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Differential curve growth


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Oh yeah, that's cool. And I love me some Lindsey Stirling. :D

How did you setup the contract/expand thingie at 0:52-1:03..? I played around with contractions when I was knee deep in these setups but I never got anything good working.

I had also an idea to have some parts contracting and others expanding, and with some noise on the point positions, get the pattern move on the surface like from undercurrents. But I kinda got stuck before I had to move onto other RnD...

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Honestly, I have no idea why it does that, but I figured out how to work with it, so I was able to use it.  The only part that should be animating the growth motion.  What I am animating over the whole thing is just the final multiplication for the force, but when it approaches 0 it begins contracting.  I didn't change the system itself from the previous file I posted, so maybe you can figure out what is doing it in there.  Please share if you figure it out.

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Love this thread. Thanks everyone for posting your files, really interesting. I only had a couple minutes to play with this at work but here is a 3D mesh version. You don't get quite the interesting shapes we've seen here but I am hoping someone can do something with it from here. Literally just using remeshing instead of resampling. Tried putting points in the volume to avoid intersections but the shapes are even less interesting...





Edited by stevegh
wrong file
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  • 2 weeks later...
  • 1 month later...

Just wanted to post a variant of the very first setup using a per segment resampling rather than resampling the whole line, so the parts moving gets an extra push which yields a bit more "oily" look to it. I was using the per segment resampling for a completely different thing when I came to think about testing it with this differential line setup. :)


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After 20 years of CG I'm finally learning Houdini - most fun I ever had with a software. ;-)

Followed the Entagma Tutorial (thanks guys!) and went further from there to see if I can make the growth avoid certain areas. I used a black and white image mapped to the geometry and scaled the pscale attribute with it to make the lines "stop" at the borders. Leads to an interesting effect when rendering, as if the slightly overlapping areas were fading out.




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  • 3 weeks later...

Looking at it I come back to something I played around with but never got going (-well), that's contracting lines. 

Edit - LOL, actually wasn't very complicated, as the curve resamples, if you start pushing it in one direction, it'll downres itself into oblivion. :D


Edited by Farmfield
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  • Marc changed the title to Differential curve growth

What an awesome and fun thread. Thanks to everyone for sharing and a big thanks to the guys at Entagma. I took their setup and modified it a bit to hold the shape of the starting geometry better.

There are some issues when Selective Remeshing (remeshing by group) is enabled. Every once in a while the Remesh SOP will generate a model with patches of inverted normals. Haven't figured out a clean way of dealing with that as the Facet SOP and PolyDoctor don't work a hundred percent of the time.



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