Name: Houdini Isn't Scary: Part 3 - Dynamics
Uploaded: 2025-04-02T09:21:04.000Z
Duration: 21 min 35 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Welcome back to Houdini isn't scary, part 3, dynamics.

Adverbs of degree

So in this part we're doing something completely new, we're going into dynamics.

Basic passive voice

Now dynamics are used to create simulations, and simulations are approximations of real life systems.

What that means is we can create things like water, and fire, and smoke, and snow, you know, destructive forces, and all of these different things that are organic and you cannot keyframe and animate, but are rather generated through dynamics.

And as you can guess from the word dynamic, it's the opposite of static, so it's things that evolve over time.

So let's not waste any more time, let's get straight into it.

From where we left off last, we have our donut with its icing and its sprinkles.

And if you didn't save this file, don't worry, there is a link down below to download the one that I've created for you.

Everything is named, I've also added some nodes, you can go read those, all of these have been renamed so you know exactly what they do.

But if you have your own file, you can also continue with that, and that's perfectly fine.

So what we're going to be doing now is creating dynamics.

So to start on our first dynamics network, we can go ahead and drop down a geometry node.

We can rename this one to a dynamic sprinkles, just by double-clicking on the name.

And then we can dive inside by double-clicking on the node.

So once we're inside, as expected, we can see our ghosted donut.

And if you can't, remember to just switch on ghost other objects in the top right.

In here, we're going to drop down a grid.

And we can drop down a grid in our dynamic sprinkles node.

And remember from part one, you can just move around by holding space.

So we're going to scale this down to a two by two grid so we can see it there.

And then we're going to drop a transform node because we want to move this up.

And what this grid is going to do is it's going to emit points.

We're going to have points that fall from this grid and they land on our donut.

We're then going to copy tubes to those points to make sprinkles.

So we're dynamically creating some sprinkles that are going to be thrown over the donut.

Now, the next thing that we want to do is we want to animate this grid.

Because as time passes, we wanted to move from the left-hand side of the donut to the right-hand side of the donut.

So to do that, what we're going to do is firstly move our grid over to the left.

Then what we're going to do is we are going to hold alt and click on this word that says translate.

What that'll do is it'll make all of these green.

And what that means is that we have a keyframe on the current frame.

Now, if we go and move along our timeline, we can go to the bottom and just click on this one where it looks like a flag and drag it across.

We can drag it all the way over to about 230.

And then what we're going to do is move back up to our grid and move it over to three.

And now you'll notice that it's no longer green.

Yellow means that something has changed but has not been keyframed.

So what we need to do is hold alt again and then click on translate.

So now if we go back to the beginning, you'll notice that as we play this back, our grid will move from the left to the right.

And if yours is playing back too fast, then you'll just need to check the real-time toggle.

So click on real-time toggle to activate it.

Because if it's deactivated, Houdini will just play this back as quickly as it can.

When this is activated, it'll play it back at 24 frames per second.

But now we need to turn this into an emitter.

So what we need to do is we need to create particles.

And you create particles inside of a dynamics network.

Now particles are also referred to as POPs.

And POPs just stands for particle operators.

And you may have heard of other terms like this.

Basically, SOPs is everything that we've been doing.

DOPs is what we're going to be doing in this tutorial.

So POPs fall under dynamic operators because particles are dynamic.

So to create our first dynamic network, we're going to press tab and just type POP.

And you'll see over there it says POP network.

We're going to take our transform and plug it into our POP network.

Set your display flag on the POP network.

And as you can see there, it says DOP network.

That just means dynamic operator network.

So let's dive inside of this and see what's going on.

So here's an illustration that basically breaks it down for you.

At its core, a dynamics network needs a solver.

What the solver does is it takes all of the information.

It takes your parameters, your settings, all of your inputs, and mixes them all together in a part and outputs something for you.

So this is basically the brains of the dynamics network.

Next, on the left, we have something that is absolutely always necessary.

So the object goes into the leftmost input of the solver.

And if you remember from our previous tutorial, we said that generally what goes into the left input of a node is also what is output by that node.

And that's the case with dynamics as well.

And then it gets adjusted by our POP solver.

Now on the right hand side, we have sources.

So what happens here is we source things into our dynamics network.

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Houdini Isn't Scary: Part 3 - Dynamics

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