Join Scott Pagano for an in-depth discussion in this video Preparing to export, part of Houdini Engine for CINEMA 4D and Maya.
- Now that we've made our basic Houdini network, we're going to wrap this up as a subnet and promote the parameters we're going to be able to change in our external application and get that ready to export as a Houdini digital asset. So, let's do a few things, first, we'll turn off this normal view. We don't need to see those right now. Make this parameter window a little bit smaller. OK, so let's hit the U key to go back up to the object level. You can see this is just called Sphere because we started with a sphere node and we did all this other stuff inside.
That's fine, we can leave that name for now. What we want to do, we want to select this object and we want to hit this icon right here in the menu bar. You can see that the tools that comes up that says create subnet from selected. So, we hit that and voila, we have this subnet one. You can see in the viewport, everything is exactly the same. So, if I hit subnet one, and hit the I key to go into it, you can see that now, it just basically put that network that we created inside a subnet. If we go inside of that, hitting the I key, there we go, there's what we built.
So,it's basically just like packing into another folder. You can think of all this as just like a file and folder structure. So, hit the U key to go up a level, and the U key to go up a level again. So, let's do what we're going to do. First thing, we're going to change this from subnet one to sphere grid. OK, cool. Now, what we want to do here, is we want to talk about parameters. Because by default, you can see that we have these two tabs, transform and subnet. That of all these different parameters, and quite frankly, we don't need any of them.
All we want to do for this, is we want to have a couple simple parameters that allow us to change this grid, and throw away everything that's irrelevant to us. So, now we're going to talk about the edit parameter interface window. So, I'll right click on my sphere grid I'll choose edit parameter interface. Alright, and now you can see, we have our edit parameter interface window. I'll just size that up a little bit, so we can see what's going on. You can see we have this existing parameters column. This is the main thing we're going to focus on right now.
Let me close up these two little things here and you can see we have root, and then a transform and a subnet folder. This correlates exactly to what we have over here. We have a transform tab, and a subnet tab. If I went into the transform tab, for example you can see that all these options here are represented by all the different options we have in the window. This is how we basically built these windows. Right now, we don't need any of this stuff. We want to throw away all the default stuff. So, I'm going to click on transform, and then over in the parameter description area, I'm going to click on invisible.
Now, I'm going to go back to existing parameters and click on subnet, click on invisible and hit apply. Now, we can see that all of that stuff goes away and we have a clear blank canvas to work with. So now, we want to find the parameters that we want to promote, and promote them to here so we have a nice clean tool that we've built. We're going to move the edit parameter interface window over a little bit. Now, I'm going to dive into this sphere grid by hitting I. Let's find our sphere, click on it, hit I to get inside of there, and now we have our network.
So, there's a bunch of different ways to get parameters into this, you know, parameter list on the left here. We're going to do the easiest, simplest, greatest way to do it. Which is just clicking on a node. For example, let's go to our transform node that changes the scale of the grid, let's go to our uniform scale parameter, let's click on it and we're literally just going to drag it right over here. You can see, now that it's in this list, now, we have a bunch of different options. I'm going to hit the U key twice to go outside. Click on the sphere grid, and you can see, that there isn't anything actually here yet, even though we added it.
That's because after we add parameters, we have to hit apply, and there we go, uniform scale appears right there. This is the name of the parameter that's based on the default Houdini node parameter, but in our world, this isn't just uniform scale, it's actually grid scale now. So, we don't want to change the internal name, but we can change the label so it can be more user friendly and readable by us. I'll change this to grid scale, hit apply again, and excellent, now we have that. Now, we're just going to add one more parameter to this, which was that seed value and the attribute randomize node, just so we can be able to control the randomization, or change it up if we want.
So, we're on sphere grid, hit I to go inside, have sphere, hit I to go inside of sphere. We'll go to our attribute randomize node. We'll get the global seed value, and we'll drag this over here, as well. So, what we're going to do now is change this from global seed to random seed. That just makes a little bit more sense. Hit the U key twice in the network window to get outside of here, and we have our sphere grid subnet. It still just has our one parameter because we haven't hit the apply button yet. So I'll hit apply.
Excellent. We have our random seed value that appears there. Now, I'm going to hit accept, which will close the edit parameter interface window. OK, now we have this nice little tool built that's all packaged up, and we have a few different parameters. So, I'm going to reframe our view, and let's just change these to make sure everything's working. Awesome. We've got our grid scale that is working just fine. We have our random seed that changes the random distribution of those spheres. Excellent. Now, we've taken the Houdini network and we've packaged it up in a subnet.
We've promoted only the parameters that we want to be able to tweak, and we've gotten rid of any parameters that aren't necessary for us anymore. This is really a very simple example, but it'll hence at the incredible power of being able to build really complex and intricate networks, and wrap them up into these nice, clean, easy to use packages that have only the parameters that an artist needs to be able to tweak what they're doing. In the next video, what we're going to do is, we're going to take this, and I'll show you now, how to export this as a Houdini digital asset file, that we can bring into other applications.
This course introduces the typical Houdini pipeline for creating complex systems that can be passed along to shot creation. Scott Pagano shows how to load the Houdini Engine in Maya and CINEMA 4D, create simple geometric networks, build more complex particle systems and fluid simulations, and create a procedural building generator for quickly blocking out buildings in Maya and C4D scenes.
- Overview of Houdini digital assets (HDAs)
- Preparing digital assets in Houdini
- Loading Houdini assets in Maya and CINEMA 4D
- Building a particle systems with the Houdini Engine
- Creating a procedural building generator