdini-list at sidefx.com
>https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>
_______________________________________________
Sidefx-houdini-list mailing list
Sidefx-houdini-list at sidefx.com
https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list



More information about the Sidefx-houdini-list mailing list