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In this lecture, we're going to use the add torque method to rotate our player.

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And we're going to talk a little bit about linear drag and angular drag.

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So let's get started.

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We need to jump into our assets directory.

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Right click, create ourselves a new folder which we will call scripts, double click into that and

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then right click create a C-sharp script, which we will call player controller.

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Now let's just have a look at what we need to do here.

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Here's Barry clicked at the game object.

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Sorry, the parent game object level.

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If I click on a then I can rotate variance.

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What I want to do, I want to be rotating.

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And you can see I mentioned before that it's rotating around the inner pivot point.

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We can finesse that later on.

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If you want to feel like he's spinning more around his knees or his feet, then we can do that.

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But at the moment he's kind of spinning in the middle and that's okay for the moment.

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So you can see we want to apply this.

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And in the past what we've played around with is just changing the transform rotation.

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So just say make the rotation higher or lower on the Z axis or positive or negative, and that will

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have it move around.

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But that's a little bit clumsy because if we're saying, hey, move the rotation, move the transform

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rotation, but he's touching the world, we can have weird artifacts where it doesn't quite work properly.

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We've got the physics engine not playing nicely with us, just directly manipulating our game object

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like this.

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So I'm going to pop that back to zero.

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Sorry for spinning you around, Barry.

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What we need to do instead is apply a force.

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So to use Unity's physics engine to apply a force and the force that is used for rotation is called

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torque.

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So that's the name of the sort of force that will have our guys spin around.

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So let's open up our player controller script.

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And in here we're going to add some talk to the character when the player pushes a key on the keyboard.

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And the very first thing we need to think about is what is the torque being applied to?

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Well, just back into unity again, I know I've nearly jumped into this script, but back into here,

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we're applying the talk to the rigid body.

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Rigid bodies are the things that make objects move and respond to physics in unity.

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So first of all, we need to tap into this rigid body component.

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And the way we do that within our start method in here, we're going to use our jet component.

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If you're a jet component and we're going to get what sort of component, it'll be the rigid body,

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make sure it's 2D and then our parentheses and semicolon.

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So we're getting that, but getting it doesn't do much.

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We need to store it in a variable so we can use it in another place.

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So we will add a little space in here and we will store it in something called r b, so rigid body two

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D and then equals.

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And this is going to our red squiggly line because it's saying we haven't actually defined this as a

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variable yet.

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Now what I could do in START is to say, what is this?

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This is of type rigid body 2D and I could declare my variable in the start method just here.

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And our variable is called rigid body 2d.

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However, I'm wanting to use this in update because in update I want to say if you push left, make

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the rigid body apply torque in a left direction, if you push the right, apply in the right direction.

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So if I start to type R by 2D in here, you can see we've got our red squiggly line.

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And why is that?

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Well, we're going to talk about this a lot more throughout this course, but this is a first taste

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of the fact that certain things can be used in certain areas and not in others.

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And it's a way for us to protect our code.

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So here I can I can define a variable.

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And if it's between these curly braces within the start method, that means I can only ever use this

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and call this and modify this within my start method so it's local to within these curly braces.

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And so when I try to use it down here within a totally different method, it's saying I don't know what

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that is, doesn't exist in the current context.

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So what we're doing within START is we are encapsulating this variable, so it only lives within the

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START method.

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So what do we do in this instance?

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Well, you can see these curly prices up here, top and bottom.

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This relates to all of the content contained within our class.

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So if we want to make a class variable variable or a member variable, we could call it.

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And up at the very top of our class we can say rigid body to DX and then we will call it RB to DX and

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then semicolon and it's going to want to autocomplete semicolon.

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I'm going to get rid of this one.

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I've got down in update because we don't need it down there.

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And you can see we don't have a squiggly line there and we don't have a squiggly line here.

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And then I'm going to remove the type in front of my AB 2d because I don't need to define the type again.

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I'm just saying I already know what the variable is.

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The variable has been declared up to the top of our class and now I can use this anywhere in our class.

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I can use it within update.

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I can use it within a new method I create because it's a member variable and it is available to any

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of our methods within this class.

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So hopefully that explains a little bit of why we put some variables here, why we put some variables

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there.

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If you only need to use it within a method, there's no need to have it as a member variable.

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But if you want to have it accessible in many places, then you do need to have it as a member variable

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so that it is available anywhere within our class.

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In update, let's create ourselves and if statement if what are we doing in here?

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I'm going to use the old input system just because it's really quick and really easy.

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I promise you we will use the new input system at some point throughout this course.

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But all we need to say in here is if input dot get key and that's the method get key.

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So we're just using the input class and we're saying within there get key.

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We're trying to find if you've pushed a certain key on the keyboard and in parentheses here we need

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to say which key we're interested in.

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I'm going to say key code.

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We're looking for the left arrow.

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I think we'll do here.

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First of all, so left arrow.

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So this is a way of saying if we push the left key, then what do we want to do in here?

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Well, this is where we need to apply our ad talk.

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So what do we need to do?

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First of all, we need to access the rigid body two D So what should we start with here?

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Rigid body two D That means we're accessing Barry's rigid body to D dot and we can use the method in

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here ad talk.

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You can see right up here near the top, add talk and then you can see in the signature in here it's

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looking for parameter.

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Remember, parameters go within the parentheses, it's looking for a value that is a float and that

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value is going to be the amount of talk we want to apply.

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So we can add a value of, say, one in here, for example, and then put our semicolon.

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Now it's pretty bad to have a magic number that's buried within our code.

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So instead of doing one in here, let's create ourselves another member variable.

