Differential curve growth

[Farmfield]

This is really cool... Looking to the very first part, I did a simple setup yesterday, trying to replicate it, but can't say I got very far before running into issues. The problem with the POP setup is it really wants to create the coral patterns - even using a polyframe to calculate outwards normals and using them to guide velocity outwards, you get to a point where is starts to fold into itself" and create those traditional differential curve type patterns... So perhaps something ti rethink - or perhaps someone here has an idea..?

Oh, and just generally, there's SOOO much friggin cool stuff in this video, I can barely watch without freaking out, wanting to try to replicate all of them, hehe...

 

Edited December 21, 2016 by Farmfield

[Dusmus]

Great thread guys, lot of stuff learned ! Thanks !

[trzanko]

Posted a thread on some tools, one of which is how to calculate the concave curvature of a mesh. I've used it to get some pretty cool differential growth results. It runs on points only so it's pretty fast.

Here's a link to the thread.

 

-Tighe

[Farmfield]

So funny, last thing I did last night was watch your Vimeo vid on this and as I was watching it, I got a notification that you posted the above. But yeah, really cool setup. I just love the gradient and curl direction, that's really helpful for some stuff.

Edited March 3, 2017 by Farmfield

[trzanko]

On 3/3/2017 at 8:17 AM, Farmfield said:

So funny, last thing I did last night was watch your Vimeo vid on this and as I was watching it, I got a notification that you posted the above. But yeah, really cool setup. I just love the gradient and curl direction, that's really helpful for some stuff.

haha that means the sharing is working

Happy to hear that you find the gradient and curl direction useful, mind if I ask what uses you've thought of for it? I developed this method when making grass patches and found that using it in tandem with curvature it lets you groom pretty easily, well at least give you a good starting point. 

The differential growth that can be made with the curvature is kind of a plus. 

Interested to hear all the different uses people can think of. 

-Tighe

[Farmfield]

I'm more thinking of the vectors, using them to drive stuff on surfaces in interesting ways, directability of particle effects, that kinda thing... Doing custom force setups is something I seem to return to quite often, so anything about generating vectors from input objects are potentially very useful.

[Sence3D]

On 2.6.2016 at 9:00 AM, Adam Ferestad said:

I have made another one for my final in my Procedural Modeling and Animation class... Let me know what you think.

 

 

On 21.4.2016 at 8:02 PM, Tesla's fan said:

poptest_2.hip

thanks for sharing this technique! i rebuild your setup in houdini 16 and it doesnt work somehow... i copied the exact same setup to build it myself and trying to understand the process but it just doesnt work nothing happens... can you help me?

 

thanks!

curve growth problem.hip

[Farmfield]

It's all about balancing up the values, your head was too small, your resample and repelling forces were out of sync - you gotta repel further than your resampling distance - etc...

And I'm still in love with this technique.

curve growth problem_FF.hipnc

[Sence3D]

thank you!! yea sorry im new to houdini and trying to learn it rn so forgive me

[Farmfield]

No problems. And I too started in POPs, learning Houdini, though looking back I should have spent more time in SOPs before I did that - POPs, well, DOPs overall, is just "work", sim'ing, tweaking, in a way, wasting time. Learning Houdini is all in SOPs, imo.

[Sence3D]

So i got it working now, but when i apply a polywire node it affects the pighead geometry, how can i avoid that? i just want it to affect the curves 

[mestela]

On the popnet, make sure the object mask specifies only the geo you want to export; it'll probably be *, meaning 'export all the things, including collision geo etc'. You probably want it to just be 'popobject1' if thats what your pop object is named.

 

 

[fablhaft]

Hey guys,

great forum. I'm also new to houdini, and I was wondering if anybody could help me. I'm really fascinated with the recursive growth but is there a way to use a vectorfield of an river or something like that. To drive the direction of growth?

The goal would be to have a river sim and a recursive growth happening at the same time. So the growth disturbs the river or water sim and due to that also its own growth direction.

