VMT 009 - HOUDINI - How To Control Fracture Simulations

[@KevRyanCG]

Quite possibly the clearest tutorial out there explaining how animate and set the active points over a packed object. I definitely learned something new from this tutorial, thank you.

[@MIXTraining]

Thank a lot for saying that Kev, really happy you found it useful

[@근토-x2d]

lnj kt yo

[@Ferocious_Imbecile]

Always appreciate your excellent Houdini tutorials. Thanks a lot.

[@albertcallejoamat7837]

Good, SIMPLE tutos about Simple but USEFUL functions in Houdini ... thankyou

[@SowminiNathan0825]

I agree with Kev. After hours of trying, this tut solved my issue!! Thank you so much

[@benwil1785]

Hi there thanks very much for the tutorial. I'm a bit stuck at the part where you middle clicked on the toy and you had the attributes i@active in the list. I don't see any of these at all so the attribute wrangle code has no effect. Has something changed in the latest Houdini 19.0.531? what am I missing? Thanks for your help in advance!

[@TobiasSteiner]

The scaling up bounding sphere technique doesn't seem to generate uniform velocity to push out fracture objects. It seems to favor one vector over the other two. Try this in the anim_active_grp wrangle.... i@active = 1; i@speed = ch ("speed"); @v = set (@speed, @speed, @speed); If you setup a bounding sphere that scales up from the center point of a mesh, the results are not uniform as you might expect. Curious if I'm missing something or perhaps there's another method to achieve the desired effect.

[@MIXTraining]

you speed parameter needs to me a vector, 3 floats, then just do @v = @speed; that way you're passing 1 to the 3 channels which make a 1,1,1 vector basically averages the direction.

[@TobiasSteiner]

As you have this written it doesn't actually work when I try it. Seems this is not an easy problem to solve. Several have tried to solve this with various complicated methods since 2008 in Houdini that sort of work but aren't really the correct result. This is pretty simple in things like Maya where you simply use a field force to drive dynamics. There has to be an equally simple way to achieve this in Houdini right?

[@MIXTraining]

not really sure what you are trying to do, there is a force node to add force in a direction if you want you can use that

[@TobiasSteiner]

No, that's not it. That's a single path vector. Think "Volume Axis Force" in Maya. Force pushing out in all directions from a center point. The method you and I have been talking about still results in a single direction that is comprised of the combined vector value in x,y,z. A singular line of direction.

[@varomix]

you can use a magnet force for that, I added and example in the forum here, is a really common way to do destruction, nothing new and has been solved for years :) mixtrn.com/community/learnday-webinars/learnday-houdini-fracturing-basics/#post-17

[@lemmonsinmyeyes]

Hey @MIX Training I have a question; I’m following along with your tut but when I get to making a group in the sopsolver, I don’t have any of the options that you do. I can’t make a bounding box inside the group node. Is there something obvious I’m missing ?

[@MIXTraining]

click the checkbox under Keep in Bounding Regions

[@shanmugam2645]

this is clear that i have seen ever..grt

[@kaitlinrickard5162]

when i go into the sop solver, only one fragment shows in the view port instead of the all of them, any reason why?

[@emilmelikov8620]

Thanks Varomix for such a useful tutorial. I want to do the same thing by moving the object connected through the Attribute Transfer for more subtle effects, because Attribute Transfer has a nice Blend feature. I do the setup inside the SOP Solver, but can't achieve the decent result. I want to ask should I create the whole setup inside SOP Solver, or bring here a certain part? In may case, I only set up the Attribute Transfer part inside the SOP Solver, but there is something I do wrong that it works only for one frame.

[@MIXTraining]

yes by default those things work for just one frame in simulation, you have to set the sop geo to update every frame there is a parameter that says default behavior, change that to always, not my computer not sure if that’s the exact name

[@rajeshmohanty91]

reallly amazing .....after watching ur tuts i cant control my hand to click on subscribe button......easily understable, less time, amazing tricks ...cooollllll

[@robertromero7900]

I have a question. What was the vex code you added to force the glass out. I couldn't read it. Also. Is there a way you can animate the force to happen at a certain frame? Im new to Vex and need all the help I can get. Thanks for the tutorial by the way.

[@MIXTraining]

@v = set(0,0,10); you can change the frame on which you activate the pieces and the force will be applied at that frame

[@jMcWill781]

Great tutorial! Is there any way I can make that group boundary another object? So the geometry only becomes active when the other object comes close to it? there's probably a much easier way to do this but I am still Very new.

