Tearing & Deforming Metal using RBD Tools in Houdini Part 2

[@ДмитроСказон]

You are real Master of Digital Univerce!! Bravo!!

[@bubblepins]

Thanks!

[@alberttaruno]

Excellent tutorial series, thank you! It helped me a ton for learning houdini's RBD system.

[@bubblepins]

Thanks for watching! I'm happy to help!

[@saebr]

Thanks a lot for your efforts. Learning a lot. Could you please do a tutorial on the spinning box you show in this tutorial. Also if you could show us how to add smoke on a simple wall distruction Sim, not via the shelf tool... Mainly how to set it up ourselves in H18. Those will be 2 great tutorials. Again, thanks for sharing your knowledge.

[@bubblepins]

The cube chipping! Sure, that's very simple. I'll try to do something quick maybe next week. I got a few more videos I just finished editing that I got to release in the next few days and I'll squeeze the cube chipping in between my schedule. Thanks for watching!

[@saebr]

@@bubblepins Thanks a lot.. Your tutorials are really helpful. On the cube chipping, even though it might be very basic, but could you please show the entire process.. And how you added the velocity and angular velocity. Also please do a simple somke from rbd destruction that you explain to us in your beautiful way, so that we don't rely on the shelf tool. I might be asking too much... But it's highly appreciated... You are amazing. Thanks again.

[@sohamshah1753]

I found that using a remesh after rbd deform pieces will actually give it more natural metal bending look, try it if you likd ✌️

[@bubblepins]

Thanks for the tip! I'll give it a try.

[@nilestanycosta863]

Great job, loving these last ones!

[@metaturnal]

Hi, can you tell me how I can deform metal without breaking it? And how to make adjust how strongly it is deforming? I use an object that has a protruding part that should just crumple up, but instead it just pushes the part underneith away unrealistically..

[@bubblepins]

I think you might be looking for something like the new H19 Vellum Unified Solver deform destruction, which I haven't had a chance to do a video on yet. But I had a previous video on a very similar effect that I called "SDF Destruction" and it deforms an object upon impact without fracturing it: kzbin.info/www/bejne/l2nbeZuge8qNhJI Hope that helps!

[@hanheecho6437]

How do I stop the shaking those pieces after the ball through the wall?

[@bubblepins]

This is a very common issue, there are a few factors that may cause the shaking, too much external forces acting on the pieces like bounce. BUT I do find that in this particular example where you have pieces fracturing another one while keeping selective constraints still connected it is helpful to increase the elasticity and harden it as quickly as possible to try to keep it in position after the ball collides. Try that and it's also helpful in the RBD Solver node to increase friction, lower bounce, & increase substep. See if that works out.

[@hanheecho6437]

@@bubblepins Thanks, will try!

[@Cheesyeggbake]

how would you use the rbd configure SOP in junction with the rbd connected faces SOP? I'm having trouble passing the rbdconnected prim attributes through the configure node.

[@bubblepins]

oh I know what you mean, its because the RBD Configure node packs the rbd objects which causes a conflict with the RBD Connected Faces node. If you change the order of the nodes a bit, try putting the RBD Configure node at the end right before the solver. Then after the dopimport node, put down a unpack node then you can use the RBD Disconnected faces. Hope that helps!

[@Cheesyeggbake]

@@bubblepins Right so place connected faces node before the configure node, then after the the deformpieces node the deleting dis-connected face node no longer works BUT the four prim groups created by the original connected faces node are still stored in the geo. Something is happening that keeping the disconnected faces node from working and I think its how the configure node packs them. Anyway with some clever grouping and deleting I can recreate the same effect I'd get from the disconnected faces node. It isn't pretty but hey, it works. Hope that makes sense. Thx for the tutorial btw!

[@bubblepins]

@@Cheesyeggbake Thanks! Drop down an Unpack node before the Disconnected Faces node. Because the geometry is still packed after the DopImport node. Hope that makes sense, it's a mouthful.

[@FullMetalHeart_one]

awesome tutorial and explanation, thank you so much! Just want to ask: what if I want to export that as a VTA texture? From what I experienced, the VTA output node needs a dopnet to work (it will calculate also with a geometry Null but then the result wont work in UE or whatever engine) but we dont have any in this scene. If I set the object as Static, that will create the dopnet but the simulation brokes

[@bubblepins]

Do you mean VAT (Vertex Animation Textures)? I did a simple test for vertex animation a very long time ago using mantra to render it out and imported it to UE4 and it worked! However I could never get collisions working with it so I gave it up. The best thing about it is that you can export fluid sims into UE4 and at the time Niagara wasn't out yet, so this was a breakthrough for me. But VAT isn't very necessary anymore, since Houdini and UE have a lot of tools to make the two applications more seamless. You can just export the fluid particles from Houdini and import it into UE through niagara system. Now I haven't tried this yet. But theoretically it should work. Hope this all helps!

[@FullMetalHeart_one]

@@bubblepins yes, I meant VAT, just mispelled two times haha. Ty for the answer btw, I'll try the Niagara workflow as well :)

[@defonten]

Hi, thanks for the great tutorial! Liked and subscribed instantly! it all works perfectly I have just one question. Can you please also tell me why am I getting this slight but constant jittery movement on all chunks after the ball pierces the surface and how to fix it? Thanks a lot in advance!

