# Differential curve growth

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hi there, new here! great thread.

i tried to clean the first solver posted here

tell me what you think

diffrenial_line_grow_A1.hipnc

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added some attraction and repulsion forces so it will fill up the volume.
still sometimes the line can escape the bounding object but hey! maybe someone here will fix it
if you will run it you will see the green parts indicate the point is being attracted to the surface and if it is red it is being repulsed by it

Edited by leohak
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Thanks for sharing the file I will try to use it for creating some organic stuff

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• 4 weeks later...
On 3/31/2016 at 5:57 AM, mestela said:

Ah, nice clean technique Yader, thanks!

(obscenely large gif, sorry)

Amazing! Thank you for taking the time to share.

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• 2 months later...

Just wanted to post this as an example of using this technique as foundation for something else. Scene file in the Vimeo description.

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• 3 weeks later...

Nice thread with interesting topic.

My two cents to this topic:

- solver which allows structure to separate grown parts from initial structure when some condition is met and continue to process those parts same way it processes starting structure.

In attached example I tried to keep things as simple as possible. The whole magic is inside solver inside for each loop, where shape is tested against conditions if physical distance between two points is small enough and there is more than K points on the shape in between them, separation occurs.  This example works in 2D but with this concept it can be extended to work in 3D space. Instead for searching if two points are close enough you search for 3 points which form triangle whose area is small enough but larger than zero.

Both examples are in the scene file

cheers

dgs.mp4

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Hmm, there's a slight weirdness going on in those clips so when I get time I'll put on a face mask, some rubber gloves, and investigate the mysteries of this organic compound.

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Since they are already cut to pieces don't forget a spoon

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• 4 weeks later...

Hey guys,

I very new to Houdini and was messing around with the differential line growth tutorial from Entagma.

Instead of using a single circle I used a copy and transform node to have that growth relative between multiple clones, then after the solver I want to translate each primitive on the z axis.

I have been able to achieve it manually but it's just the opposite of what houdini is cool for, so I tried the for each loop trying to translate each primitive by increment but it didn't work.

I'm sure it's very easy that I am missing because of my lack of knowledge but should be for sure piece of cake for most of you.

Cheers!

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That looks really cool, Jonas, and loops are tricky sometimes, depends on what you're trying to do, but post the scene file with the loop and we can see how you thought - and I'd love a scene file either way, that thing looks really cool...

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Here is the file, really nothing much more than the entagma tutorial.

I've only been able to duplicate a all the instances instead of 1 at a time

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Thanks, much appreciated. And just to be clear, I don't remember how Entagma set this up, I actually don't remember 90% of my own setups I posted on Vimeo, I have to go back and check all the time what the hell I did on one setup or another when people ask me how I thought, etc...

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Haha sorry for that, thanks for checking out!

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Oh, I forgot about this one, yeah, really simple, and gives a great behaviour.

And this is how you'd use the foreach for the copying.

diff_line_growth.FF.hiplc

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Awesome thanks so much!

I was pretty close, even though I'm not sure I've could have been able to figure it out.

May I ask the meaning of that expression?

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Man, it's really badly threaded, though, checking the performance monitor, the relax node isn't multithreaded so it'll just drag the whole thing to a crawl... I really would recommend setting this stuff up in POPs instead, using either the POP interact or the grain solver, it's just so much faster as they are multithreaded.

And what expression? In the transform? That will fetch the information for which iteration you are currently on which is a detail attribute of the node I pointed to.

Edited by Farmfield
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Yeah in the transform, that shows how limited is my knowledge. Thanks so much for your time I will dig more on this

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Yeah, it's a lot of fun and you can do really cool stuff. Here's a setup I'll go through in my upcoming course, whenever I'll get that out - but yeah, it's in the works.

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Super cool!!

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Ok now I'm trying to constrain the growth within a letter but also copy it over multiple scattered points on the letter. It seems to work fine except on the for each, it translates all primitives instead of having the 3 groups starting from the origin. I can't really visualize how I could achieve this, I tried to have the copy to points before the copy/transform but the scale is relative to the SOP centroid.

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