Control Destruction with Force Fields in Houdini Simulations (Rigid Body Dynamics RBD)

[@ignitee_]

i payed for a full destruction course, and i didn't understand anything in forces part. So that's why im here. And look, you teaching and explaining much better then a guy from a course. And you even explaining how does it work, why does it work and showing some marks on a video. That's an amazing piece of content. Your channel is golden, I subbed. Thank you for what you're doing :)

[@bubblepins]

Thanks for the awesome comment!

[@chrisjang3209]

This tutorial is greatly helpful! Thanks!! Plus, your pronunciation is so good to hear for foreigner like me :)

[@bubblepins]

Thanks so much!

[@ElSeñorDeLosResúmenes]

I just understand a little english but your videos are amazing. It's easy to understand

[@bubblepins]

Thanks for watching!

[@ericperreault8889]

another awesome tutorial, your explanations are so clear and I'm learning so much. My speed also improved a lot cause you take the time to go over the steps many times to the point where I anticipate where it's going and I'm taking more and more initiative on my own...and I've been learning houdini for only a few weeks and I feel more and more confident and more importantly I understand what I do and why. Thank you so much for all that knowledge you're sharing with us...and I know it's been said but I really like hearing your voice it's really nice but more importantly you make sure to not talk too fast, I mean English is my second language and don't get me wrong I can handle fast talk but the pace for these tutorials is perfect :) thank you so much

[@bubblepins]

Thank you for the awesome comment!!

[@wesselvanwegen5872]

Thank you very much for the clear explaination. As many already mentioned, this is a great tutorial with a lot of attention to actually getting to understand this as opposed to bashing in values from screen. Thanks a lot!

[@bubblepins]

Thanks for the comment!

[@danilodelucio]

Brilliant, I have no words to describe my happiness in learning this one. I faced this setup a lot of times in the past, and NEVER someone explained with too many details as you. I was feeling so stupid for not understanding and now I can tell you with certainty that I've learned. Thank you so much, so anxious to see how to break constraints (the link is already separated here lol). Thank youuu!!!

[@bubblepins]

Thanks so much for the awesome comment!! Hope you'll like the next part video just as much!

[@zunchomultimedia]

Beautiful voice and great tutorial! Thank you.

[@bubblepins]

Thanks for the awesome comment!

[@ayanbanerjee5613]

very helpful. Love the way you show how to do all this thing. Thanks.

[@bubblepins]

Thanks for watching!

[@UltimaOne984]

Damn it might be the answer to an enormous issue I ran into Yesterday. You're so good on rbds damn...

[@bubblepins]

Thanks for the comment! I'm super happy my videos are helping!

[@joshwolowhatever]

this is one of the best houdini toutorials ive seen, and im really glad i found it, i will be watching more of your stuff for sure, im in college right now for vfx and would love a chance to talk with you more about houdini if you have the chance.

[@bubblepins]

Sure, I respond to messages quite quickly, I love chatting about Houdini or anything 3D related. It doesn't have to be a question, but if you do have one, I will always try my best to answer it! Happy Houdini-ing!

[@joshwolowhatever]

@@bubblepins cool, thanks. i was just wondering if there was a way to get forces to interact with an object that i set up with a bullet solver?

[@bubblepins]

@@joshwolowhatever Someone asked a similar question before and I made this blog post to describe how to direct forces to a specific object within the same dopnet simulation. bubblepins.com/blog/controlling-force-field-for-specific-geometry-in-destruction-simulations-in-houdini?rq=forces See if this helps!

[@joshwolowhatever]

@@bubblepins thank youuu

[@joshwolowhatever]

@@bubblepins I'm also curious, how long have you been doing houdini, you seem pretty skilled in it and I'm trying to gage how long till I might get better

[@MABprodrennes]

Thank you so much for sharing your knowledge ! I start on Houdini and it helps A LOT !

[@bubblepins]

Thanks for watching!

[@ananan4469]

Your video is always great :)

[@bubblepins]

Thank you! You're always the first to watch!

[@vazelevz]

This vector thing is like: Come on .. don't you mean my math lessons weren't useless )

[@bubblepins]

I had the same feeling when I was doing this force field thing. It was like, finally my trigonometry math comes in handy for something!

