I know most of you aren’t interested in this, but hey, there has to be at least one other dickhead out there that wants to compile the USD Plugins for Windows.
We need to install a couple things, namely Microsoft Visual Studio 2017 Community, and also CMake. Get them below. When installing Visual Studio grab all the C++ add ons.

Microsoft Visual Studio


Okay, so lets get to it. We need to grab the houdini toolkit folder, located in;
“C:\Program Files\Side Effects Software\Houdini 17.0.459\toolkit” for example. Copy and paste the toolkit (and obviously all it’s contents) to somewhere. I have whacked mine in here: W:\dev\toolkit but put it wherever you want. We need to set a couple environment variables in order for everything to work.


Let’s make a new environment variable and append the path variable. Remember this is the “User variables for YourName” section, not the System Variables. Make your new var CMAKE_PREFIX_PATH and fill in the path the cmake directory.


And now, let’s append the user path variable. Edit this bad boy, and hit new to append our path to the bin folder.


Sweet azz. Now let’s keep moving, it’s already making me sleepy. In the root of the usd_houdini_plugins folder, which for me is: W:\dev\toolkit\usd_houdini_plugins\
make a folder called “build.” Now In here is a “CMakeLists.txt” file. The default output is to dump everything into C:\Users\YourName\Documents\houdini17.0\ and this is shit. It will be dumped in with everything else, and be hard to fish out. If you don’t care about this, ignore the below custom output location set up. But for those who want to keep it out of there, see below!

Here’s the Vanilla, let’s delete stuff. Remove all the if >>> down to endif, and set your path to where you want to output the data.


Below is what I’ve cleaned it up to. It’s where all my houdini/pipeline tools live.


And here is the append line to make the DSO go to your custom locale. Just add the INSTDIR pathto\\where you added in above\\dso in the line below, and you’re gold.


Here is my CMakeLists.txt
Okey dokey, with that done, open a command prompt and CD to the build folder we made earlier. Now your prompt is at W:\dev\toolkit\usd_houdini_plugins\build> (obviously your location is different!) let’s do some hacking.

run: cmake -G “Visual Studio 15 2017 Win64” ../  and wait for the magic. Here’s a boring gif of the process for sheer entertainment.


Amazing. I feel like Neo, I’m sure a pill offering is on the near horizon for me. Hop inside the build folder and you can see all our hard work. Double click the following: “usd_houdini_plugins.sln” this will launch Visual Studio, all ready to rock n roll.

All we need to do is select the “install” and go and change from “debug” to “release” then right click “install” and “build”


Once it’s all done, you’ll get some sexy confirmation messages in the output window. If it all went to plan, there will be all the USD Plugins in the location you chose earlier.


Sweeeeeeeeeeeeeeeeeet! Now add this to your houdini.env file:                          HOUDINI_PATH = “W:/Pipeline/Houdini_USD;&”

We made it Wendell! I hope you managed to stay awake for this. I didn’t. Here’s a zipped up binary built against 17.0.459 for you lazy bastards Houdini USD Plugins








Pixar USD on Windows 10

January 4, 2019

Well after a mind-numbing experience building USD on Windows, a feat I won’t be repeating in a hurry, due to how shit it is, I present a much easier route, which results in minimal hair loss. Victor Yudin has been busy compiling and releasing USD + goodies under his saturn github.

It comes with UsdView, Embree plugin, Maya 2018 plug, MaterialX, and OSL support. Hurray! Thank Jesus. What we will do is get his compiled version up and running, bind the cmd file to the .usd extension so we can just double-click, and even add a USD icon!
It will be, almost useful.

Grab this version: https://github.com/VictorYudin/saturn/releases/download/1.0.160/usd-v18.11.tar.xz

As the latest Houdini 17 USD plugins(which we will compile in the next exciting episode)
are built against v18.11, not the more recent v19.01, simple huh?


So once we unzip it’s almost ready to go, except that the “usdview.cmd” script inside the bin folder only contains the following:

@python “%~dp0usdview” %*

We need to add some more info in here to help point everything to the correct versions/locations of all the shit it needs. So delete that lonely line, and fill  the script with the following.

