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Boids is a whole field of animal behavioral studies and it's just a fascinating thing that Blender is able to simulate, it's able to simulate the intelligent behavior of these particles. Each of the dots that you see on your screen is an actual particle and those particles are being drawn by this sphere that's running around there. And the particles interact with each other. So you have swarms of insects, you have schools of fish, you have herds of buffaloes, and in this case you have seagulls flocking around the boat here at the harbor.
So how do we set up boids? Well, let's go and break it down and I'll walk you through it. First of all, you need a base from which the birds will start, and so here we have this cube, and we've just gone ahead and assigned a new physic system, and instead of Newtonian, we've clicked on Boids. When we click Boids then we have a set of controls here on this panel. And what this is, is a bunch of rules as to each particle as it flies around or swims around or whatever.
What behavior takes presence over other behaviors? So here is the behaviors that you have. Let's say you're walking down on a crowded street. First of all, you have the desire to stay with the crowd, but avoid colliding in to other people. You have a certain goal that you are trying to get towards, but you have to navigate through this maze of people. So a lot of swarms have a center, and and people want to gravitate towards the center, and then we have some velocities involved. That you don't want to go too much faster than the guy next to you.
Those kind of behaviors you can rank and rate here and just by clicking the Move Up or Move Down, you can move that rule up or down in precedence. And then set the overall general rating of that rule, relative to all the other rules. Boids works in three-dimensions. As we walk around we can see that this is actually a three-dimensional flock. We can make it a lot simpler by clicking only 2D and now the birds will only operate and swarm around in two-dimensions, and not actually fly up into the Z direction.
We can control how fast the birds change direction and change speed here by limiting or changing the Maximum Velocity. Here we have set it at 10 units and the Average Velocity is much less than that. So that's means that they can really speed up and take a couple of wing beats and really get fast. Laterally as well as tangentially how fast they can bank to stay together in the flock, and flocks can actually -- if you try to scatter them, if the guiding force changes too fast, then they will actually fly off and get lost and not become part of the flock anymore.
The Visualization settings are pretty much the same. You can draw them as whatever and in this case, what I have done is I have created the shape called a Bird. It's just a very simple mesh shape. We can probably click it over here. Just select it and I can press C to-- oops, I'm going to press Ctrl+S to take my cursor to it and then press C to center in and now I can just zoom right in here. And all I have done is I just sculpted a simple little mesh shape that looks like a little dove flying around.
And what happens then is for every particle then, Blender takes that mesh shape and makes a bird out of it. And then the bird orients itself in the direction in whichever the particle is going. Coming back to the Particle System now, each bird starts at a certain time. In this case a flock when it first takes off it needs time to coalesce, if you will, and it just kind of weird thing to watch. But when they are all sitting there on the ground, they all kind of take off and then they all kind of like figure out who is the leader and where we are going and all that kind of good stuff.
That takes about a second or so to do. So I have started the actual simulation at -30, so that by the time we get to frame 1, the flock is all up in the air, and everybody is swarming around, and they have all kind of figured out who the leader is. Each of the birds is going to last for 1500 frames, which is well in excess of the duration of the simulation, and finally I wanted them randomly emitted from this cube, so as if the birds were all just kind of like sitting around on the patio and all of a sudden they just all wanted to take off.
You are going to have birds, smaller than other birds as well, and then you can combine this little reactor system so that when the birds fly into the barn and then inside the barn is reactor system then even more birds fly out. So how do we guide these birds? And the answer is right here in this object, which I have set up as a force field. And I have set this ball, just a simple ball, and I have assigned it to be a force field and it's the same kind of field that we've talked about with all the other particle systems.
Only I gave it a really strong strength, so that it really can draw these birds from the pretty far distance away. They'll all be drawn towards it. Then all I needed to do was just move this around and to do that moving around, I used all of our basic animation techniques to go ahead and move the cube and key different locations showing down here in the IPO window as to where this cube moves around. So as it moves, it draws the birds and you can kind of see as it's moving away, see how these birds are kind of drawn towards it.
And the ones out here going, "hey, I'm getting away from the flock," and so those boids rules come into play. They turn around and they kind of fly faster to try to catch up to the center mass of the flock. And then just about the time that these birds start to overshoot this sphere, this sphere moves so that they can now bank around, and follow around and swarm around just the same way I have seen birds do. You know when they are getting ready to go south for the winter.
We can see now that they start going around, and they will eventually circle around this sphere. So that's how you can add birds and boids. You'll see them all over in different simulations now that you know what to look for. Feel free to experiment. There is a lot of research papers on what makes up a swarm and how is it controlled, but this is how you can do it in Blender.
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