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In this movie we're going talk about smoke, a very simple smoke. I just want to talk about some basic parameters that you can adjust on particles so that you can customize what your smoke looks like for your particular scene. So I am just going to do some very simple easy parameters to adjust. I have little weird particles emitting here, not too impressive. Here they are coming up out of that. They are emitting out of this SmokeEmitter and you can see that I have the Visibility of the plane that they emitting from off. Turn that on and you can see they are emitting from a very simple little plane right there.
Turn the Visibility back off and we'll talk about the parameters that I already have adjusted on these little particles. Well, on the particles shapes themselves, I have right now an Opacity ramp. Let's look at that ramp. And so at the start of the particles life right now, they are not quite opaque; they are 0.7. And somewhere before the particle's life ends, well almost the eight of the way before it ends, the particles go completely transparent, which is what smoke particles might do.
They might start at opaque. Well they actually might start out a little bit transparent then get opaque and then by the time, the smoke particle gets to a certain distance, it turns transparent. So over the smoke particle's life I am going to have it go from opaque to transparent. The next thing I am going to look at is the Window, the Rendering Editor, the Hypershade. Now of course in the Hypershade I have this particleCloud attached to these particles, right there. So let's go look and see what I have in this particleCloud right now. The Color and the Life Color I have attached to a ramp2.
Now ramp2 is going to show what color their particles are going to be from the start of its life to the end of its life. If I go into that, I can see I have the particle changing color during its lifetime. At the start of its life this is the color it is,and then kind of third of the way up it gets a bit brighter. And then by the end of its life, kind of an eighth of the way before its life is over, I have the particle maybe turning black, value zero. The other things that I have that I might have adjusted is the Density.
The Density has to deal with the Transparency of the particle as well. So I have the kind of Density of .2 and then I also have a Blob Map on it. And the Blob Map is a scaling factor that's applied to the Transparency of the particleCloud and it gives it a nice texture and you can see that I have put a cloud1 Texture and I have put the Contrast pretty low on that. Roundness, this can help your particles not be as round, from zero to one for complete roundness. Let's go back into the particles and look what we have got here.
I have got my Life Span for particle under my Current Render Types here, I have the Radius. I have the Threshold. The Threshold is how smoothly the cloud particles have blended together. Right now I have zero; they are not smoothly blending together at all. I could go all the way up to 1. We can try playing with that. Just see how smoothly the cloud particles themselves blend together. The Surface Shading can tell you how sharply the clouds are displayed. The value of 1 displays the clouds more distinctly. A value of zero creates a cloudier effect. So all these things can be adjusted too.
Now let's go and try to put a few expressions on them. Now when I am making a cloud say with smoke, I might want these smoke particles to grow in size during its lifetime, kind of like more billowing out. Add some expressions. So let's start my smoke particle out. My radius of my smoke particle, to start out, equals a Radius of 2. Every particle on its point will be 2 and I will go Create and then I am going to do a Runtime before dynamics for my radius, okay, because I want my particles to be increasing over time with their lifespan.
Now this is where I am going to use a smoothstep function. So I am going to go 2+, then I am going to do times 4, times smoothstep, and I want it to happen over the particles lifetime. So from 0, Smoke_particlesShape1.lifespan, age.
And I am going to create that expression right there. So let's see how that one plays. Let's start it running from the beginning. See what our smokes looks like here. So I have got that kind of smoke there. This will hide it as it's born. And my particle shapes don't seem to be changing. Why not? Okay 2+ four times smoothstep, 0, particle_Smoke_ particleShape1.lifespan, particle age. Okay. Edit.
And let's see what my Lifespan per particle is. Ah! This is why they are not changing. I don't have a Lifespan per particle put on there. So now I am going to go into Creation Expression. And my Lifespan per particles, Ctrl+C, Ctrl+V, = random and I am going to have each particle live randomly 20 to 25 for its lifespan.
Somewhere between 20 times 24 frames and 25 times 24 frames. I am going to edit that. Now we should see some results here. Now you can see as the particles live, the radius of the particles get bigger and bigger and bigger. So let's see what our smoke looks like now. So here is our view of our smoke right here, what it looks like, and I can change around and play with all of these parameters that I have made to make my smoke look different. So those are the basic simple parameters of smoke.
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