Getting Started with Houdini Engine: Creating a simple Asset in Houdini

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In this tutorial, we will learn how to make an extremely simple Houdini Digital Asset and load it inside Cinema 4D.

In this tutorial, we will learn how to make an extremely simple Houdini Digital Asset and load it inside Cinema 4D.

We will learn the most important thing in 3D modelling, how to create a cube, and then add controls to make it fancy.

Cubes are good, but spheres are better, so we will learn how to input any native Cinema 4D object to the Asset.



- After everything has been installed and you're up and running, how do you get HDAs? How do you get digital assets? The easiest way is to go to the Pipeline menu Houdini Engine, and get assets from Orbolt. This will fire up your browser, and it will take you to the Cinema 4D compatible asset page or the Orbolt store. This is a store that is moderated and run by Side Effects, and all the digital assets are here for you to download. Now what we can do is, for example, click on spaceship, and then click on free download and download manually. And after the download has been finished, switch to Cinema 4D. Go to the Pipeline Houdini Engine, load asset. Click on the asset and open it. And here you are. Here is your digital asset. Click on it. Go to the assets tab. Move this up, and you can play around the parameters. Fantastic. That's all fine and dandy. Downloading ready-made Houdini digital assets is very easy, but what's more interesting and more powerful is that you can extend Cinema 4D's capabilities by building your own assets, providing you have some compatible version of Houdini. I will show you how to do that today. Let's switch to Houdini. This is a Houdini interface, and if you want to learn more about it, just refer to the numerous tutorials on the web along the Side Effects website, and it will teach you everything. So let's put our mouse over here and press tab and type 'box'. Press enter, and that will create a cube. And, yes, you've guessed it. I'm going to create a cube asset. Now with the geometry node selected, in order to create a digital asset, what you have to do is the following. Click on this button here. This will encapsulate your box. I double clicked on the box, you can see it here. It encapsulates it in a subnet, as it's called. Now if I want to go up a level, there are a couple of ways to do that. Either click on the OBJ. That will take you up, or when you're here, you press the U key to go up. And let's save these things because it's quite practical. And let's add a name. Let's call this 'cube'. Press enter. So we have a subnet. Inside the subnet we have a single node, which is a box node, a cube. Just press U. And I want to convert this into a Houdini digital asset. I need to right click and say 'create digital asset'. I'm going to be asked for the name. I'm going to leave it at default. Click here to select the save path, add a name, my simple cube 01. Press accept, and then accept one more time, and you will see this huge window here with all these buttons. Don't be afraid. Just press accept. And actually you're done. Let's switch back to Cinema 4D. I'm going to create a new scene. Go to the Pipeline, Houdini Engine load asset, my simple cube HDA, open, and there it is. I have a cube. It has an output. It has no inputs. It's green, which means it works. And if I select the asset and go to the asset tab, you will see it has its parameters, and they're grouped. Look at these groups here. We have the subnet, and we have the transform. And basically this is where all our parameters are going to be. The reason these parameters are here now, it's because these are the default parameters an asset will have. We'll get rid of them later on. So that's how you make a simple cube in Houdini and bring it in Cinema 4D as a digital asset. But that doesn't sound like much fun, does it? Let's go in and add something. Let's go and make the cube extrudable so that all the sides can be extruded. Let's go back to Houdini. So what I'm going to do now is just modify the existing digital asset. I'm going to dive in, as they say, double click. Go to the box, double click in here. And here's my box node. And I'm going to press tab and type extrude, and I'm going to select the polygon extrude, poly extrude. Drop it down and link it. Activate it. And with the poly extrude selected, I'm going to go here and type 1. Press enter. Now you can see that my cube is bigger now. Now why isn't it split? And that's because there's a setting here that says keep point shared on average positions. I'm going to make this no, and there you go. Here we have an extruded cube. And what I'd like to do is expose these parameters here, not all of them. I don't want the transform order. I just want the translate rotate skill inset and the key points shared. How do I do that? Well, let me go up again. So put your mouse over here. Press U to go up and U to go up again. And now because I want to modify, I'm not going to create a digital asset. Actually that menu doesn't exist anymore. What I need to do is go to the type properties. This will open this huge window again. And remember, transform a subnet are the parameters we already have, but we don't need. So I'm going to select the transform, make it invisible. Select the subnet, and make it invisible. So now there are no parameters. Now what happens is if I press accept or apply, I'm going to press apply. This has applied the changes I did and has saved the digital asset again. Let me say accept for now, and let's go back to Cinema 4D and see what happened. I'm going to delete this asset and go here, load asset and select again. And now you can see we have the extruded version. If I select it here, now it has no parameters whatsoever because we deleted them, but I want controls. I want to be able to move these dynamically. So let's go and add those parameters to the interface. Switch back to Houdini. So again, right click on the subnet. Type properties. And how do we add them? Now you can see this big window. We're on the