I hope it sounds not to stupid but I really have no clue at the moment. 

 

thanks for any tips

[Farmfield]

Sure, as it's a particle system, any force will work, like something as easy as transferring velocities from a FLIP simulation to the differential curve setup in a SOP solver or alike - but that being said, I would guess it's going to be tricky to control. This particular setup is very happy at one specific conjunction of values and there it behaves very predictable in both 2D and 3D, but pushing it in other directions it either just stops doing much or it starts to behave very erratically. But try it out and post the results in the thread.  

[zinogino]

So much information here, just starting out learning H as well (moving away from Maya)

[fablhaft]

17 hours ago, Farmfield said:

Sure, as it's a particle system, any force will work, like something as easy as transferring velocities from a FLIP simulation to the differential curve setup in a SOP solver or alike - but that being said, I would guess it's going to be tricky to control. This particular setup is very happy at one specific conjunction of values and there it behaves very predictable in both 2D and 3D, but pushing it in other directions it either just stops doing much or it starts to behave very erratically. But try it out and post the results in the thread.  

Hello Farmfield, Thanks sound like good news, but unfortunately are my skills to weak to make that happen. Do you eventually have some other examples where I could look how someone did it? Or if you have any time left, would you please desribe it to me. You would help my a lot! And sorry if I'm annoying but I really have no clue And Yes If I have anything i will post it here.

[Farmfield]

Well, you won't learn anything from me or anyone else setting it up for you, because you are at the wrong place in regard to how far you have come in Houdini. And not saying that to be rude, I just want you to have the best angle of improving your Houdini skills.

So what you need to focus on is attributes and attribute transferring, because it's seriously the key to unlocking Houdini. Imo the best "mental approach" in Houdini is to look at it as there's only points (*) and whatever you need to do is about manipulating those points. You also need to think about what you need to manipulate the points. In this case we are working with particles, so any growth is movement and that's velocity. So you need to manipulate that. You do that either manipulating the actual velocity or adding a force. Force is basically additional velocity added over time. 

So what you'd need is a basic differential curve growth setup and a source for your influencing force. So for that source you need to generate velocities (if that's not already there, like it would be in another POP sim or FLIP). I haven't messed with the new ocean tools, though, so unsure if it generates surface direction vectors, but seeing the foam and such, I would guess it does and that's attribute values you can use for something like this.

When you got the differential curve setup you want to advect and the directional vectors you need to do it (likely a velocity vector) you can just set it up in a SOP solver in the POP sim, object merge in the source of the velocities and just use an attribute transfer to pipe it into a custom attribute on the POP object and then you'd just use a POP wrangle to add that attribute data onto the current velocities, either adding them to your velocity or using the force attribute, adding it over time.

And if none of this makes any sense, we're back to the first line in this post and you have a lot of more time to spend in SOPs getting to know and understand how Houdini works with attributes - because it will never be more straight forward than this in Houdini. This seriously is pretty basic stuff, hehe...

(* unless they are voxels, but kinda the same approach, either way)

[erbay]

Tried to recreate manvsmachine and mill line growth effect. If interest hip is in vimeo description.

https://vimeo.com/216659184

https://vimeo.com/216657273

Edited May 9, 2017 by erbay

[sjr]

Hey Folks,

This thread is such a good resource for Differential Growth experiments, I thought I'd add this one, from Martin Salfity's Behance site, for work done at Art&Graft

 

from here:

https://www.behance.net/gallery/47193587/Experiment-Number-2

Cheers,

Stu.

[jojoodforce]

Dear all, this thread just rocks, I've discovered recently houdini and I think it's really a beast of it's own. I generally work in biomedical illustration and I was searching for a technique to recreate and illustrate human kidney and glomeruli. At a fist glance they look quite a lot as a growth diffusion process but also a lsystem. I was thinking about growing "lines" inside spheres with diffusion process but I don't know if is possible to set a node for activating a lsystem at the same time. Any help would be appreciated also if anyone is interested in this topics I would be glad to talk about them.