[Sidefx-houdini-list] local variables in VOP SOPs

Sean Lewkiw seanl at rainmaker.com
Tue Dec 18 15:30:31 EST 2007


Well, there will be times you won't have access to the VOP to add the 
parm importing, so you might have to use the point expression to access 
the value in question. 

Sean

Andrew D Lyons wrote:
> It's been a while since I've wanted to put an expression in a Vex OP,
> but from memory it was using an OP that hadn't exposed the
> import_attribute VOP attr name string as a parm. As a result I wanted
> to use opinput to pull in an attr from the input SOP and couldn't.
> Maybe better OP creation would have provided another workaround...
>
> Cheers
>
>
>
> On 18/12/2007, Ivan DeWolf <ivan at martian-labs.com> wrote:
>   
>> also, why would you want to? if you're asking Houdini to solve some complex
>> expression in an argument field of a custom VEX SOP, doesn't it make more sense
>> to do that computation in your VEX code? (or VOP net, whatever) you have access
>> to the same point attributes, and you're already creating code (or nets)...
>>
>> having said that, however, VEX (and VOPs) seems unable to read int point
>> attributes, and 2-dimensional float point attributes. ID is an int point
>> attrib, and life is a 2-d float point attrib.... so I usually precede my VEX
>> SOP with a point SOP and set $CR to $LIFE and $CG to $ID and access Cd in the
>> SOP, or something similar.... a minor hassle, but worth noting... (unless this
>> has changed in H9.?.???)
>>
>>
>> Quoting Peter Bowmar <pbowmar at gmail.com>:
>>
>>     
>>> No Houdini locals work in VEX/VOP nodes. You have to put it into the
>>> VOPnet itself as a Parameter VOP to get it to import. This is how VEX
>>> works. It's for speed, as local variables are relatively slow to
>>> calculate whereas the pure VEX is very fast.
>>>
>>> Cheers,
>>>
>>> Peter B
>>>
>>> On 18/12/2007, Andrew D Lyons <tstexture at gmail.com> wrote:
>>>       
>>>> Yeh - I hear you. Some Houdini locals work, and some don't from
>>>> memory. I'm surprised $LIFE doesn't.
>>>>
>>>> Good $localVar and expression support in Vex OP UI parameters would be
>>>> the icing on the vex OP cake IMHO. Often it's necessary to wrap vex
>>>> OPs in a HDA subnet that handles all the attribCreate nonsense for
>>>> artists, but then you end up with 2 ops for every purpose in your
>>>> menus. One that does the raw vex number crunching and one that has
>>>> high level bells and whistles for users. Often they are named in a
>>>> similar way, and then people have to remember which OP is the decoy
>>>> and which is the money (depending on how they look at it.)
>>>>
>>>> This brings me to another long-standing RFE - the ability to load a
>>>> hda - and have it accessible - but yet not appear as clutter in your
>>>> OPmenus. I thought that was going to be part of H9 - but I'm yet to
>>>> see it. Anyone know what happened to that one?
>>>>
>>>> Cheers
>>>>
>>>>
>>>>
>>>> On 17/12/2007, Jerry Corda-Stanley <jerry at intelligentcreatures.com> wrote:
>>>>         
>>>>> Well I created the VOP SOP in H9, and wanted to stick $LIFE in the
>>>>>           
>>> parameter
>>>       
>>>>> field of the VOP I created to change the colour.
>>>>> I was trying to keep it neat with out messing about with attribute
>>>>>           
>>> creates
>>>       
>>>>> and so on.
>>>>>
>>>>>
>>>>> ----- "Andrew D Lyons" <tstexture at gmail.com> wrote:
>>>>>           
>>>>>> In the SOP parameters or in the VOPnet itself?
>>>>>>
>>>>>> Traditionally there have been problems with putting complex
>>>>>> expressions in the parms of a VEX OP. Often you have to override VEX
>>>>>> parms by creating an attribute of the same name and type with an
>>>>>> attribCreate SOP further up the chain. If you have a parameter VOP of
>>>>>> the same name you generally pass things in that way.
>>>>>>
>>>>>> Cheers
>>>>>>
>>>>>> On 17/12/2007, Jerry Corda-Stanley <jerry at intelligentcreatures.com>
>>>>>> wrote:
>>>>>>             
>>>>>>> How do I get local varaibles such as $ID and $LIFE to be recognised
>>>>>>>               
>>>>>> in a VOP SOP?
>>>>>>             
>>>>>>> I put together a SOP to futz around with stuff and it's complaining
>>>>>>>               
>>>>>> that the variables
>>>>>>             
>>>>>>> are undefined. So how do I define them?
>>>>>>> _______________________________________________
>>>>>>> Sidefx-houdini-list mailing list
>>>>>>> Sidefx-houdini-list at sidefx.com
>>>>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>>>>>
>>>>>>>               
>>>>>> --
>>>>>> =======================================
>>>>>> Andrew D Lyons | Digital Artist | http://www.tstex.com
>>>>>> =======================================
>>>>>> _______________________________________________
>>>>>> 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
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>>>>>
>>>>>           
>>>> --
>>>> =======================================
>>>> Andrew D Lyons | Digital Artist | http://www.tstex.com
>>>> =======================================
>>>> _______________________________________________
>>>> Sidefx-houdini-list mailing list
>>>> Sidefx-houdini-list at sidefx.com
>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>>
>>>>         
>>> _______________________________________________
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>>>
>>>       
>> -Ivan
>>
>> ---------------------------------------------------------
>> "Perfection is achieved when nothing else can be removed"
>> -Yvon Chouinard
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>>
>>     
>
>
>   

-- 
Sean Lewkiw
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