[Sidefx-houdini-list] VOPSOP by ID

Jordan Halsey jordanhalsey at gmail.com
Fri Nov 30 10:18:45 EST 2012


Wow funny, I use the timeblend sop with timewarp sop all the time and
thought that there must be a technical reason why you could not use that
node...


On Fri, Nov 30, 2012 at 7:15 AM, Nick Nimble <nick at nicknimble.com> wrote:

> Hi Nico!
>
> Gha, what a joke! It works flawlessly. Thank you very much my friend :-)
> Lucky Mark E. was fooled by the challenge as well, which in turn makes me
> feel less stupid ;-).
>
>
> Cheers,
> Nick, be Nimble
> +31 622 4243 94 | www.nicknimble.com | www.facebook.com/nicknimble
>
> On 11/30/12 4:09 PM, Nicolas Delbecq wrote:
>
>> Maybe I'm missing the point here but can't you just use the timeblend sop
>> ?
>> If an id attribute is present it will use that instead of the pointnumber
>> to interpolate the positions...
>>
>> On Fri, Nov 30, 2012 at 3:01 PM, Nick Nimble <nick at nicknimble.com> wrote:
>>
>>  Hi Mark,
>>>
>>> Tnx for your input.
>>>
>>> I like your thinking! How ever I have zero experience with writing vex
>>> code. I've tried using the inline vop, but I can't get it to work. I have
>>> two inputs in my inline vop: id (int)  and pointCloudFile (string) and an
>>> Output name: handleOut handle
>>>
>>> Code:
>>> string pcf = $pointCloudFile;
>>> int idIn = $id;
>>> int handle = pcopen(pcf, id, int idIn, float 2, int 1);
>>> $handleOut = handle;
>>>
>>> The problem is, is that I don't know if my unknowingness is the problem
>>> or
>>> that our little trick doesn't work in the first place.
>>>
>>>
>>> Cheers,
>>> Nick, be Nimble
>>> +31 622 4243 94 | www.nicknimble.com | www.facebook.com/nicknimble
>>>
>>> On 11/30/12 1:54 PM, Mark Elendt wrote:
>>>
>>>  Hi Nick,
>>>>
>>>> I don't know if this would work or not, but could you build a point
>>>> cloud based on id's?  You don't have to organize point clouds in
>>>> space, you can use any "space" you want (i.e. color or ID).  So, using
>>>> an id point cloud would let you look up the attributes based on id...
>>>>
>>>> If this works (and I don't know 100% if it will), feel free to post
>>>> the answer on the list.
>>>>
>>>> Cheers,
>>>>
>>>>
>>>> On Friday Nov 30 at 13:14, Nick Nimble wrote:
>>>>
>>>>  Yes,
>>>>>
>>>>> I want to retime or slow them down. I would like to beable to blend
>>>>> between
>>>>> 2 frames. Initially I would like to not only linearly blend between the
>>>>> points but also use to velocity to introduce some curvature. This will
>>>>> only
>>>>> be visible in very extreme situations, but I want it to visually work
>>>>> on
>>>>> a
>>>>> macro level.
>>>>>
>>>>> The goal is to retime 24FPS particels to say 1000FPS, like Discoveries
>>>>> Timewarp.
>>>>>
>>>>> Cheers,
>>>>> Nick, be Nimble
>>>>> +31 622 4243 94 | www.nicknimble.com | www.facebook.com/nicknimble
>>>>>
>>>>> On 11/30/12 12:57 PM, Alvin Yap wrote:
>>>>>
>>>>>  For each particle, you need to connect it to the next (future) frame?
>>>>>> If
>>>>>> you only need a linear blend, you could store the current velocity
>>>>>> value
>>>>>> and then you should know the next position in time at the current
>>>>>> frame
>>>>>> yes?
>>>>>>
>>>>>> Alvin
>>>>>>
>>>>>>
>>>>>> On Fri, Nov 30, 2012 at 11:50 AM, Nick Nimble <nick at nicknimble.com
>>>>>> <mailto:nick at nicknimble.com>> wrote:
>>>>>>
>>>>>>      Hi Alvin,
>>>>>>
>>>>>>      How would you do that? Besides I also want to be able to look
>>>>>>      ahead of time.
>>>>>>
>>>>>>      In its simplest form I want to use a timeshift node connected to
>>>>>>      the second and one to the third input of a VOPSOP and import an
>>>>>>      attribute by $ID instead of PT.
>>>>>>
>>>>>>      Cheers,
>>>>>>      Nick, be Nimble
>>>>>>      +31 622 4243 94  <tel:%2B31%20622%204243%2094>  |
>>>>>> www.nicknimble.com <
>>>>>> http://www.nicknimble.com>  |www.facebook.com/nicknimble  <
>>>>>> http://www.facebook.com/****nicknimble<http://www.facebook.com/**nicknimble>
>>>>>> <http://www.**facebook.com/nicknimble<http://www.facebook.com/nicknimble>
>>>>>> >
>>>>>>      On 11/30/12 12:44 PM, Alvin Yap wrote:
>>>>>>
>>>>>>       How about storing the previous frames' data as attributes on
>>>>>>> each
>>>>>>>      particle?
>>>>>>>
>>>>>>>      Alvin
>>>>>>>
>>>>>>>
>>>>>>>      On Fri, Nov 30, 2012 at 11:22 AM, Nick Nimble
>>>>>>>      <nick at nicknimble.com <mailto:nick at nicknimble.com>> wrote:
>>>>>>>
>>>>>>>          Hi!
>>>>>>>
>>>>>>>          I'm working on a method to re-time aka interpolate
>>>>>>> particles.
>>>>>>>          I would like to use a vopsop and do this as a post process.
>>>>>>>          The idea is to use the point position of the neighboring
>>>>>>>          frames and their velocities to calculate an in-between
>>>>>>> position.
>>>>>>>
>>>>>>>          The problem is, a vopsop works by point numbers and not
>>>>>>>          particles ID's and since point-numbers change when a
>>>>>>> particle
>>>>>>>          dies...
>>>>>>>
>>>>>>>          Any suggestions? I was thinking about the sort SOP, or
>>>>>>>          something like that. A method to match the point number by
>>>>>>>          the particle ID. Still this would result in missing
>>>>>>>          point-numbers and I'm not sure if Houdini would like that.
>>>>>>>
>>>>>>>          --         Cheers,
>>>>>>>          Nick, be Nimble
>>>>>>>          +31 622 4243 94 <tel:%2B31%20622%204243%2094> |
>>>>>>>          www.nicknimble.com <http://www.nicknimble.com> |
>>>>>>>          www.facebook.com/nicknimble <http://www.facebook.com/**
>>>>>>> nicknimble <http://www.facebook.com/**nicknimble<http://www.facebook.com/nicknimble>
>>>>>>> >>
>>>>>>>
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-- 
**
*Jordan Halsey**
*
maya | houdini | nuke | ae
*www.jordanhalsey.com*



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