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Remember, member variable variable can be used anywhere in our code, right up at the top here above

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rigid body to DX that will be a serialized field and b of type.

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What what sort of type is this variable we're making?

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It will be a float.

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Very good.

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And we'll call this talk amount and then we'll initialize that at, I don't know, initialize it at

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one just to give it a value, a starting value else, or else it will initialize at zero.

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So instead of one in here, we'll type in talk amount and there we go.

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We've created a way for us to apply torque, which is a force that rotates whenever we push the left

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over arrow.

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So I'm going to save that back over into unity.

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There's one step we need to do for this to work.

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Do you know what step that is?

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We need to add our player controller to Barre Sung and a scroll down.

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I'm going to drag my player controller script where we get the blue line just there.

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Excellent.

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And now when I click on play, if I hit the left arrow, then we should see some sort of torque being

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applied.

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None yet it might be that.

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There we go.

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It was just that he was going down the hill and the amount of torque wasn't strong enough to counteract

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the physics through gravity.

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So I'll put the talk amount up to ten.

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We'll see how that goes.

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I have a feeling he's just going to go flip de flip.

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Yep.

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Whoa.

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There he.

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Okay, well, that could be a game right there, but we've successfully applied torque.

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When you push left on the left arrow, there's a lot of settings for us to tweak in here.

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And let's put this back to three for now, I think I'm not exactly sure what we want in there, but

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we're not yet at the stage where we want to tune it just yet.

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But I've got a challenge for you at this stage.

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The challenge is to finish our rotation when the player pushes the right arrow, make the character

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rotate in the other direction.

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So there you go.

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A quick little challenge.

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Pause the video.

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Take that on now.

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Okay.

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So this one's pretty straightforward.

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I'm going to copy my if statement that we've already put in there.

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Pop that down below.

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I'm going to change from left arrow to right arrow.

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And instead of torque amount, this is the one tricky bit in the whole area.

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Did you figure this out?

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We're going to add negative torque amount.

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We're going to have it go in the other direction.

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You could have gone and said float talk about is this and you know rotate one direction is this the

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other direction is that particularly if you want him to do a front flip quicker than a back flip, but

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I want it to be the same.

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I don't mind that it's going to say negative torque amount.

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What I'm also going to do in here, we've got two if statements.

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So if you're doing this, great.

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If you're doing that, what happens if you're pushing both of the arrows?

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That's going to be a bit of a conflict.

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So let's do something that says you can't do that.

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And the way we're going to do that is to add an else.

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If so, if you're pushing this, do that else.

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If so, in other words, if you're not already pushing this first if statement the first left key,

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that's what else means ls means otherwise.

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Then if you're pushing the right arrow, do this.

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That just is a way for us to make sure we're not accidentally doing both arrows at the same time and

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getting some weird sort of conflict.

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So I'm going to save click on play.

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We'll see what happens here.

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When I push left, arrow goes rotate, the left right arrow rotates to the right.

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Excellent.

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Although if I push left arrow and then let go, ooh, he's doing lots and lots of spinning.

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So let's look at that briefly what's going on here?

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If you look at Barre's rigid body, you'll see we've got a couple of values in here.

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Mass linear drag, angular drag and gravity scale.

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Now, the angular drag is going to relate to how much friction there is when we spin around and the

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linear drag is the same information when we're going forwards and backwards.

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So I have a little micro challenge for you here.

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Tune the linear drag and angular drag of your character until it feels good, until it's not just spinning

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out of control and getting into the death spin, I call it.

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So you can see here, if I just hold down lift and get him spinning.

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Okay, that's a little bit too quick for a snowboarder.

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I think so.

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Let's not have the death spin and let's have it that when you let go, he doesn't just keep spinning

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and spinning and spinning like that.

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So pause the video and play around with the tuning values of the linear drag and the angular drag and

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see how you go.

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Okay.

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Welcome back.

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Now, there's a really tricky thing going in here.

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Our angular drag and our torque amount or the speed we're trying to make it turn.

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Those two relate together.

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So I'm going to start with my talk amount at say, eight, and then I'm going to jump up to my angular

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drag and make that 15.

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Now, how do I know those are the numbers?

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Will I just put them in and play around with it and play around with it and just to see how it went?

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They're not perfect, but they're are they're better than they were before.

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And my linear drag I'm going to put at 0.5 for now, but that one will need to be balanced in conjunction

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with our level sprite shape, speed on the effect.

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So if the speed is ten, if we put this to say 20 back over onto Barre, if we put the linear drag at

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a higher amount, those two are going to relate.

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So if you have a much higher linear drag, you might need to have a higher speed on your effective.

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But let's see how my tuning values are going now.

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I've got those things set up.

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I'm going down the hill.

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Not too bad.

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That speeds a little bit too slow.

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But I'm not getting into the death spin.

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I'm spinning at a fairly consistent amount, which is what I like.

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I just don't want it to speed up or slow down.

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I want it to be just a nice, steady, consistent spin.

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Okay, so I think I need to make him spin a little bit quicker.

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So I'm going to put this up to ten and see if that's just a little bit nicer.

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When it comes to spinning and not super out of control looks pretty quick.

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Go up the hill.

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That's pretty good.

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That's roughly what I'm looking for here with my spin.

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So there we go.

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We've got some general values.

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We're in the ballpark.

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And you've learned a little bit about the angular drag and linear drag and the torque amount we've set

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ourselves up so that we're using the add torque method to spin around our snowboarder.

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Great stuff.

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I'll see you in the next lecture.