@set BINP=%~dp0
@set LIBP=%~dp0..\lib
@set PYP=%~dp0..\lib\python
@start pythonw “%~dp0usdview” %*

This is so simple, it feels like installing a Windows 98 screen saver. Let’s continue! Next on the list is testing out our setup to see if UsdView launches. Now is a good time to grab some USD data, head on over to: http://graphics.pixar.com/usd/downloads.html and grab the kitchen set. Once you’ve unpacked, we need to open a terminal, and cd to the bin folder. the command for launching is simply: usdview “path/to/usd” see below.


Like the Angel in it’s a Wonderful Life, you just have to believe you are making a difference, and to hang on. Let’s see what happens….


Huzzah! We made it Wendell. By default the viewport is the hydra openGL, but Victor compiled Embree too, so if we go to View>Hydra Renderer> Embree we will toggle over to ray traced land. It’s a fair bit slower, so be mindful of zooming around. There is preliminary AOV support in this mode.


And prim ID and Normal AOVs.



Sweet. Now this is all good and well, and we could/should create a shell working environment that has usdview in the path, etc, etc, but let’s go all out lazy Windows double-click shall we?

The file extension .usd isn’t registered in Windows, so we need to do this manually. Fire up a terminal in “admin-super-overlord-mode”

type the following: ftype extfile=”W:\Pipeline\usd\bin\usdview.cmd” “%1”

obviously replace the path with your location.

Next type the following: assoc .usd=extfile

Now if you double-click the Kitchen_set.usd file it should launch usdview. For our final trick, we need to use a nice free utility, that doesn’t even install!

file types manager

Grab the x64 version here: http://www.nirsoft.net/utils/filetypesman-x64.zip and unzip that bad boy. Launch the application directly, and scroll on down to .usd file type.


Right click the usd extension and select “edit selected file type.” navigate to the location of the .ico file, and maybe even pop a brief description in. Here’s a link to a little USD ico file I made: usd_simple64.ico


In the next exciting installment we compile the Houdini 17 USD plugins from scratch, and demo exporting out.








I’ve been having a serious look at using spheres and also boxes to represent the collision
shape in bullet simulations. Spheres are great in that you can rely on the geometry to not get caught and hang on to each other. Boxes offer a nicer settling motion in certain setups too. The main reason I wanted to look at it, was to avoid always needing to use glue constraints. Sometimes I want a nice quick voronoi fracture that uses the clustering option, and this yields shitty collision approximations with convex hulls.

Enter vdb sphere packing! It allows me to fill the wacky geometry shapes and use those as colliders. I just save out my points, and transform the original pieces. Voila!


Dot Product & Normalize

September 25, 2018

These are two of the most used functions in Computer Graphics, and quite a lot of the time, the underlying process of how it works, is ignored.

Normalizing a vector is essential for a variety of reasons, and below is the long way around to do it, as opposed to the normalize VOP.


We need to find the length of the Vector, as this will be used as the divisor for the x,y,z components of the Vector to be normalized. This is done by taking the x,y,z components and taking each to ^2 power. Then we add those values together and find the square root. Now we have the length of the Vector, and  can use it as the divisor. Voila!

Now it’s time to do the Dot Product! Mysterious I know. But very handy in shading/lighting and other areas of Computer Graphics. The Dot Product is the Cosine of two normalized vectors. Cosine being the trig function equal to the ratio of the side adjacent to an acute angle (in a right-angled triangle) to the hypotenuse. That’s pretty neat!

Below is a quick animation of the Cosine around a unit circle. The unit circle being a radius of 1 of course. The Dot product of two normalized vectors, which we will see is just multiplying their components and adding them together, creates a trigonometric function.

Here is the long way of doing it, instead of using the dot product VOP.


First we normalize both Vectors. Then we split the x,y,z components of each vector and multiply them. Adding the results of this all together. Bingo! Very Simple really isn’t it. Additionally, using a trig VOP to use arc cosine along with a radians to degrees, will give you the actual angle between those two vectors.

I Have been working on this for the last six months.

Tinkering with using uniform or varying volume, along with reflection and refraction to create more interesting attenuation of light.


So a major pain in the arse in VFX land is trying to get a particle sim, well any sim that is stored as points, out of Houdini into Maya for rendering. Yes yes we’d all like to just use Mantra, but a big part of VFX lighting is done in Maya.