second tab. Sometimes you will see it on the first type. Just ignore it and click on parameters. Here's where we construct or modify our interface. And how do we do that? Well, there are a couple of ways. First of all, we can go by double clicking to the appropriate node. I'm going to click on this, and you can drag the parameter. So I'm going to drag and translate over here, and press accept. Now I'm going to go back to Cinema 4D and see what happened. Delete this. Pipeline, load asset, my simple cube. And if I select the asset now, you will see that we have one parameter. And when we move it, the cube changes because the extrusion changes. Fantastic. But I want to add more parameters. Well, let's go and do that as well. Let's switch back to Houdini one more time. Let's do the same exercise again. U, U, to go up and up. Right click, type properties, and I'm going to delete this, so I'm going to select it and press backspace. And now I want to add everything inside this little tab. Now look at this. We have these green color. That means that these are connected to some kind of expression. That was because I used the translate as a parameter. Okay? Now if I apply, you will see that will go black again. You have to apply for any changes to be accepted. So how do I add everything? Let me see if I drag this here what will happen? Actually, nothing. We cannot drag the tabs. But I don't want to drag them one by one because I'm lazy as everyone that knows me knows very well. So how do I do that? You go to the left panel. Here is a repository of possible interface elements, and it's very similar to the user data interface construction we do in Cinema 4D. If you go to the from nodes, that is going to show us the hierarchy of our whole scene. So this is a vertical representation of this. I'm going to twirl my cube open, twirl my box open. Go to the polyextrude, twirl this open, and I will find the local folder. Drag it from here into here, and I have everything I can see over here. And I'm going to delete the transform order, click on it, and press backspace, click on rotation order, and delete it. And I don't want local symmetry. I'm going to delete this as well. Click backspace, and it's deleted. And now I'm going to apply this and accept. You see that they all go green because now they're connected to some kind of expression, which is the interface. And let's go back to Cinema 4D and see what happened. Let's delete the previous asset. Let's go to Pipeline load asset and load it one more time. Select it, and now you can see the parameters have everything we want. You can see that the parameters group and underneath, the local group. These little groups, which you can twirl open and closed, are represented by a folder when you're constructing the interface. We'll see this later on. Anyway, now we can control all these parameters and make an interesting cube, and we can scale it and do all sorts of things. And select average positions or no and so forth. Excellent. Now let's take this one step further. This creates a cube, a standard cube. By the way, if I select all these parameters by clicking and then shift-clicking and right click and say reset to default, it's going to reset to the default state. And you select this and command to deselect it. So what I want to do now is I want this asset not to work with the standard cube. I want it to work with any object I input, so I'm going to create an input parameter. I'm going to drop any object from Cinema 4D in that input parameter, and the asset is going to extrude all the polygons of that object. Let's see how we can do this. Let's switch back to Houdini. So back in Houdini, we have a hard coded, so to speak, box here. I want to replace this with something which we can use as an input. Let's say a wild card. So what I'm going to do is select this and delete it. Before I delete it, just to remind you, press U and U. This is our asset. Double click to go in, double click to go in. That's how we got here. Select this, delete it. There's a node in Houdini that's called, press tab, it's called Merge. And the one you're looking for is actually the object merge. I'm going to click on it. Go here. And what I'm going to do now is this object merge allows me to put any object as an input. I'm going to connect it to the poly extrude. Currently, we don't get an output because we don't have anything in here. It's just empty. But don't worry because the functionality is already there, it will work. So I'm going to go up and up and right click again and type properties. And I'm going to dive in here once and then twice, select the object merge, and drag the object in here. So what I can do now is with this parameter selected, I can actually change the label and I'm going to call it 'drag an object in here'. Okay? Just to make sure that they understand what we're talking about, press enter, and then accept. And let's go back to Cinema 4D and see what happened. Just like previously, let's delete this asset. Pipeline Houdini load asset. Let's load the same asset again, and you can see now it's red. And it's red because it requires an input, which is called 'drag an object in here'. Okay? Oh yeah. Okay, I'll make a cube. Select my asset, drag my cube in here. Make sure that this cube is invisible, and you can see that we have a cube. The reason why it has this odd shading is that we haven't done anything to help with normal recalculation, but don't worry about this, we'll fix it later. So we have the cube, which is being inputted in the asset, and then it gets extruded. Let me delete the cube. Let me add a sphere. Select the asset, drag the sphere. And now you can see that this sphere is being extruded. So what we've done in these very brief minutes, we've created an extrude asset. And the good thing with this is that it's non-destructive. I can change my sphere and it will adapt accordingly. So there you go. You've created your first useful tool in Houdini and brought it inside Cinema 4D as a digital asset. And let's move on with more interesting stuff now.
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