# Working with particle forces

## Video: Working with particle forces

The Emitter Objects spits out particles into the scene, but they pretty much just go in a straight line or whatever direction they were going in when they came out of the Emitter. Particle Forces allow you to modify the particles after they come out of the Emitter. Let's create a Particle Emitter. Let's go to the Simulate Menu and under the Particles, let's tear off this Menu. I'll Highlight those double lines and then remove that and let's just park that right over here. Now what I want to do is to add an Emitter to the scene and let's spit out a lot of particles.

## Working with particle forces

The Emitter Objects spits out particles into the scene, but they pretty much just go in a straight line or whatever direction they were going in when they came out of the Emitter. Particle Forces allow you to modify the particles after they come out of the Emitter. Let's create a Particle Emitter. Let's go to the Simulate Menu and under the Particles, let's tear off this Menu. I'll Highlight those double lines and then remove that and let's just park that right over here. Now what I want to do is to add an Emitter to the scene and let's spit out a lot of particles.

I'll hit Play on the keyboard. You can see we've just got a few particles here. Let's go into the Particle Menu and change that to, say, 500 x 500. Now we've got a lot of particles coming out. We're not going to be using an object under here for now, we just want to see what the particles themselves are doing. And this will give us a good visual indicator. These objects underneath the Emitter are the Particle Forces, and the Particle Forces can be used to modify. They're Operator Objects, and they modify the Emitter Object. Let's start off with the easiest to understand, which is the Gravity. I'm not going to cover all of these objects in this movie.

But they all work in essentially the same kind of way. So I'm going to cover the ones that I think are the most important. The most important one in my opinion is the Gravity Object, and let's add that to the scene. And when I add that to the scene, let's rewind and hit Play. You'll see that our particles immediately are forced downward. The gravity has an acceleration, and that controls how fast particles are pointing downward. Let's stop Playback, Rewind back to 0. And let's go to the Acceleration and change that to a higher value. If I make it a higher value, say 500, you can see that our particles now are drawn down faster.

If I rewind that and change it to a lower value, say 50, you'll see that our particles will draw down slower. By default, the particles have zero gravity. So if I wanted to I could turn the Gravity Force Object off by clicking its green checkbox, and then I'll rewind back to 0 and hit Play again, and you can see that my particles are unaffected. Let's rewind back to 0, turn on Gravity. Now let's talk next about the Deflector Object. I'm going to add the Deflector Force Object to the scene, and the Deflector Force Object comes in as a rectangle.

And it's in the same location as the Emitter Object. Let's drag that out here, and watch what happens when I hit Play. Our particles come out and then the ones that strike the Emitter are bounced off in a new direction. Let's rewind back to 0. Let's make the Deflector Object a little bit larger. Let's make it, say, 500 x 500. That way there's no chance that our particles will miss. And let's angle them upward. And I'm going to rotate this, that's the wrong direction. Now let's rotate it back up this way, and I'm going to slide this down into the particle stream.

Now the Deflector has a Bounce option, that controls how much of the energy is returned. By default it's 100%. You can see that the particles bounce off the Emitter with the same speed that they approach the Emitter. If I change that Bounce down, let's call it, say, 75%. Let's rewind back to 0 and hit Play again. You can see that now they'll bounce off slower. So let's leave it like that and crank up the Gravity back to, say, 250, which was the default.

And now, we're going to get a nice little stream of particles. The interesting thing about the Deflector Object is that we can duplicate it. We'll hold down the Control key and make a copy, and let's rotate it into position, and drag down the Z-axis. And now you can see we have multiple Deflectors. There really is no limit to how many of these you can have in the scene. You can do a lot of redirection with your particles. I can rotate this around this way. Let's slide that forward just a bit.

And then let's increase the amount of time that our particles have to live. Right now, it's looping back at 90 frames. Let's change the frame range from 90 to 300, and then adjust our Preview Slider here. And then rewind back to 0 and hit Play. So you can see that it's splitting when some of the particles strike the Deflector and others pass on. So the Deflector Object can be really useful. The next most important one is something called Wind.

And let's turn these Deflectors off by killing their checkboxes, and let's rewind back to 0. And when I hit Play, you'll see my particles are just being affected by Gravity. Let's disable the Gravity too for just a moment, so that we're only seeing the particles. Now let's add in a Wind force. When we add that, we get this cool looking little fan. The way the Wind Object works is that it directs the particles along its Z-axis. So if I hit Play right now, you'll see that the Wind Object is spraying the particles, making them speed up, because they're traveling parallel to the Z-axis of the Wind Object.