[@MIXTraining]

You can use any object to group points just change the option to custom shape and plug your object in the second input

[@jMcWill781]

Yes thank you I did eventually figure it out on my own. But maybe you could help me with another problem I'm having. I have an object set up as a particle source, but can't figure out how to add geometry to the particles (Like if I wanted to make each particle a piece of a shattered object or just a cube or something)

[@sealofthegods]

Hi Varomix how can I add dust coming from the debris for example at the end when we break a hole in the wall. I can't seem to separate the debris from my the original geometry. When I try to add debris and smoke it adds it to the whole geometry instead of just the debris. Can you help?

[@MIXTraining]

Put the debris on a group and emit only from that

[@sealofthegods]

@@MIXTraining Thank you for the quick response, unfortunately I'm a bit new to Houdini so I don't quite know how to go about getting that done continuing from your above tutorial.I tried using the attribute wrangle, the sopsolver node where you added the speed etc.. to push the particles outward in the autodop network I tried adding the debris shelf tool to that node What node would I use as the source to emit debris? And how do I put the debris in a group. Can you give me some pointers on how to get it done. Thank you so much.

[@MIXTraining]

Just group what is not static, if you use a box group you can just get everything that goes outside of it

[@sealofthegods4489]

MIX Training thank you so much with a lot of trial and error I used a group node, I copied all the parameters from the original group node(active_grp) to the new one I created. I put the new group node below the attribute wrangle then moved the timeline to frame 48 then selected the new group node and selected debris. And it worked. I added a volume to the points But now my new issue Is just trying to make the smoke follow the debris more fluidly. I tried sub-stepping by 12 but I don’t see much of a difference. Any pointers?

[@MIXTraining]

@@sealofthegods4489 can't tell just by that, join our discord community and post screenshots there so we can help you better

[@3dimensia]

Will glue constraints work with this multisolver? Because I added a glue plus a magnet force after this and it isn't breaking..

[@MIXTraining]

Yes it should work, if is not breaking then is working, is just too strong

[@Jaboli86]

Hi, thanks for the tutorial :-) Do you know if it's possible to do similar stuff when using not packed object? Say, for it's interaction with fluids?

[@MIXTraining]

First do this sim then the fluids interaction, not sure what you are doing, anything is possible

[@szolastudioanimacji8039]

@@MIXTraining Yeah, thanks, that's what I did in my test scene, and it worked (two DOP networks, in one I did some fracturing, and in the second fluid interaction). But what I was really trying to do, was to simulate creation of a waterfall, dynamically (so the geometry of the ground changes in time, then part of a rock rips off the hanging cliff and falls, and it all happens with flowing water). It kinda worked in the end, but I had to cheat some stuff due to massive collision issues between terrain and flowing water. If you're interested, I created a topic concerning that on SideFX forums. The link is: www.sidefx.com/forum/topic/66650/ I wonder if you may know a better (simpler? right?) way of doing this. Soon I'll be posting final result of that one in that topic.

[@MIXTraining]

@@szolastudioanimacji8039 there's no simple way in simulation, glad you got it to work

[@autentikum]

Thank you for saving me, really nice and clean tutorial!!!

[@hairetikaos]

I love these tuorials, I have a question I'm in houdini 17 and when I put the voronoi fracture node, the option "vizualice pieces" its doesn't show up, in fact is quite different, how to fix this?

[@MIXTraining]

click that tick mark to the right of the Name Prefix filed

[@hairetikaos]

Omg that was pretty hidden, I would never knew, thank you !!!

[@VlatkoDojchinoski]

Perfect tutorial! One question: how can I transfer the attribute `active`(attribute transfer) from one object to another inside the SOP? The object have to be imported as packed inside DOP, but the physics kick in that way. Also, I can't use attribute transfer for NON packed object inside SOP (I can't find way to do that). I have small sphere, and big sphere (Roberto in your case is big sphere). I want to transfer active from object to object, not with group node. Any hint? Tnx. Vlatko

[@MIXTraining]

Attribute transfer works for any kind of object, pack or non packed

[@danieldukome]

great tutorial! i don't know if others have the same problem, but when i render it on frame 1 with a glass shader i can see every single cut of the pieces. Do you know how to fix that?

[@MIXTraining]

Thank you, switch the geo man, is an old trick, use the non fractured geo for the frames that is complete, then switch it for the fracture part :)

[@ryangold6310]

Hey thanks for the tutorial! However, I can't seem to get this to work in Houdini 16. It only works if I do i@active = 0; (so the group makes parts on the sim in-active instead of activating them) and only if the group is static, not animated. Any advice?