[@cerealnpixels]

Great video and very helpful, is there a way to apply the force to one specific object? I made this rbd car simulation and I'm trying to shatter just the glass, but the force I'm applying is destroying everything in the simulation

[@bubblepins]

I actually covered this in a blog post: bubblepins.com/blog/controlling-force-field-for-specific-geometry-in-destruction-simulations-in-houdini?rq=destruction This shows how to do it using a dopnet. I will soon make a new tutorial on this with the newer rbd sop tools!

[@cerealnpixels]

@@bubblepins Thank you, much appreciated

[@pavelpetrikor]

Thanks! How to force (vortex) fractured RBD?

[@bubblepins]

You create your Tornado Velocity vector field and feed it into the dopnet by using the popadvectbyvolume node. For a more detailed step by step tutorial, I actually made a Members-Only video on Custom Velocity for an RBD Tornado scene: bubblepins.com/membership/tornado-motion-using-custom-velocity-fields-live-stream Hope that helps!

[@gwynbleidd9000]

I’m still noob in Houdini, but instead creating this vector pointing outwards, could we just in our sphere add normal node, and then plug normal attribute in attribute vop to force attribute?

[@bubblepins]

Yeah I guess you could do that... lol. Add the Normal's to points though if you still want to follow this tutorial, because I use nearpoint node inside the geometry vop to find the closest force field point. It doesn't save you much nodes, because the other stuff in the video still needs to be done to get the force field going. But this is a good idea!

[@chxrveyvfx6046]

I actually have an interesting idea regarding this (just using my uni account -- may recognise the name similarity) But couldn't this be applied to pyro objects to if geometry was used as a template and the attribute was created before the pyro was inputted essentially? As you would still get the same attributes what can effect the packed geometry but just from a collision impact point of view? If that makes sense?

[@bubblepins]

Yup, it definitely can. The "Force Field" I refer to in this video is a vector field that is being applied to the force of the RBD pieces. But it's just a vector field, so it can be applied to anything that is another vector. Like the velocity of gas, or even use it to drive noise. If you want it to drive gas, you'll need to turn the vector field (aka "Force field") into a volume using the volumefromattribute node and use a volume source to feed it into the sim. Hope that helps!

[@chxrveyvfx6046]

@@bubblepins alright thank you!, trying to sort it out now never used the volume from attribute node before so its a little tricky

[@enniomarin9134]

Hello, i am using your tutorial (which is great by the way) to progress on one of my projects. As i am a massive beginner i don't really grasp the logic of the attributes yet. But i noticed that my values are very different from yours to get correct results, for example i have to set my glue to 0.001 for it to not hold to much or the multiplier for my force cant go above 10 or else its way to strong. Would you have any pointers at so why this is happening? Thank you in advance. PS i am using a material fracture not directly a voronoi and my object is a stature that's around 1.5 meters high by 2 meters wide.

[@bubblepins]

Hi, I had the exact same problem when I started out using the destruction constraints in Houdini. It does take a lot of trial and error to get it working. Your glue of 0.001 seems very weak, it may not hold against gravity. So even if you don't have any forces acting on it, it may crumble just due to the gravity. I would suggest that you get a structure standing with gravity while the sim plays for a few frames. Let's say 50 frames. After you find a glue strength value that can stand up against just gravity, then try to lower this glue strength value, this is to ensure you have the lowest glue strength that will stand against gravity. Then write down the glue strength value, or mark it down as a HOudini note in the network. After that, you can add other forces to knock it down to make it more complex, and you can adjust the glue strength accordingly. I have another video describing this process in another previous video (link is timestamped when I demonstrate this process): kzbin.info/www/bejne/ppu1naSgotR4hck Hope this helps!

[@enniomarin9134]

@@bubblepins Hey thank you so much for the reply i have watched your other tutorials and managed to get a working sims thanks to them. Although it still needs some tweaks. Thank you for the tips and the great content have a nice day

[@hemakshgandhi]

Hey! Thanks for another amazing video! Although can I ask, in the beginning, while positioning the sphere why did you have to select it by going into the 3D Connected Geometry mode? Wouldn't it be easier if you just used the transform node? Does it have some effect later on or is it just a personal choice?

