All Activity

Is there a way to access the world bounding box or extantHints within the Karma material builder? I'd like to use the scale of an asset to drive the scale of the texture being applied to it. I can create an attribute in SOPs to drive the scale, but the bounding box is sitting right there and it seems like I should be able to grab it, but I've tried all the variations I can think of and can't seem to access it.

That's fascinating, never would have thought to try it but now I think about it, vops does have density plugged into density out by default! Thanks!

It works when you do some operation on the volume. Simply adding @density = @density; is enough. addpoint(0, @P); @density = @density; // Telling Houdini that it should care about this volume My guess is that the wrangle skips processing any volume that isn't referenced ? I would be curious to learn about the intricacies, if someone knows.

In a volumevop I can generate as many points as I want, either using the 'add point' vop node or using 'addpoint()' in a snippet. However, using 'addpoint()' in a volumewrangle results in no points. I'm wondering, what's the reason for the difference in behaviour? I'm guessing there's something I don't understand about how the two work.

Nice Richard - looks interesting, I'll try these ideas out. For me actually minimal mixing is ideal, the colours should stay nicely separated. Damping down the velocity is a good plan. At the moment I'm using a mono-rgb at the end with tight-spaced knots to give me the different shades. Not exactly what I was after, but it's looking promising.

I was playing around with this idea for fluvial texturing of terrains. You can get an idea of how I got on here. https://www.youtube.com/watch?v=3IWnBREVup0&t=13s I would say it depends on the look you are going for. As you mentioned cops flow tends towards tendrils swirls. pic02 I didnt end up putting it in the video above but what can help to soften these off is to do a distort in the flow block, if you use the same velocity you will be distorting the flow at each timestep. This ends up giving you softer transistions between areas by basically blurring in a direction at each step. I think I also added a streak blur after the distort again with the same velocity. In my case for terrains I only care about the end result, so no animated mixing, just the final texture. If you want proper mixing, where one color nicely diffuses and mixes with another color then I dont think that the current flow block does this. There is a pyro color smoke example (type pyro configure color smoke) which does some nicer mixing which might be worth a shot.

Hi - looking at ways to make this sort of effect, where separated colours run into eachother. It's fluid... but I'm thinking that a full flip fluid sim is the wrong way to go about this, especially as it'll be largely flat drips that are running into eachother - the resoultion & point counts needed would be super-tedious, and probably overkill. The flow-thing in Copernicus seems promising, but I'm having trouble keeping it from forming the super-tight spirals and mushroom-y swirls. So.... I thought I'd ask here! Any advice welcome :-)

Here's the hip. I didn't have any constraints because I don't know how to set them up properly in my scene BreakChainHow.hiplc

Can you share what you got? there are a few ways to make that work. If you setup constraints, you can delete them by different types of methods.

Any tips on how to break a chain? I currently have an rbd sim of a chain that is being pulled and I want to break it at some point but I don't know how. I converted my chain to vdb spheres btw.

Small update on minimal surfaces using the poisson equation and some more modern nodes. minimal_surface.hip

Very cool solution--thanks!

How about instancetest_02.hipnc

What’s New in the Houdini AI Assistant v0.1.5 Multi-provider AI support: OpenAI (GPT) Anthropic (Claude) DeepSeek Houdini AI Assistant: https://rart.gumroad.com/l/HoudiniAIAssistant Local AI support: run models locally via LM Studio or Ollama (great for privacy/offline workflows). Prompt editing: you can now edit in the UI. MoE for HDA Architect: a Mixture-of-Experts workflow to improve HDA generation quality and consistency. Thinking level controls: select the thinking level for both Scene Analyst and HDA Architect. Easier installation: smoother setup with clearer guidance and fewer manual steps. Improved international input (Qt6 only for now): better support for Japanese, Chinese, and Korean text input. Qt5 support is coming later. Houdini AI Assistant: https://rart.gumroad.com/l/HoudiniAIAssistant

I'm doing the whole emit-vellum-objects-and-then-point-deform-the-hires-even-though-because-it-was-emitted-it's-not-a-simple-plug-and-play thing. I've done this before but have completely brainfarted how I did it and Frankensteining a few different tutorials is giving me something weird. I'm not doing variants, it's just one object, but the number emitted per frame varies. If anyone can help point out the Stupid Wrong Thing I'm Doing here it would be greatly appreciated. I'm guessing it's a packing and/or naming thing along the way. (Also, I noticed that the solver sop double up the instances on the first frame.) instancetest_01.hiplc

@ellietarrant me just playing," more like some Strange Crystal" need tweaking, with Rock Shader you can find (Please investigate and in the Future post file with your approach also) that Shader here https://www.sidefx.com/tutorials/as-cold-as-icewith-copernicus/

Currently I have a growing frost simulation where I am just using a general glass shader that I access through the material linker but it doesn't give the frosted or sparkly effect that snow crystals have. I have some experience using the material X and karma material builder, and have recently looked in the principled shader, but im unsure which would work best for this ! Any help would be greatly appreciated!

In case anyone else in the world ever needs this, I found the answer--"targetw" has to be included in the constraint attributes to be overridden.

So I know to get the wheels going using the RBD car rig and the bullet solver you have to override motor_target, goal_twist_axis, and goal_up_axis in the constraints tab of the bullet solver (SOP level). That does the trick for speed and steer, but the brakes still aren't working. What do I need to override for aggressive braking? (I'm using two different car rigs--one for a semi, the other for a trailer, both packed and merged.)

Thank you!

A bit late, but maybe it helps someone else: You can also just give your initial particles an attribute with full numbers only (0,1,2...), then have flip interpolate this for reseeded particles (list under attributes to interpolate in the reseeding tab). This means particles with any number that is not a full number (1.01,5.92...) is 99.9% gonna be a reseeded particle.

@ellietarrant + file on Github https://github.com/jhorikawa/HoudiniHowtos/tree/master

Yeah! so far i have something like this, but I can't seem to figure out the branching for the ice https://youtu.be/EajYgwiNt4g frost.karmarendersettings.0073.exr

If you can share the .hip file, I think I could give you more detailed advice, but if you search for things like “VDB Growth” you should be able to find several tutorials. https://www.youtube.com/watch?v=eBH4MFU8V2Q