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## Popular Content

Showing most liked content on 06/26/2019 in all areas

1. 2 points

## Q: Building Gas Fields, Masks, Custom Forces

Hi, the mentioned masterclass is probably this: https://vimeo.com/42988999 I also like this tutorial: https://vimeo.com/119694897 Matt Estela has great tutorials: http://www.tokeru.com/cgwiki/index.php?title=HoudiniDops# http://www.tokeru.com/cgwiki/index.php?title=Smoke_and_Pyro I don't know if there is any new video tutorial, which describes the low-level principles. I learn by digging into the "shelf" solutions https://forums.odforce.net/topic/41800-gas-analysis/?do=findComment&comment=199863 https://forums.odforce.net/topic/42101-how-do-pyro-collisions-work/?do=findComment&comment=201007 Btw, when I am digging, I use this script "Find all parms referencing this parm". http://lex.ikoon.cz/find-all-parms-referencing-this-parm/ Here is an attachment, microsolvers_dev.rar with lots of experiments, just for an inspiration. Unfortunately lots of it is outdated (it is from the year 2011) https://forums.odforce.net/topic/13748-learning-microsolvers/?do=findComment&comment=101666
2. 2 points

## Q: Building Gas Fields, Masks, Custom Forces

Gas match field will let you create a new field and gas analysis will do a specific calculation, such as find the gradient or curvature. It's similar to the vdb analysis. Then gas calculate lets you do math operations, such as combining fields by adding or multiplying, etc. So if you had a FLIP sim, you could use a gas match field to create a new field, using the flip surface field as reference. Then you could calculate the gradient of the surface, and store it in that newly created field. Make sure to pick the right class of field for the new field, based on the operation you'll do with the gas analysis. Ie: to store a gradient calculation, it needs to be vector. Now you have a vector field, based on the gradient of the flip surface. You can use a gas calculate or gas linear combination (preferable for simple operations) to add that field to vel. Also, there's a masterclass called 'building fluid solvers" or something like that. definitely worth checking out.
3. 1 point

## Matrix component

https://www.sidefx.com/docs/houdini/vex/lang.html#dot-operator
4. 1 point

## Q: Building Gas Fields, Masks, Custom Forces

Hoping this topic picks up and more people engage in the conversation as well @ikoon That's interesting, haven't really been looking into vortex confinement too much so seeing this is encouraging enough to try and dissect it later. I'm guessing a\ll that (curl, grad,...) is essentially a representation of Rotation, Magnitude, Direction and then normalization in a simulation, correct me if I'm wrong. Been watching Khan videos on Gradients and Curl yesterday, really wish I found his content earlier, loads of gems right there. The examples from 2011 are still quite relevant in H16.5, all opens up normally and I did have a quick peek just now, so recommending it to anyone learning like me.
5. 1 point

## Q: Building Gas Fields, Masks, Custom Forces

Hi char, I would also like to know more about these deep things, so I hope other users will also contribute. My know-how is unfortunately not enough to explain these things. But if you have time and mood to "dig", then the gasvortexconfinement is really nice combination of Gas Match Fields, Analysis (Curl then Length then Gradient, then Normalize) and then Gas Cross, Gas Combinations, Gas VOP. It "applies" calculated result to the vel. From the docs about gasvortexconfinement: The Gas Vortex Confinement DOP applies vortex confinement to a velocity field. This is a force which amplifies existing vortices with the intent of undoing the diffusion that occurs during the diffusion stages of the fluid solver. You can also look at videos from 3Blue1Brown or Khan Academy, so you know how these nodes together "find" and amplify the Vortex direction: https://www.khanacademy.org/math/multivariable-calculus/multivariable-derivatives/curl-grant-videos/v/2d-curl-intuition https://www.khanacademy.org/math/multivariable-calculus/multivariable-derivatives/curl-grant-videos/v/3d-curl-intuition-part-1
6. 1 point

## Animation workflow

Other than the ones on the SideFX website I have no idea. Or you could look at the built in rigs too. In the object context theres 3, Simple Biped, Simple Fe/male, Toon Character. They'll all be slightly different, as will the rig you create from the Rigging Series (6).
7. 1 point

## Mouse causing hand wrist pain

@caskal with regards to scrolling the ladders, you could switch your settings so that the lowest button on your pen is a middle click, and your upper button is a right click. This way you have access to all 3 clicks (gently tab your pen on the table is a left click). this allows you to navigate houdinis interface just with the pen.
8. 1 point

## Houdini 18 Wishlist

what if the self buttons were creating DOP setups inside one SOP network instead of having a Geometry node, a DOP network for simulation and another Geometry node to import the data and save to disk. It makes much more sense to see the data flow from top to bottom in one network without having to jump to different levels for no reason. maybe it's just me... grains.hipnc
9. 1 point

## Houdini 18 Wishlist

an escape button, which stop the cooking INSTANTLY. sometimes i (and i know others as well) switch up the copy node inputs and run out of ram.
10. 1 point

## Generate Text File out of Houdini

1. Add new PythonModule to Scripts tab in Type Properties window. 2. Define your dump function. def dump(): # Retrieve values. geo = hou.pwd().geometry() data = geo.stringAttribValue('my_attrib') # Write on disk. path = '\$HIP/attribute_dump.txt' path = hou.expandString(path) # Expand Houdini variables. with open(path, 'w') as f: f.write(data) 3. Add new Button parameter and choose Python in the callback language. Then enter the callback like this: kwargs['node'].hdaModule().dump() Here is a bit more complex examples with vector arrays: attribute_dump.hipnc attribute_dump_numpy.hipnc (surprisingly for me, slower)
11. 1 point

## Learning microsolvers

Christmas has come early :-) http://robotika.com....solvers_dev.rar
12. 1 point

## Learning microsolvers

Higher speed will only give new mikrosolvers(HDK) with more optimized algorithms. But you can get a lot of different custom effects, or a small acceleration of the standard model, by removing some of the additions. I couple of years ago studied the effects of these guys, the projects were made for h10. http://dl.dropbox.com/u/4265149/microsolvers%20dev.rar
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