[@bubblepins]

The jittery movement may be due to several possible reasons. The first thing, I can think of is the RBD Deform Pieces node, sometimes it struggles to figure out which pieces are adjacent to weld together, so you can help it by filling in the piece parameter on the RBD Deform Pieces node. This would be the attribute Name Attribute for the blast pieces, which should be by default "name". And remember to select "Constraint" for Boundary Connection. Is your collision geometry a little more complex with sharp pointy corners or some sort? If so, I would suggest to turn up the substeps in the RBD solver → Advanced (tab) → DOP Network (expand) → Substeps. And double check if you have the RBD Constraints on the edges of the blast pieces similar to 11:04 in this video. Also try reducing the bounce in the RBD solver → Solver (tab) → Bullet Object (sub tab) → Bounce. Another thing I can think of it is to increase the plasticity 17:00 in the video, because this will harden the blast pieces almost immediately if the parameter is high enough, causing the pieces to stay in place. Hope this helps!

[@defonten]

@@bubblepins Thanks I appreciate your prompt reply! Unfortunately none of this helped and all chunks still jitter. I downloaded your file and they jitter even there. If you would be able to fix it in your scene and reupload it whenever you'd have some time - that would be really awesome! But no worries, I will also try to fiddle with a few parameters to see if it helps fight the jitter. Thanks a lot once again!

[@bubblepins]

@@defonten Thanks for telling me! I didn't realize that scene file was jittering so badly. I was playing around with the parameters this morning and managed to reduce the jittering noise, but for some reason there is still a bit oscillation left. I posted an updated HIP file up along with a screenshot of the modified parameters I made on the blog. Sorry I ran out of time playing around with this scene, so I've reduced the jittering, but not completely removed it. I may revisit this scene in the future when I get more time. Hope this helps so far!

[@bryanng02]

Thank you so much for all your tutorials! Especially as a houdini beginner you have helped me get the grasp of it. Followed your tutorial and it works perfectly. Just a question! after the rbd deform it seems that the velocity attribute gets lost. Might there be a solution to bring it back?

[@bubblepins]

It's actually still there, drop down a unpack node and connect it to the 1st output, the Geometry output of the RBD solver. You can do the same thing to the proxy geometry as well. For some reason, it only works with the unpack node and the RBD unpack didn't work for me. Remember to put an asterick in the "Transfer Attributes" parameter in the Unpack node or choose the "v" attribute to transfer back out. Hope that helps!

[@bryanng02]

@@bubblepins thank you! it works but the velocity seems a little off not too sure why.

[@bubblepins]

@@bryanng02 Yeah I think the RBD Deform Pieces does something funny to the pieces. You can try this instead, put down an assemble node to repack the blast pieces and put down a point velocity node to recalculate the velocity for each blast piece. Then finally unpack it again and remember to transfer the v back out. See if that helps!

[@AwakeningAnimations]

Hey :) at 12:45 your video jumps back to something you showed earlier in the video and its back to normal at about 16:30 :) Thanks for the cool videos, they help alot!!

[@AwakeningAnimations]

Sorr y i only read the comment of someone else saying the same thing. It really seems like it restarts from a certain point as you redo some steps done earlier like moving the rbd constraint properties before the rbdconvertconstraints node :)

[@bubblepins]

@@AwakeningAnimations Sorry everyone! I think this was a miss on my part on editing. I think it could have been done better. Thanks for the feedback, it'll help me improve for the next videos!

[@jonasmortensen1252]

How do you make the ball collide with the wall if the wall was a voronoi fracture

[@bubblepins]

Replace the rbdmaterialfracture nodes with the voronoi results. You also need an unique name for each fractured piece, but the voronoi fracture node should do that automatically for you now since Houdini 17. Then plug that into the rbdconstraints, but you'll need a rbd constraint from rules or rbd constraint from lines or something to recreate the constraints. This should allow you to feed in your own fracturing into the RBD Tools. Hope that helps! You can also check out my other video on how to manually create glue constraints, but it uses the old dopnet way. kzbin.info/www/bejne/pGGrZIGDZaqAq8k

[@jonasmortensen1252]

@@bubblepins Thank you it worked!! but now my Tower/building is acting like an object instead of staying on the ground, so if the balls hits it, it goes flying off

[@bubblepins]

@@jonasmortensen1252 Double check if the constraints are created. In the rbd constraint from rules or rbd constraint from lines or whichever rbd constraint node you used, there should be a color option to view the constraints in the viewport. Drop down a null node and connect it to the middle RBD chain nodes (that's the constraint output of the RBD chains). And you should be able to see the constraints in the viewport. Hope that helps!

[@bijudhanapalan2982]

Thank you so much for the wonderful tutorial!

[@bubblepins]

Thanks so much for watching!