Let's hide the Deflectors as well. When I disable them, I can still see them on the scene, it's a little bit confusing. So let's hold down the Option or Alt key and then click twice and drag down to paint those guys invisible. Now let's take the Wind Object. Hit R on the keyboard to bring up the Rotation Tool and rotate the Wind Object so it's pointing up in the air. And let's drag it down like this and put it out here in this area. And then we'll rewind back to 0 and hit Play. You can see that the Wind Object is blowing those particles up.

On the Wind is a really important option called Falloff. Under the Object Properties, you can adjust the Speed and Turbulence and that sort of thing. But the Falloff controls where the particles will be emitting. Let's hit Stop and then go into the Shape pull-down and change it from Infinite to be a Box. When I do that, I get this box around my Wind Object. Let's make the box quite a bit larger. And then let's move the box up into the particle stream.

So the particle stream is going to pass right through there, and watch what happens. Actually, let's take the Wind Object and move it out just a little bit more. Let's rewind back to 0 and hit Play again. You'll see that as they hit that red field, they'll start to upward. And just like the Deflector Object, you can have multiple Wind Objects in the scenes. Let's take this first Wind Object. Hold on the Control key and drag a copy. And then let's take that one and rotate it a different direction.

I missed the axis band that time, let's grab the axis band and rotate it around its X-axis. And let's move it up on Y. And then, it's important that the particles pass through this red box, otherwise they won't be deflected by the wind. And let's rotate that down a little bit. So now what we're going to get is a stream that's going to pass up this way, pass in this way, and then head back down again. Let's rewind and hit Play. So you can do a really nice job of directing that wind. Underneath the Wind Objects, I'll go to the first Wind Object, and there is under the Object Properties, a Speed that controls how fast the wind is blowing.

And then Turbulence, that controls how smooth the wind is. Let's introduce a lot of Turbulence and let's rewind back to 0 and hit Play. So in first one, you'll see that the Wind is going to spread them out, so it's not blowing evenly in one direction. You can see that the particles are being so displaced by the Turbulence that they never even make it to the other Wind Object. Let's hide these two Wind Objects again and talk about one more object, and that is the Rotation.

Rotation allows you to introduce rotation into the particles. And this is different than the Rotation Option on the Emitter. This is going to rotate the entire field of particles. Let's add a Rotation Object to the scene. And when we rewind back to 0 and hit Play, you're going to see that our particles are now creating a vortex, and if we look down the tunnel of this vortex, we can see that it is really hypnotic. Let's back out a little bit and take a look at that.

So the rotation is causing them to spread outward on their axis. Because what happens is the particles are coming out in a straight line, but then they're being spun, and they continue off in the direction that they're being spun in. And if I change the Angle Speed, that will increase the speed of the Rotation, let's make that like 60. Rewind back to 0 and hit Play. And you'll see that they'll spin off even harder. Let's hit Stop. Now if we take the Emitter Object and go under the Emitter Options and change the size of the Emitter, and let's make this, say, 10 x 10, very small Emitter.

And then, let's rotate it upwards. Let's twirl that up on its axis. Remember the Emitter emits along its Z- axis. And then let's hit Play one more time. You'll see that these guys are going to spray out in a spiral, and that's because of the way that the Rotation Object behaves. The Rotation Object rotates around its Z-axis. So the particles are being created in spiral around that axis, and you can have a lot of fun with that. Let's take the Rotation Object and rotate it up as well. Let's rotate that up so the Z-axis is lined up with the Emitter.

Let's rewind back to 0 and hit Play one more time, you'll see we'll create a cool looking tornado. So those are what I think are the most important of the Forces. They all work essentially the same way. They have some options that you can change that affect how they affect the particles, and most of them have a Falloff option that allows you to limit how much of the particles or how much of the scene they're actually affecting. In the next movie we'll see a practical example of how to use the Particle Emitter to create an effect.

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#### This video is part of

CINEMA 4D Essentials 9: Particles and Dynamics

14 video lessons · 4681 viewers

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1. ### Introduction

58s
1. Welcome
39s
2. Using the exercise files
19s
2. ### 1. The Basic Particle Engine

28m 38s
1. Understanding the Emitter object
8m 17s
2. Working with particle forces
9m 48s
3. Particle exercise: Creating an impact splash
10m 33s
3. ### 2. Thinking Particles

27m 54s
1. Explaining the Thinking Particles (TP) workflow
6m 43s
2. Breaking down the TP standard emitter
12m 18s
3. Using TP with the MoGraph Tracer
8m 53s
4. ### 3. Dynamics

30m 6s
1. Understanding the dynamics engine
7m 32s
2. Explaining the difference between Rigid and Soft Bodies
5m 1s
3. Working with MoGraph and dynamics
5m 50s
4. Combining TP and dynamics
4m 32s
5. Creating dangling objects with spline dynamics
7m 11s
5. ### Conclusion

17s
1. Final thoughts
17s

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