 Alright, so let's kick this off by learning a little bit about sine and cosine. So if you're not familiar with this, this will be a great lecture for you because we're going to take a look at why sine and cosine are very important when you're creating patterns, especially a chain link fence pattern like we're creating here. Alright, so let's dive into Houdini and take a look. Alright, so let's get our chain link pattern started by learning a little bit about sine and cosine and how we can use them here inside of Houdini to modify the shape of a line. Okay, so what I'm going to do is drop down a geometry node here. I'm going to call this the chain link generator like so. Cool. And inside of here, what I'm going to do is I'm going to drop down a line and this line is basically going to be the basis for our chain link pattern. Alright, might not seem like it right now, but it will become that here pretty soon. Alright, so what I'm going to do is I'm going to point this guy straight up in y, so I'm going to get rid of all my defaults that I had set up. Alright, so this is basically what we're looking for. And what we need to do is we need to go and add a couple more points so we can actually see the effects of using sine and cosine here. Alright, so what I want to do at this point, now that I have a bunch of points, I'm going to drop down a wrangle node here and we're going to feed in the output of our line into the first input of our attribute wrangle node and we're going to set it so that we run over all the points because what I want to do is for each one of these points, I want to move it in 3D space using sine and cosine. Alright, and sine and cosine basically are the components that allow you to build a circle with all these points, to just put it plainly. If you combine sine and cosine together, what you can do is you can build a circle out of a line. Alright, so the way it works is if you come in here and we say at p.x, alright, because I'm going to just worry about just the cosine currently. So let's hit 3 on the keyboard and go to the front viewport. So what I want to say is that, let me actually turn the line back on here so we have something to look at here. Cool. What I want to do is I want to say that our x position, currently our x position is zero right now on each of these points, alright. I want to say that our x position is equal to let's say the cosine of our y position for each one of those points. Alright, so let's take a look at that. And look at that, we get some sort of curve here, alright. It's really just one portion of a circle. Alright, so what we're doing is we're literally taking in our current y position and just feeding it into the cosine function here. So if we come back up to our line before we modified it, all these values or the y value for each one of these points goes from zero all the way up to one. Because our line has a length of one. Alright, so this point zero is the value of zero. And we could actually visualize what the y value is over here. Alright, if we put in some sort of attribute. So if I say something like f at y val, alright, so we're creating our own attribute on our points here. Is equal to at p dot y and that's the y position of each point. So if we come down here now into the geometry spreadsheet, you can see that each one of those points now has a y value. So what we're doing is we're feeding in that value into that cosine value. Alright, super cool. Alright, so let's take a look at some more useful techniques here. So if I were to, let's say, multiply this, let's say times two. And we need to put in the two. There we go. We increase that curve. Now it's starting to look like some sort of function graph or something like that. Alright, and at this point, that's not exactly what I'm looking for. I want to create some sort of smooth ramped curve. Okay, and so to do that, I need to come in here and say dollar pi. All right, that's a global variable for the value pi or 3.14. And I want to multiply that by two times our at p dot y. And look at that. We now get the full circle, all right? Cuz pi times two basically is 360 degrees. All right, but this will give us 6.2 in ratings. But you convert that to degrees, we'll get 360 degrees. And then we're basically just mapping that based off the y position of each point. All right, so hopefully that makes it, let me know if that. All right, so now we've got that value going. Let's go back to our perspective view and hit one on the keyboard. And you can see that it looks like it's spiraling around. If we were coming into that front view again, it looks like it's kind of spiraling around. Well, we could actually create a full circle out of this. We can go and say at p dot z is equal to the sign of that same value. So pi times two or 360 degrees and take our at p dot y value. And look at that, we now have a perfect spiral, perfect circle. So if we were to remove all of our y value from here now, we'll actually need a wrangle value down here. And we're gonna say at p dot y equals zero. Look at that, perfect circle. All right, so hopefully that helps clear things up a little bit for sign and cosign, very powerful stuff. And we're gonna use it to create our chain pattern. So I'm gonna close out the lecture there. And in the next lecture, we are going to get our pattern going. Thanks much.