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Div

"plotting" Dop

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Hi,

I have a DOP simulation who works pretty well, and i want to "plot" animation to my objects, in order to modify manually some objects' animation... I try with the Dynamic CHOP and I get animations curves for my Fractured RBD, but I don't find the way to "plug" them on my geometry...

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Hey Div

if u just need to keyframe ur RBD's, then try out the RBD Keyframe Active DOP, "The RBD Keyframe Active DOP provides an easy way to have an RBD object transition from keyframed animation to simulated animation and back again."

hope this helps

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Thanks i will try this method... But I would like to get a new scene, with no DOP, just keyframed animation; is it possible ? Because i haven't an enough powerful computer to simulate and simulate again; And When i write the sim cache data to the disk(using File Data), it just take hours ... So a No-DOP scene will be perfect...

Edited by Div

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Just to clarify, you have a DOP Simulation you're happy with (including curves you exported using Dynamics CHOP), and now you want to apply that animation to other geometry? (i.e. you simulated with a low-poly model, and now you want to render with a hi-poly model?)

If so... I'm no CHOPs expert (so maybe someone else can think of a better way to get the data back into OBJ/SOP land) but you could use the chop function to extract the transformations from your DOP Sim and apply them to your objects. At the OBJ level (or on a Transform SOP), you would type for the tx something like:

chop("/obj/chopnet1/dynamics1/rbdobject1:tx")

And then do the same for the remaining translation channels, the rotation channels, and the pivot channels. (Or to be more Houdini like, you could simply use: chop("/obj/chopnet1/dynamics1/rbdobject1:$CH") for all the parameters).

Hope that helps.

Edited by B.Walters

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Yep, it's aproximatly this, I want apply that animation to the same geometry, in order to delete my DOP simulation...

I will try your tips

Thanks...

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Yep, it's aproximatly this, I want apply that animation to the same geometry, in order to delete my DOP simulation...

I will try your tips

Thanks...

Well if its the same geometry, and the DOP sim is already cached - then the easiest way to get the geometry out of DOPs is with an Object Merge SOP.

The path to extract the geometry has a bit weird syntax... it goes like this:

/Path/to/dopnet1:nameOfObject/dataYouWant

The data you want will almost always be "Geometry"

E.g.:

/obj/geo1/dopnet1:rbdobject1/Geometry

Wildcards also work, so you could do something like:

/obj/geo1/dopnet1:*/Geometry

/obj/geo1/dopnet1:Sphere_*/Geometry

The first example would extract all the geometry from your dopnetwork, and the second would extract any object that started with then name "Sphere_"

Edited by B.Walters

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I already have an object merge and it works, but the DOP sim is not cached : it's take much more time to compute than just play (and compute it), and Houdini crashes always before it finish.... I am on a really slow computer so I want to know if i can export the Dop sim's animation by the Dynamics CHOP ( already compute and saved under all formats) and apply it to my object, on a new scene, in order to only have keyframes on it and no sim...

And i try using using your chop function method and i couldn't succeed..

Thanks a lot

Edited by Div

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plunk down a File DOP - and read the help

this will let you write out your sim to a format called mySim$SF4.sim etc

then you can just read this data back in...

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Yep, i already did it, but Houdini crashes each times i try to write it ... So i'd like to find another solution

But i'll check the help, i found this node reading Houdini on the spot, may be the help can learn me more on it...

Edited by Div

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if Houdini is crashing when it tries to simulate your scene then there isn't anything that will help you...how can chops or whatever get/grab/export the transformational infomation if Houdini isn't able to calculate the simulation that creates that information?

I've never tried this but...

you could use the file DOP to write out the first 25 frames...

then read in those 25 frames to calculate the next 25

then read in those 50 frames for the next 25 etc etc...

not sure how well this would work but that's all I can think of...

HTH

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It simulates perfectly when it isn't writing on disk, with the file node, but crash after too many minutes when it try to write on the disk.... I have already calculate and exported a Dynamic CHOP file under all formats (chn, chan, bchn, etc...). How can I apply a such file on my object is a mystery for me...

I will try your method, writing sim piece by piece...

Thanks for helping me

Edited by Div

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I don't succeed, following your example scene... My object is RBD fractured object, from a geometry imported into houdini... It works differently with that type of object, or am i definitively stupid?

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Now we need someone whose better at chops than me, because this approach will work - but isn't too terribly clean/ideal:

dopsexample2.hip

You'll notice I've made extensive use of the opdigits() function. If you're not familiar with it, look it up! It's a great asset to any Houdini artist.

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That's should work, I am following your method, with my 200 objects........

Thanks!!!

Edited by Div

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Regarding simming to disk,

If you running out of memory,

on your dop Network, Untick Cache simulation and Allow Caching to Disk resolves some issues, especially if you just baking out the geometry.

hope this helps

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Thanks a lot for all of your support and help... I succeed to use the Dynamic CHOP correctly, and Aracid optimisation' tips help me to write my simulation to disk... Because of the deadline I finally choose an other option, i exported as an obj sequence my simulation to import it in xsi, to change the animation of some objects... It's not really optimised, but regarding the time i have to achieve this, and my beginner level in houdini, it was the most safe solution... Thanks again for your help...

Edited by Div

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