[@MIXTraining]

I just did the same thing for Houdini 16.5 and it works exactly the same way, you might not be setting your object to static, you need to do that first, so you can make it active in the wrangle, also if you are animating the group, you need to change the Default Operation of the SOP Solver to Set Always

[@ryangold6310]

Oh that's it!! Thank you so much :)

[@MrKannanvfx]

Hi Mix, how can apply this to animated character(deforming static object)..any change we need to add in attribwrangle

[@MIXTraining]

That is not a easy task, you need to setup everything in a static frame then transfer the animation to that, not that simple to explain 😊

[@kishoreguntuku]

Hey Man, great tutorial. I have a doubt though, I tried a couple of bounding spheres to activate the points on various parts of the geo inside the sop solver using merge node. But it didnt help. Could you please tell me how i can fix that?

[@nassernajjar82]

Hi I tried to follow the tutorial on houdini 19 , unfortunately despite the tutorial was clear the destruction happened in the whole body not to the areas where I chose by point. Is it possible to contact you?

[@MIXTraining]

Use our discord channel

[@sauloarruda7881]

thank you! I was sawing another tutorial to do the same thing, but much more difficul than this! Thank you!

[@MIXTraining]

glad to help

[@birdaid5242]

question is voronoi fracture replaced or its two different things from object fracture

[@MIXTraining]

object fracture is just a shelf tool that creates a voronoi

[@GeorgeBigiakis]

Thank you for these tutorials, really useful! :) One question about this particular one. I tried using this technique over multiple fractured objects (Parts of a building), using the merge node to plug them all into the sop solver. Then I tried to group the points to be active using a custom bound volume using multiple spheres so that it would collapse at various places, yet nothing happens. Should I pay attention to anything in particular when doing this over multiple fractured objects?

[@MIXTraining]

Did you set the group option on the Attribute Wrangle? I always forget that :)

[@GeorgeBigiakis]

Yes, I had set that correctly, right now I tried exactly what you show, using 1 bounding sphere from within the group node and it work perfectly. prntscr.com/du3obx This is what I tried to do before, merging these prntscr.com/du3ogt in to use as bounding volumes but it didn't work at all? I guess I could use multiple group nodes instead of these spheres to achieve the same result. Thanks for the quick reply!

[@MIXTraining]

If those spheres are not going to animate at all, set the same parameter in SOPS, the simulation should pick it up, same setup as in the SOP solver but in SOP directly, and no need for the SOP SOlver

[@GeorgeBigiakis]

Thank you! This one worked perfectly! :D

[@Purbow]

Thank you !! Really need it!

[@EFANZPro]

awesome tutorial...question...can/how do i export the fracture simulation out to use in maya?

[@MIXTraining]

You can create a Houdini asset and load it in maya using Houdini engine like this >>> kzbin.info/www/bejne/farIk4KKqdCYa9k

[@peterhamlin1296]

easy and straight forward to the point! I really like this approach of tutorial. Thanks a lot :-)

[@geripogeripo]

Hi! It doesn't let me crate a group. It puts a Group Create instead. Help please. (Houdini 17.5.293)

[@MIXTraining]

That is the same thing

[@smylmvv]

Idk why it does not appear the "Ground plane" on the Houdini version 16.5.473? Live this one has!!

[@MIXTraining]

Ground plane has to be created inside a DOP network or from the shelf

[@Cybernetix3D]

Thanks for making all these tuts, you rock!

[@MIXTraining]

Thank you Tim I really enjoy doing this for you guys :)

[@sidinator100]

Hey thank you man! awesome tutorial! Got exactly what i wanted...

[@user-tm4uo9un2z]

most important question, how do i get those skins???

[@williamvalentin7647]

Thank you for the tutorial! But I cant for the life of me get the group to work in 17.5. I have the exact same setup, but the whole mesh keeps collapsing withouth respecting the bounding region sphere!

[@MIXTraining]

Not sure what it is, could be a million things, go to mixtrn.com and post on our community with pictures

[@williamvalentin7647]

@@MIXTraining Ok, thanks!

[@ParticleSkull]

Hey man, thx for your tutorials, it's awesome! What's your name, btw? Is it possible to use a intial speed (from initial state tab) for the newly activated fragments? Thx, Alvaro

[@MIXTraining]

Thank man, hehe my name is the same as yours Alvaro, everyone calls me Varo you can set the speed in that same wrangle where you activate them so they get their initial velocity, just like @v = (1,0,0);

[@ParticleSkull]

Are you serious? What a coincidence! That's cool :) Thx for the tip, bro

[@MIXTraining]

Totally serious hehe

[@kylestudios483]

Thanks mens for sharing us tutorial ...

[@MIXTraining]

You are welcome

[@chrisvfxstudio]

Thx a lot for your tutorial ! I'm learning houdini, and i don't have Mister Roberto.....can you help me to find it ? Thanks :)

[@MIXTraining]

Hi, glad you're enjoying the training, Roberto is just the Test Rubber Toy renamed :)

Great tutorial very informative.

