Deborah R. Fowler
Particles in Dynamics
Posted: 2013
Updated: Mar 8 2024
Particle Tips and Troubleshooting
Examples:
History:
Particles have been part of Houdini for a long time. They are now
fully integrated in dops and were once a separate solver. Why
mention this? To make sense of some of the now "older" posts and
example files.
Overview:
PDF version of my power point Lecture: Intro To Particle Dynamics here.
Tips for Particles in Dynamics
and the workflow
- turn on the display flag on or after the pop solver
- you must disconnect or bypass the pop to disable (or you can use the simulation button at the bottom right corner - the brain - to turn sims off)
To create a particles simulation you can
either create one from shelf tool (it will create an
AutoDopNetwork (a dopnetwork node) with a default setup
having gravity, attributes set to "Add to inherited velocity"
and Variance set to 1. You can also create a popnet inside of
sops by hitting tab and typing popnet (just a dopnet node inside
of sops).
In the shelf tool setup, you also have a geo
node that contains the particles. You can do the same thing in
sops by using a dop import node, or using the convenient object
merge tab on the dopnet node to bring out just your particles by
typing popobject in place of the * that is in the Object field.
There are many pop nodes - hit tab and type
pop to see the variety.
A few that I want to point out are:
- Curve Force tool - there is a curve force tool to make particles move along a path (we'll talk about the vops/vex way as well)
- Flocking tools
- following a leader (small exercise to try) here
In addition, you can manipulate your pops with
vex.
- Vexpressions - http://www.sidefx.com/docs/houdini19.5/dopparticles/vexpressions
- note that if the "Use VEXpressions" checkbox is off, the parameters use Houdini expression language, but values cannot vary per-particle. With it on, you can write VEX code snippets to evaluate on each particle at each time step.
-
Documentation on Vex snippets can be found here.
TIP: (use CTRL-ENTER to commit changes in the vex snippet window)
pre-made snippets are contained in the multi-line editor drop-down menu
Other Resources:
Steven
Knipping has some excellent tutorials on particles
Entagma also
has great resources
- one of my favorites to dig a bit deeper into pops is the Production Setup Walkthrough: Color Dust Explosion
Particles - Lesson 7 - Ari Danesh (H13)
Also there is an fx guide about H13 http://www.fxguide.com/quicktakes/side-effects-houdini-13-we-ask-them-about-their-fea/
And now fx guide about H14 http://www.fxguide.com/quicktakes/houdini-14-gives-you-more-crowds-and-sand/