[@bubblepins]

Good eye! there is actually a reason for that! lol One reason is to give more exposure to the audience with the 3d viewport functions, because that was one of the things I personally struggled with Houdini at the beginning. The second reason which is the main reason, if I drop down a transform node, the gizmo usually appears at the origin point, which in this particular video doesn't really matter, because the sphere starts in the origin. But what if the sphere was initially moved over and when I drop down the transform node it just unslightly because the gizmo is in the origin and the sphere is moved somewhere else. If you use the edit node, the gizmo will always be centered in the selected geometry, which I kind of like. The rest below describes about the gizmo pivot point of the transform node, which may overwhelm if you already knew about it: You can't really see in this video, because the sphere initially in the center to begin with, but try moving the sphere to a different position and drop down a transform node, the gizmo appears in the origin and not at the center of the selected geometry. Another side tracked point is that you can actually change the transform node pivot point (where the gizmo appears). Select the transform node, mouse over 3D viewport, press the ' key, that's the apostrophe and the gizmo changes a little bit. This is actually the pivot point of the transform node, which changes how stuff will rotate in the transform node. For example, if you want to rotate around something, like a camera rotate around a character doing a turn around. This was actually a longer answer than I thought. I might make a blog post on this describing the gizmo ui a little bit more with pictures for clarity. I feel like describing in words might not be as great. I'll post a link back to this comment a little later when it's published. Hope this all helps!

[@hemakshgandhi]

@@bubblepins I think I got some of it but not everything lol :P either way I'd love to read the blog post with you explaining the same... Let me know when you make that blog by posting the link to it in the replies or something?

[@bubblepins]

@@hemakshgandhi Yeah I'll reply to this last message, I'm hoping will trigger a notification on youtube.

[@bubblepins]

@@hemakshgandhi Hi, here's the blog post, I hope this helps! bubblepins.com/blog/houdini-transform-node-vs-edit-node-ui-tips

[@hemakshgandhi]

@@bubblepins Lol no, it didn't trigger a notification. Anyway I looked at the blog and it's much more clear to me now. Thanks a lot! Also could you maybe make tutorials teaching us a specific effect? Like tornadoes, car explosions with debris flying off, turning on a lighter, blood splatter or lightning?

[@10jobstudio]

hey, teacher! i can do almost it but, After adding noise in inner primitive, I want to do the primitive work, but if I use the pack, everything disappears. Noise uses the rbd object, so the force does not apply. What should I do when this happens?

[@bubblepins]

I usually use the Assemble node and check the "Create packed geometry" there. Because the pack node puts the entire geometry into 1 packed point. But I think you have a fractured geometry, so you have many pieces and you want to pack each piece to result in many packed points. The Assemble node will do both for you. If you want to use the pack node, you need to name each individual fractured piece with a unique name first on the primitive. Then the pack node has a "Name Attribute" parameter that you can specify how to identify the pieces to pack. But again all this is done automatically for you by the Assemble node. Hope this helps!

[@10jobstudio]

I tried simulations using Rbd factored obj dop. But only gravity was executed. The external force, i.e. geometry shop and the attribute vop, which is force only in the spheres, were ignored. So, teacher... Should I use another rbd obj dop or something I missed?

[@bubblepins]

@@10jobstudio If you pack the geo, then in the dopnet you need to use rbd packed object. I have a more detailed explanation on packing geo in another video, this link is timestamped to where I begin talking about packed geo 18 : 10 kzbin.info/www/bejne/qn-WqGasi7mho68 But I think you're already really close, you might not even need to watch it. I'm actually surprised the gravity even worked, because I would have expected an error since the rbd fractured object node won't recognize packed geo. And double check inside your geometry vop that it's applying to the force, you can even try overwriting the force with an extremely large number just for debugging. I demonstrate some debugging techniques starting at 14:48 in this video: kzbin.info/www/bejne/hnmQeKGmdsZ_nqs Use the visualizer on the 3d viewport and setup a marker so if it's set up properly you will at least see some arrows on the 3d viewport, remember to cook a couple of frames to see the arrows, because the forces need to be calculated by the solver. Next if the pieces aren't moving, like in this video, I show how to increase the strength of the forces and decrease the glue strength to help it, just for debugging to see if the pieces are moving in the right direction. And I start adjust the numbers to get the effect I need. Hope this helps!

[@10jobstudio]

Thank you very much. The error appears in the rbd facture dop. So I don't understand how to solve it:( sorry

[@bubblepins]

@@10jobstudio Are you still packing the geometry with an assembly node? If so you need to replace the RBD fracture object. You need to replace it with an RBD packed object inside the dopnet.

[@marcocheng3729]

I think any force field in Houdini (bullet) will not break the constraint, you have to break it manually (constraint solver). The force in your case just drag the entire geometry and break because of the collision.

[@sanchezAlvarez]

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