How to mark RBD objects as inactive?

[magneto]

Hi,

Not sure if inactive is the right word but basically when I have a simple pre-fractured building, playing the animation, the building immediately collapses by itself. Is there a way to mark it so they aren't active until another RBD object impacts them?

Otherwise even when I didn't pre-fracture it, the pieces start jittering slightly when playing the animation.

Thanks

[Hudson]

Hello Ryan!

This thread wil help you. Otherwise the digital tutors tutorial on destruction will:

http://forums.odforce.net/index.php?/topic/17660-fractured-pieces-of-a-deforming-object-acts-strange-after-collision/page__hl__+rbd%20+glue%20+network#entry107041

http://www.digitaltutors.com/11/training.php?vid=26120&autoplay=1

Edited July 31, 2013 by Hudson

[magneto]

Thanks Hudson. I checked out the thread, but isn't that about deforming geometry? I will check out the tutorial you mentioned but if someone knows which option to turn on/off, I would appreciate it

[Hudson]

If you have a digital tutors acount then just watch it and you will achieve exact what you are looking for.

Otherwise what you could do if u are using a glue network is simply to set the strength of the glue net to -1 inside the glue net SOP. Remember to refer to the last node inside youe glue_net SOP into your Glue_net DOP

Create a point cloud inside your Glue_net SOP and apply a strength attribute based on Cd or something then use a VOPSOP or attr-transfer(slower) to transfer the strength attribute to your glue_net. Remember that -1 in stength is completely static and everything above 0 is a strength-value. Also remember to include your ground object to the same glue-network. Doing so you wont need to activate/deactivate pieces instead just set the strength in your complete network.

Here is a different set-up of activating pieces if you don't have a ground:

http://forums.odforce.net/index.php?/topic/17652-voronoi-dynamics-question/page__hl__%2Bglue+%2Bnetwork

If it doesn't help then check this tut from sideFX:

http://www.sidefx.com/index.php?option=com_content&task=view&id=2350&Itemid=166

Good luck!

[substep]

if it's simple enough, sometimes I just make a DOP group (shelf tool) of the objects I want inactive, append an "active RBD.." dop, set to always, and "0". It's not very procedural, but sometimes you don't need it to be.

[magneto]

Thanks guys. I used glue constraints and not sure if this is related but I just manually enabled fracturing in the Voronoi Fracture Configure Object DOP using an expression where the impact occurs.

Not sure if this can be done procedurally at the time of impact but this worked for now.

Also since I am using dynamic fracturing (for practice sake), if the fracturing is enabled the building already collapses by itself, which is what I wanted to stop basically

[Skybar]

If you exclude your ground plane from the Impact Group (on the voronoi fracture config object dop), it won't break from that, which is probably what is happening. So something like * ^groundplane1 will make it break from anything except the ground.

[magneto]

Thanks that didn't work but when I just used "sphere" as your described, then it did. Although now the building doesn't shatter by itself, but now it doesn't fracture even when the ball smashes it on top. Probably I am missing something trivial.

I was just doing this for practice.

[Hudson]

Do you have a hip? It is muh easier to see where the problem is. Because it could be that you don't refer to the correct SOP-node inside the glue_pieceXX_to_piecexx geo node or it could be by the "override with SOP" parameter(set it to 1) in your glued_piece DOPs- node or it could be because you don't dissolve the network correctly. The answer is yes it can be done procedurally

Edited July 31, 2013 by Hudson

[magneto]

Thanks I attached it. Btw excuse the mess because I am trying different methods and didn't clean the unused nodes

house collapse dynamic fracturing.hip

[Solitude]

You should take a look at the "glue adjacent pieces" shelf tool, and the bullet masterclass video by sesi.

[Hudson]

The main problem could actually be that your sphere is falling in the middle of everything and in a perfect world with that kind of uniform building nothing would happen. the sphere would fall on the bricks and they would sustain since they don't break in uneven pieces. So I added some mtion to the ball and ground as well.

Here is your scene Ryan and also the test I did just to show how you could dissolve your glue net. But you could dissolve it in a thousends way depending on your taste

@Ian I did also tell him that, it is a superB lesson

dissolve_glue_net_ryan.hipnc

dissolve_glue_net.hipnc

Edited August 1, 2013 by Hudson

[magneto]

Thanks alot guys, I will add them to my next-to-watch lists. I was watching another beginner tutorial but he didn't mention any of these things

@Hudson: Thanks, I will check out the files right now, appreciate the time you spent on them

Btw is it better to use a specific solver like Bullet Solver DOP or should I always use the generic RBD Solver which seems to contain multiple solvers. I just don't know if this slows things down or not but the shelf button adds the generic one.

Not sure if this is shown in the bullet masterclass.

[Solitude]

I don't think it'd make a big speed difference. I haven't tested, but the stuff that isn't used isn't calculated, so the overhead "should" be minimal by having those sitting there inactive. Some people prefer doing it manually, I don't mind just using Rigid Body Solver and setting it to bullet. I like being able to switch to rbd easily sometimes, or adding dynamic fracturing, and it's got everything built in. *shrug* It's up to your personal preference I think... though I'd be curious to see if there are any speed differences by having the extra nodes in the scene.

[magneto]

Thanks Solitude, because I saw someone basically rip the RBD solver to shreds so it has only what he needs, but then I thought the switching must be pretty efficient already in Houdini. Just wanted to see what other gurus like you would think. I will also go with the generic ones I guess, as I think they are built for a reason.

[pbarua]

Hi,

Not sure if inactive is the right word but basically when I have a simple pre-fractured building, playing the animation, the building immediately collapses by itself. Is there a way to mark it so they aren't active until another RBD object impacts them?

Otherwise even when I didn't pre-fracture it, the pieces start jittering slightly when playing the animation.

Check this thread out:

http://www.sidefx.co...8820&highlight=

I used Modify Data DOP to create "colided" data that is boolean and it's value is 1. For it's Activation Parameter, I used dopnumrecords expression function so that colided data will be created on Impacts only. Then I grouped pieces using dopoption if there was colided data. I also used Active Value DOP and dopfield expression in it's Activation parameter to activate it only on Impacts. Finally group was used in dop forces mask.

ball_crashing_wall_effect_515.hipnc

Edited August 1, 2013 by Pradeep Barua

[Solitude]

Thanks Solitude, because I saw someone basically rip the RBD solver to shreds so it has only what he needs, but then I thought the switching must be pretty efficient already in Houdini. Just wanted to see what other gurus like you would think. I will also go with the generic ones I guess, as I think they are built for a reason.

^ If there is something not needed, I see the appeal behind keeping it clean, but the rigid body solver node specifically is pretty simple inside. I could see gutting things out of pyro or flip more so than this case, since there are a lot more nodes inside of those otls. Even then though, I find it's nice to have most of the additional options they've added to those nodes already there at my fingertips.