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sliver

Dynamic duplication effect

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Hello guys :)

I would like to know your opinions about how to achieve this duplication effect in Houdini :

For the moment, I emit particles which become directly RBD with RBD Point Object (I don't know if it's the most efficient and interesting method for this effect)

(I use Houdini since 6 month only)

7OidC.jpg

I'm stuck at the second step, when I want to emit 4/5 particles from each RBD wich is on the ground plane since 1 second. I'm a little bit lost in the Dop network with many duplications inside others duplications.

Thank you very much for your help.

split_RnD_003.hip

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It might be a little too different of a workflow, but it might work for your purposes. Check out my object hose tutorial for something like that:

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Great idea thank you kleer ! very interesting approach.

Do you know how is it possible to create in my example 4 boxes which are exploding at the same time at the frame 1 ? I have used a Copy sop without sucess.

Object_hose_001.hip

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This sounded like a fun problem and a perfect one to solve with Milan Suk's BulletSOP. Sorry if this doesn't directly answer your question about a DOPs based workflow, but I couldn't help myself :)

You'll need the latest BulletSOP (v2.0.9) for the example file to work. You can grab it here: http://forums.odforc...-bulletsop-209/

btSop_dynamic_split_v01.hipnc

Edited by cubiccube
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Hi cubiccube :)

Thanks a lot for your answer. It seems DOPs is not used by a lot of people so I have worked with BulletSop like you

this is my latest RnD from today : (file attached)

Your file is very complete !! but I don't see correctly the simulation, the PROPERTIES node has an issue for me : Invalid source sim:pointwrangle_INITIAL_VELOCITY_AND_BIRTH_ATTRIB

split_RnD_BulletSOP_006.hipnc

Edited by sliver

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What Houdini build are you using? And what BulletSOP version?

BulletSOP should be v2.0.9 and Houdini 12.5.469 is recommended (though I'm on 12.5.536 without problems).

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I'm on Houdini 12.5.371 with BulletSOP 2.0.9

Do you think that my houdini build could be the issue ? I'm going to setup H 12.5.469 monday

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Hello cubiccube, your file works like a charm on H 12.5.469. I'm analysing you setup to understand how you do it.

About the trembling motion, do you have an idea about how is it possible to create it ? In your opinion, is it done by an expression or a pocedural animation ?

Thank you

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About the trembling motion, do you have an idea about how is it possible to create it ? In your opinion, is it done by an expression or a pocedural animation ?

You can get that kind of jitter using basic sine functions. You could also use some noise. Or both: use sine functions to get your oscillations and use noise to vary the frequency and amplitude. You could do these with expressions if you wanted but imo a vopsop or wrangle node is more quick and clean.

The other component to the jitter in your reference is that it builds as the boxes get closer to splitting. In my example file I was assigning a randomized counter to each box once its velocity dropped below a certain threshold. You could use that same counter (or another based on different logic) to drive the ramping up of the jitter.

Now, implementing it with BulletSOP might be a little tricky since you can only animate static (mass = 0) objects. I believe there's an example in the hip file Milan includes with each release that shows how to get around this by stashing your objects mass and swapping it out when you want it to become active.

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thank you papicrunsh

Cubiccube your ideas about the jitter are very useful for me. I have check every example in the hip file to understand better how to have a nice control. Do you remember what example is the most interesting for this effect ?

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Hello cubiccube and everybody :)

I'm back on this wip (currently working with H13 and BulletSop 2.0.10)

This is my lastest update :

And I would like to improve my simulation, by addind two things :

1 - A time offset in each secondary duplication (because in my file the four objects appear at the same time) and it's very linear.

Like at : 00:03 in this great reference :

And

2 - To know how to emit 4 objects with the foreach1 instead of the scatter, because I haven't a lot of control. And with a popnet my attributes like bt_index are lors.

Do you have an idea ? I'm learning Houdini, and I don't know vex expression for the moment so my file is less optimize that yours cubiccube.

Thank you very much for your help.

split_RnD_BulletSOP_007.hip

Edited by sliver

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There are a lot of ways you could go about offsetting the timing (duplicating your foreach sops and staggering the timing of their switches or something along those lines), but I'm not sure this is the best way to solve the "linear" look you're talking about. You'll get a more seamless effect if, instead of scattering points on top of the actual geometry, use the property point position (with a very small random offset, +/-.1) as the origin for your new piece points (you can use a line or add sop to make the initial points or, in H13, use Attrib Wrangle).That way everything originates from the same spot and explodes outward instead of appearing in midair. Not exactly the answer you're looking for but give it a shot and see if it helps.

Also, you scene will simulate much more quickly if you bring the polygon count on your geometry way down. Pipe the initial geometry into a shrink sop to generate a convex hull (what Bullet converts your geometry into anyway) and play with the sliders until you get something closer to 100 polys.

Good luck!

Edited by cubiccube

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Oh sorry for the late reply, I have forget.

 

Thank you for your advices. I'm going to work on it !

 

PS ! The "linear" pop up is cause by the condition of duplication. Every 20 frames. And I would like to add a little bit of  variation to duplicate them in the time. Like in the Harry potter reference. Not  4  objects in 1 frame, but 4 objects created in 20 frames. To avoid a massiv pop up.  I don't know if it's more clear :-)

 

Have a good day

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