[@Fakepilot]

Great tutorial! I have been doing a few sims with this before, we are working with RBD now at Lost Boys FX school. If we follow this though, the deforming metal pieces continues to vibrate and does not stop. I had to do a VEXpression in the constraints, adding a i@timer++ and if statement to change the constraint into a Glue with -1 strength to kind of freeze it. Do you have any other solutions for that? I would have liked a more of an ease-out motion to my solution, at the moment it freezes after the timer is set. Gives it a bit of a stiff look...

[@bubblepins]

I had a similar issue with guided sims with RBD Tools when I had the strength of the guide set too high. So my guess would be a couple of forces are fighting for power. Do you have multiple forces acting on the objects? Like gravity and maybe something else? And this happens a lot when the object is too small, like less than 1 Houdini unit.

[@Fakepilot]

@@bubblepins Many times, changing the global world scale in advanced tab to like 10 or even a 100, helps a lot with making smaller pieces wiggle. At times, even jumping into the RBD Bullet Solver and changing the padding of the geometry to 0.

[@bubblepins]

@@Fakepilot I usually add a bit of padding to the collision geo unless its very close, then I would make it 0. Have you tried Convex Hull vs Concave? But it would take a lot longer to compute. I'm not sure if that is contributing to the vibrations

[@ericprochnow7584]

@Fake Pilot got into the same trouble with my sim... any way that you can share your vex code with us :) ?

[@ldr1709]

Thanks for the tutorial! Is there any way I can remove the wobble around the torn edges? I think freezing the frame by timeshift node can be a workaround for a single effect but what if there're more effects followed by already?

[@bubblepins]

Are you referring to the wobbling done by the RBD Deform pieces node? If so, I know what you mean, that node is very sensitive. THere's no magic way to get it, it's one of those things where you gotta play around with the parameter values to find the sweet spot. Hope that helps!

[@ldr1709]

@@bubblepins Thanks for the reply. Actually, the wobble was already present before the RBD deform node and it seemed like it just moved onto the deform node. When I tried other values in the RBD constraint property node I could decrease the wobble in some degree but it'd never gone away. Could there be a way to remove it 100%??

[@bubblepins]

@@ldr1709 There's no sure way, it's all about finding that sweet spot. But I hear you, I felt the same when I first used the RBD Deform and RBD connected faces nodes, they are all based on probability of how far the pieces are located. You'll have a higher chance of success with smaller movements between the pieces, maybe try using higher constraint values to hold the broken pieces tighter so they remain closer when broken. This will help if the constraints are on the edges. My theory is that when the pieces break and when you have some pieces broken but still hanging, hopefully those pieces will be close enough for the RBD Deform to perform better. Hope that helps!

[@0x384c0]

Do not disable "Apply Constraint Properties" in "RBD Material Fracture" node. In some versions of Houdini this might lead to loss if the attribute "constraint_type" and broken simulation.

[@bubblepins]

You make a good point. This video is a little dated, I am doing a more updated series of RBD nodes in Houdini in my new Cinematic Destruction mini-series that currently ongoing: kzbin.info/aero/PLqovuMX-teVMhkAd5dCfUI17Api5_YaPO You can disable the "Apply Constraint Properties" in RBD Material Fracture, but you just need to add the constraint attribute data back in afterwards. You can drop down a RBD Constraint Properties node after. The RBD Material Fracture node will create the Constraint poly lines for you automatically, which comes in handy, but if you wanted to create that yourself manually, then you need to drop down a RBD Constraint from Rules to create the polylines and RBD Constraint Properties to fill in the constraint data. Hop e this helps!

[@jiyongshin1910]

Awesome! Thanks a lot for the great video!

[@bubblepins]

Thanks!

[@StephaneSOUBIRAN]

Thank you !

[@alphaillusion4541]

It's starting to feel like cheating! 😍

[@bubblepins]

It gets better, the Banana Splits in RBD tools is so easy to get very nice results kzbin.info/www/bejne/manZdpKhp8atqbc

[@MAYA-je2dy]

thanks

[@bubblepins]

Thanks for watching!

[@MAYA-je2dy]

I love you

[@tariq0513]

This tutorial repeats itself at 12:42. It gets back on track at 16:28. Hope this helps people.

[@bubblepins]

LOL It's actually not repeating, but I struggled to find a way to explain that part and I think I just kept ranting on and trying to explain it differently, but the issue is I kept using the same words to describe it. That was a hard part to explain. I hope the small clips in the corner help clarify that part.

[@kingbach8796]

The tutorial repeating two times

[@bubblepins]

LOL You're not the first to say that about this tutorial, sorry! I sometimes rant on and on about a particular thing and I may said repetitive at times. I believe I have improved on this a bit over time as I create more videos, but the older videos I have done are set in stone.

[@sanjaysaho9366]

vedi is too long !!.

[@volnovhuesos6267]

Good result, but it's a sidefx example scene. Maybe that's why It’s starting to feel like cheating)

[@bubblepins]

I didn't use the SideFX example, but I think you're referring to the guided sim axe slashing clip. Yeah I saw it on SideFX's H18 reel and I thought it was just soooo cool. I have a guided sim video tutorial still in the works. I hope I can release it in the next couple of weeks. THanks for watching!