MOPs @ Houdini Hive Worldwide

In case you haven’t seen it already, my presentation on MOPs at Houdini Hive Worldwide has been online for about a month now. Here’s the presentation: I’d forgotten to upload the example files I built during the presentation. They’ll be included in the examples directory in the next Experimental release Read more…


Doing away with Houdini.env

This is a sort of sequel to the previous post I made about handling the Houdini.env file, and about configuring environments in general. Houdini 17.5 introduced the concept of “packages”, which are little JSON files (JSON meaning JavaScript Object Notation, filling a similar role as XML or YAML) that define Read more…


Dealing with houdini.env

I continually run into confusion from Houdini users about how the Houdini.env is supposed to work, what the syntax is supposed to be, or even what it does in the first place. It’s easy if you’ve been trapped in pipeline land (like me) to think that environment configuration is even Read more…


Raytracing AOVs in Mantra

I meant to write a post about this a long while ago, but couldn’t be arsed to do it, apparently. Sorry! Something that artists take for granted in render engines like VRay and Arnold is the ability to reflect and refract AOVs / render elements / render passes, depending on Read more…


VEXpressions in your HDAs, using Python!

Update: Imre Tuske from Weta pointed out that there’s a simpler method… it turns out that you can force expressions to evaluate inside a Wrangle by wrapping them up in backticks. So if you have a channel called “do_vexpressions” to enable or disable VEXpressions, and another channel called “vexpression” that Read more…


The rainy forest cinemagraph, Part 2

Continued from the previous post.

Part 2 here is all about the hero plant, which was by far the most time-consuming part of this whole process. The animation ended up being done primarily using FEM, which in retrospect was probably overkill. If I were to try this again, I’d probably try to build a more procedural system involving IK chains with maybe a layer of simple soft body dynamics on top to add springiness. Going the FEM route meant that each iteration took about 30 minutes to simulate, which adds up pretty fast. There are some neat little shortcuts elsewhere in the process, though, that hopefully some readers will find useful.

The hero plant

I am a masochist so I again started with L-systems to create the basic plant structure. L-systems are one of those things that start very simple and quickly build in complexity until they’re totally unreadable, so you generally want to keep notes of what the rules are actually doing as you build them. Of course, the notes from the original .HIP file that I posted are outdated, as they apply to an older version of the plant, so if you’ve already checked out the .HIP you may want to read these more accurate notes.

Here’s what the rules look like:



The rainy forest cinemagraph, Part 1

Last week, I finally finished a project I’ve been poking at for an hour or two here and there over the last year. It was a sort of modest attempt at making something for myself instead of for a client, which I rarely had the time or inclination to do while working as a production artist, and an excuse to learn Redshift3D, which is a fantastic GPU renderer. I’m pretty obsessed with rain, growth processes, and the north coast of California in general, so doing a forest scene seemed like it would cover all the necessary bases. I also wanted to try to make the scene as procedurally-driven as possible, and I suppose it’s *mostly* procedural, aside from a few textures and the hero plant simulation. Here’s the final product:

rainy forest cinemagraph from Toadstorm Inc on Vimeo.

The next few posts on the nerdblog here will be describing some of the processes used in creating this scene. I tried to keep things as organized and as procedural as possible, though of course in practice there are always going to be loose ends and corners cut. Some caveats before I start:

  • The scene scale is totally screwed up. Yes, I know, noob mistake.
  • There are a lot of caches. These sort of grew organically so that I could iterate on things faster. The /out/ context has a dependency chain that probably will cook all these dependencies, but I’m not guaranteeing it will work perfectly as-is. Sorry.
  • It was dumb to use RS Sprite on extruded geometry. I mostly got away with it, but it doesn’t hold up well up-close around the edges.
  • I may have forgotten a dependency in the .ZIP file I uploaded. It’s certainly possible and honestly likely that something is missing, and in this case please let me know so that I can include it.

Okay. With that out of the way, here’s the HIP file and some textures: rain_leaves.zip

Now, onto Part 1: The Stump and Moss.