Creating Stylized Procedural Content

Hugo Beyer did a little overview of the ways he creates great procedural content with Houdini. To learn more check out the full tutorial.

Introduction

Hello guys, the tutorial consists of creating through meshes a stylized floor of grass mixed with dirt and pebbles in Houdini. I want to show you that Houdini has the power of doing that for games, not just ZBrush, Maya, Substance, etc. as Houdini relies on vectors and points. You got to start from there, understand that normal and tangents are important for the productivity. A lot of that is randomized and a lot of it is already in the nodes that Houdini provides, so there’s no need to code, mostly expressions. Houdini has a visual code system called VEX which is more art-friendly and has the same power as a VEX code. For programmers who used to write a line or 2 of code, it will make no sense creating a VOP node. What I really wanted is to show how powerful and robust Houdini can be, how open for creative people it can be.

Proceduralism & Modeling

Maya itself started with the MASH system to create proceduralism, Zbrush also has some procedural noises added. The word procedural is used everywhere. The idea of procedural in Houdini lies is the ability to come back in a non-linear way and change things without affecting your whole workflow.

It’s about getting small elements and bringing it all together without having to paint a whole picture as you have the power to go back in time and apply a different curve or color. That’s what proceduralism is all about. And the idea of creating reusable digital assets makes a huge difference. For an example, if I want to create a curve that has cosine functions I can create controls on that, save it, and reuse it later for any reason. The leaves and pebbles are used quite often in my workflow, so I just go back inside the node and add other inputs and attributes without damaging the whole work.. The points are essential for pivots, with points you can give colors, size, spacing, anything you want to each point and that gets passed to the geo you are scattering. As well as curves.

In Houdini the best approach of doing UV is doing them through curves, even though I didn’t have to create any UVs for this tutorial it’s the best way to do it.

Vertex Color and Composition 

As I mentioned before the points hold these attributes but you can transfer these guys at any point in the flow of your work. Houdini has different types of attributes for points, vertex, primitives and detail, you will see that in the video. Those can be converted at any time and reused. You can composite them and create ramps for curvature, noises, groups of points and much more that gives you control to mix these masks and give you the composition you want. You can also mix in between these attributes on the fly by binding them inside the VOP’s nodes, and composite it from there, or through code. Houdini reads attributes everywhere if you know how to import them or get them. And setting them it’s quite easy. Houdini has global variables that you will need to understand in order to work, like @N, @Cd, @P, etc, which are VEX global variables, those correspond to NORMAL, COLOR of point, and POSITION, but it doesn’t stop there, a lot of the nodes like the sweep node has their own attributes, and it’s easy for you to find out how to use it, select the node, press F1 and Houdini docs explain it to you very well and simple. But again, I go deeper in the tutorial about that.

Scattering

Houdini scattering is very powerful, you can control how you want to scatter by any attribute you want to, I usually find it easier to control by color and normal. I usually create a VOP with a voronoi noise or any other noise and obtain their colors on the mesh I want to scatter, you are also able to have intersection scattering which I explain on the tutorial. There is also a radius of scale, that Houdini calculates for, you called pscale. You are also able to scatter points in the air and raycast them to a mesh if desired, everything is really possible there. It’s very robust. After scattering you are able to pick up random points and assign random expressions to get scale, form, color, etc.

Baking in Marmoset Toolbag

You can actually bake it in Houdini. I didn’t it because it’s not so artistic friendly and it requires more steps than Marmoset. In the video I show how easy is to import the meshes, get the bias distances and bake the masks, and Marmoset is EXTREMELY fast and accurate on baking, that’s why I chose to do it that way. The nicest thing is that they export it to an organized PSD file with all layers you need to import into Substance.

Houdini has a bake to texture function on version 16. The only thing that bothers me is that Houdini uses a specific gamma for each file type, so I wasn’t able to find out why I have to export .png format to do the normal or I don’t get it as sRGB, it’s weird. They still have some steps ahead to make it better, and it’s their first version, so I believe they will be doing something really good there very soon.

Working With Substance Designer

Yes, since I was always a SD fan I like the idea of compositing things there and watch the changes on the mesh right away. I basically used the masks, created roughness and a bit better AO for the stylization. The rest came from the bakes. But Substance Designer is still one of my main tools. I wouldn’t drop Substance because of Houdini, nor vice versa, I think they both can be a great combo if you are willing to learn them.

Things You Can Do

After people watch the tutorial they understand how to create another stylized or realistic texture, rock formations or even tree bark. The tutorial is here so experiment with it. I encourage whoever watches this tutorial, to send me their results. I’d love to check them out.

Honestly, I still have to learn Houdini, recently started doing some compositing nodes with their image editor, and it’s quite interesting to see how it works. I have also been doing some procedural modeling with some scenes, all through nodes and not using any manual modeling (even thou you could).  As I mentioned Houdini is not that artistic friendly, but it’s extremely powerful for those who wants to be creative and technical at the same time.

I recently finished another texture of a thick moss inside Houdini, you can check it out here.

The full tutorial from Hugo Beyer can be purchased at Gumroad. 

Hugo Beyer, 3D Artist

Interview conducted by Kirill Tokarev.