[@MIXTraining]

Glad you like it

[@SahakSahakian]

Roberto4Prez hehe.... Awesome stuff. Thank you!

[@MIXTraining]

Thank you

[@aakashdhruve4021]

good one I am new to Houdini using Houdini 13 😅 I have problem with packed object in autodop and attrib wrangle can you explain how to do in houdini 13??

[@MIXTraining]

man, Houdini 13 is very different, why not use the latest version? something specific? VEX is very very very new in H13 and is missing a lot of stuff. I recommend using a newer version

[@aakashdhruve4021]

MIX Training bro actually I am working in a company,I asked for upgrade but they don't..

[@aakashdhruve4021]

MIX Training any other way to do..🤔

[@aakashdhruve4021]

MIX Training in 13😥

[@MIXTraining]

yeah that happens sometimes with studios. well packed prims and VEX were really new in H13 so you are going to have a hard time doing any VEX related stuff, maybe someone there can help you

[@polvy]

Hi! first o fall thank you so much for your tutorial, absolutely usefull. I have a couple of questions if you don't mind (sorry for bad english); 1- Why is important the input order of the sop solver? It wouldn't work if you change it? 2- Why is the rigidbodysolver taking the object even if it isn't conected to the first input? Thank you!! :)

[@MIXTraining]

because you want the simulation to first calculate the changes in the geometry and then evaluate that in other solver, the multi solver passes the object to all the solvers connected to it

[@z8editing]

really interesting video but i have an issue: i don't understand why, but i can't render packed geometry in redshift it does render the fractured geometry but not the the packed one for some reason keep up your tutorials they are really helpful for a beginner like me !

[@MIXTraining]

Z8' just use a convert node at the end and it will render, I think packed geo is on the works

[@z8editing]

thank you for the fast answer and yeah that would be interesting to see !

[@jafardashti1147]

Thanks for this. Really helpful technique.

[@MIXTraining]

Glad you like it, thanks

[@SahakSahakian]

Gotta love the SOPSolver

[@MIXTraining]

The SOP Solver is super useful

[@mirkozurlo4875]

Hi Vormomix! In Houdini 16 I don't see bounding sphere ...Why? :(

[@MIXTraining]

mirko zurlo my name is weird hehe, make sure you are un the handle tool, press enter or select it in the left

[@CTJonze]

you are amazing! thank you! I was just questioning this today, OMG!

[@MIXTraining]

I'm glad I did it, go make something really nice :) Thank you

[@zlanyi85]

Dear Varo! It's awesome... i just wondering how can i get back my textures after this sim... i started to migrate from the using of 3ds max to this fantastic software, but i have to learn a lot :) btw this. Once again: THANKS

[@MIXTraining]

Zoltán Lányi use an unpack node after the sim, thank you

[@zlanyi85]

Yeah!!!!! Thanks ! A lot of people are really happy about your easily understandable education work in here. Big hug from Hungary! Keep it up Bro!

[@MIXTraining]

Thanks man, glad to be of any help

[@tariq0513]

@@MIXTraining can't believe this is all i needed to do. Had been trying to figure this out for past 4 days.. Thank you sooooo much..

[@MIXTraining]

Great man, glad it works for you

[@ady7d77]

amigo , me puede ayudar a poner redshift a houdini 18 pls, ya trate mil veces y no pude y puse el script en .env, y nada, me puede ayudar?

[@MIXTraining]

Lanmas recientemente version ya trae soporte para h18

[@natanivan]

so helpful, thank you!

[@MIXTraining]

Yes this is great to know, you can basically do everything inside the SOP Solver, glad you found it usefull

[@DiogoSantosvfx]

hey Mix! Any idea why I can't do this on alembic obj? Dam I'm going mad here xD

[@MIXTraining]

convert to polygons first

[@DiogoSantosvfx]

I did it and it works :D now I'm trying to shatter some glass and I have the small fragments dancing in the ground lol still trying to figure out how can i stop them xD

[@MIXTraining]

drag force

[@DiogoSantosvfx]

should it go before or after the gravity? it still jitters lol :P i'm also trying with a pop drag and pop wrangler to set the v@v = 0; when v < 0.5; but nah it just doesnt stop xD

[@mrmaxim77726]

amazing! you did very good job!

[@MIXTraining]

thank you

[@bobcharlotte8724]

Dude I want that houdini UI skin!!

[@MIXTraining]

Is on our site, www.mix-training.com

[@user-tg2xn7yv9h]

謝謝

[@MIXTraining]

很高兴你喜欢它，谢谢