Autodesk’s Alembic tools in Maya are shit. End of discussion. Nothing like the delayed load, deferred to the GPU, streamed off disk benefits we enjoy in Houdini. The J CUBE guys in Japan have been making a product to solve this cross-walk. Multi-Verse is it. And by it, I mean IT. Does exactly what it says on the tin. Lightning fast loading of Alembic or USD into Maya. A typical 10 million vert model will load in under 1 second, there in your viewport, to tumble around with no lag. You have a choice of geo, points, bounding box, or hidden for display, and the ability to actually scrub your viewport with amazing feedback. It deals with packed geo from Houdini automatically, so your Alembics out of Houdini, if for example, are instancing a few bits of unique geo to a bazillion points, then your packing before instancing will be respected. That means tiny Alembic files due to the multi-verse procedural being able to feed to Arnold, prman, 3Delight in a manner you’re used to in Mantra. Full support for Mantra style point velocity blur as well.

What I have never been happy with, is how hard it is to simply save points, with attributes, and have them render with a lightweight primitive, that can utilize those stored attributes in Maya. What follows is a nice little walk through of the process for getting a particle sim out of H into Maya, and rendering with 3Delight.

Let’s make a simple popsim, and set a couple attrs for pscale and color!


Alembic ROP settings!

So we are using Houdini 16.5.323, as from 16.5 onwards per frame Alembic caching is sweet! Much better than a huge single Alembic. Untick render full range to output a per frame, and enable full bounding box tree, as this makes life easier in Maya. Do not enable motion blur, it’s not needed. We have point velocity in this example, but even with fixed point counts, for regular motion blur, multi-verse will correctly interpolate, even with just one sample(the cached alembic frame).


Our lovely Mantra render!


Loading the Alembic with multi-verse

Use the green loader button, and since we are loading per frame, tick the option and remove your existing frame number, and replace with #. So, dude_1234.abc = dude_#.abc

You have options for full geo, points, bbox, and hidden, on the same shelf.


3Delight assignment panel

If you’ve ever used 3dl in the past, you know this panel well. In the new version of 3dl this will no longer be around, but for the next couple months we have to live with it. Select your alembic that we just brought in, and launch the panel, from the shelf. On the Attribs section, hit the little triangle and it will add a “delightGeoAttribs” panel to your Alembic. This is for doing all many of per object overrides, so much so, that it was one of the major selling points of 3dl.


Delight attribs, and Attribute re-mapping!

on the left is the panel that opens when you hit “Add / Remove Attributes” on your delightGeoAttribs panel that we attached earlier. We only care about the Particles options, so tick All Particle Attributes and close. What you will also see, is there is a Multiverse tab on our delightGeoAttribs. Open the Geometry Mappings and re-map our pscale and color to: pscale=width; Cd=Cs to make everyone happy! Width is the ri spec for radius, and Cs is color. Now when 3Delight renders it will pick up the width correctly and the stored per point color will come through in the diffuse of the 3dl shader. Point velocity motion blur scale can also be adjusted here, to accommodate different scene scales.


Delight particle settings

When we added the Particle Attributes, it gives you the following. Here we make sure that our points are rendering as Spheres, in Object Space, and I have reduced the particle scale globally to closer match Houdini. I’m sure it should be an even number, but meh. Interesting point to note, you can set your points to be in Raster Space, and they will always render the same size, in pixels, no matter their depth. So you can easily mimic the behavior of Krakatoa!


3Delight render pass

3dl has always had a nice pass manager, and all you need to do is to create a pass from the 3Delight menu. Once you do, set your camera and environment light in Scene Elements. The default render engine is the path tracer, so just enable Indirect Illumination and motion blur, and off you go!

It should be noted that the completely re-written 3Delight V13, which is coming soon, has a much more streamlined interface, and you will literally be only changing a couple settings. OSL based, designed for Interactive rendering, it is unbelievably quick, and if you have still got a hangover from the previous version, with it’s plethora of overrides and fiddly TD options, then you will be very pleasantly surprised.


Render time!

So our Alembic points from Houdini render perfectly. Motion blur, color per point and radius per point too. With the new version of 3dl being much quicker, which the current version rendered these in 60% less time than Mantra, coupled with the multi-verse tools doing the cross-walk, it’s an exciting time indeed.