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Volumes 101: Curvature Driven Growth (Patreon)

Published:
2017-10-26 12:20:24
Imported:
2026-06
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Videos

Content

Let's combine our curvature measurements with volume advection to form the base of a rather versatile setup for organic (and sometimes a bit disgusting looking) growth.

Files

Previews only

Volumes 101 pt. 10: Curvature Driven Growth

Comments

hadrien ledieu

Just a quick question. The bind export is set to float. Isn't it supposed to be a vector? it's the result of a vector (gradient) multiply by a scalar (curvature). Plus it goes in a vdbAdvect which requires a vector.

entagma
>>10983800

Hi Hadrien, what Houdini does in this case is infer the data type to export from the incoming data type, which can also be seen in the bind export's input port color changing from blue (float) to green (vec3) :) Cheers, Mo

simo leo

Hello there, I know it could sound like a stupid question but I've noticed that if I change/swap the input of the multiply "operator" ( inside the Volume Vop, just before the Bind export) it doesn't work. This is quite odd to me since that 3x6 is equal of 6x3 ( Commutative Property of Multiplication). Might be a bug? Or did I miss something?

entagma
>>12217681

Hi Simon, Houdini tries to infer the data type of your operation by looking at the first slot of your multiply VOP. If you swap both inputs on the multiply VOP, you will also change the data type of your multiplication from Vector (3 floats) to Float (one single float). So what the VOP will now return is a single float instead of a scaled vector. This can also be seen by the color of your output slot: green for vec3, blue'ish green for float. Cheers, Mo

simo leo

nice and clear , thank you so much!

Eric Sanderson

Are there any known VDB Analysis "Curvature" bugs as of Houdini 18.0.391? Ive scrutinized over every step all night yet advection yields no results when the curve analysis is involved. Even if trying to mult the raw grad output by the curve (where id expect drastic results)

paul silcox

Volume sample... that ones going to be really useful. Thanks!

Molnár Dániel köszi a könyvet, Rácz Zsuzsa koriget

I recreated this tutorial around 3 times, and I started to give up, becouse every time the whole mesh got inflated without any sophistication. I was like, shit, the curvature analysis isn't working... After around an hour of angry tweaking, I realised, in the vdb Gradient analysis node somehow is REALLY important that the given custom name is not "grad" (as the node's name), but "gradient". With grad, the whole mesh inflates. With gradient, everything works fine. Is it a embeded name?

entagma

Hey Dániel, good catch! I think the culprit in this case is the bind export node in the VolumeVOP, which we set up to export our result to a volume called "gradient". So in order for the VolumeVOP to be able to write back its results into the volume, it needs to have the same name that we set up in the bind export. If you want to name the volume differently, just make sure to set up your bind export accordingly :) Cheers, Mo