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‫Hello and welcome.

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‫In this lecture we're going to be learning about if statements, essentially C++ is branch statements

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‫and we're going to be using it to send our platform backwards and forwards.

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‫Let's dive in.

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‫So there are a couple of places in the comments now where we mentioned that we should do something if

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‫we've gone too far.

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‫How do we do this if.

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‫Well, previously in Blueprint, we did that if with a branch node.

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‫Now in C++ there is a similar concept and it's called an if statement.

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‫So here's a branch node that we had as an example previously, and you can see we had this variable,

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‫it says, I'm hungry, it's a boolean, and we could put it into the condition and then we could have

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‫either a true execution branch or a false execution branch and we could execute code functions.

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‫Anything in Blueprint in C++, it's very similar except it's textual.

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‫So we'd have a variable called I'm Hungry, which is a boolean, and we can just say if and have parentheses

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‫around that.

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‫Then we would open up some curly braces after our if statement often on the next line, and then within

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‫these curly braces we can execute the stuff that should happen if it is true.

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‫So we're saying if I'm hungry, eat junk food while the wife isn't watching and then we can close our

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‫curly braces to say, okay, that's the end of the stuff that should happen conditionally.

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‫And then there's an option that if we wanted to put a false branch, if we wanted to connect something

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‫up to the false here, then we put an else keyword and we can start a second set of braces.

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‫And in here we could do keep playing video games and then we can close the braces.

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‫Now here we can have as many lines as we like between these braces.

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‫It's not necessarily that there's just one single line.

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‫So you could add a lot of code in here if you want to, or you can just have a single line.

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‫And also with the variable in here, it doesn't have to be a variable that plugs into an if statement.

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‫It can be any expression that returns a boolean.

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‫So you can do a little bit of calling a function in here.

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‫You could use an operator to get a different result.

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‫So there's a few different options available to us.

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‫But before any of that, we need to configure how far this platform is allowed to go before it should

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‫turn back.

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‫And to do that, we need a U property.

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‫We've currently got our distance moved as a visible anywhere.

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‫Let's create a new one just above here a you property that should be edit anywhere because we want to

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‫be able to configure it in the editor and I'll use the same category of moving platform from up above

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‫and then down below it.

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‫Here it's going to be a type float because it's going to be a distance and and I'm going to call it

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‫the move distance so we can give it a default value.

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‫I'm going to give it 100 units as the default, but then obviously we can override that, change that

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‫in the editor, and then we can make use of this over in the C++ file.

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‫So the way we're going to do this is we've already got our variable distance moved.

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‫I actually want to not be able to observe that anymore.

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‫So I'm going to remove the visible anywhere property and the distance moved variable from the header

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‫file.

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‫Then I'm going to go back into the C++ and we're going to have to declare it as a local variable instead.

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‫So the easy way to just change that is to stick a float in front of distance move that basically declares

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‫it as a local variable right here inside of tick, which means that we know it's completely fresh each

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‫time we use it.

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‫So now we need to reverse the direction if we've gone too far.

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‫So the way we can do this is we can use less than or equal or equal to or greater than operators that

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‫we've seen in the past as nodes in blueprint.

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‫But now we can use them as operators like we would plus or multiplication.

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‫And the way we can do this is to say, okay, well, we've got the distance moved.

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‫Is this greater than the move distance?

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‫So we can use the greater than symbol, which is this right Chevron.

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‫And then we can put move distance and it looks like I've called it moved distance, but I think it should

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‫be the move distance.

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‫So I've accidentally had an extra D in there.

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‫Let's remove that from the header file and you see this expression here returns a boolean so we can

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‫actually use it inside our if statement.

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‫So what we can do is we can say if space open brackets and then I'm going to cut this expression and

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‫paste it into those brackets.

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‫So it's saying if the distance moved is greater than the move distance, then essentially we want to

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‫reverse the direction.

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‫So that's what we're doing this comment for.

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‫We want to reverse the direction of motion and to reverse the direction of motion.

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‫We've got a platform velocity.

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‫So let's set the platform velocity to the negative of itself, basically reversing its direction.

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‫So platform velocity equals.

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‫Negative platform velocity.

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‫So that's going to basically flip the arrow of the velocity.

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‫I'm going to put a semicolon on the end of that line and let's see if this if statement actually works

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‫as we intend it to.

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‫Let's go over into the editor and hit compile.

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‫And now that that's completed successfully, we can go ahead and hit play and see what happens.

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‫So I'm expecting it to go forward and backwards pretty much as as it's doing, and that's pretty good.

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‫Now, what's actually going on is it's going a little bit past its starting point.

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‫The reason for that.

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‫So if we have a look, that's the starting point.

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‫And if I go and hit play and look to the side from this same angle where my player is standing, you

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‫can see it's going the same distance from the starting point in each direction.

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‫And that's because when we look at what's being calculated here, the distance moved is from a start

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‫location that never changes.

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‫We never update that start location, so we're going in the negative direction.

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‫We're then going to travel past it the same amount as we traveled the other way.

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‫So that's not how I want my platform to work.

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‫So I'm going to challenge you to update your start location.

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‫We're going to be doing that inside the if statement.

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‫So it's only going to happen when we reach the end of our travel and you're going to set it to the current

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‫location so that basically we reset our starting point to the other side and then we can be traveling

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‫in the opposite direction.

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‫So test the results and see if it works as you expect.

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‫Pause video and have a go.

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‫Okay.

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‫Welcome back.

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‫So we're going to after we've reversed the velocity here, it doesn't actually matter whether it's after

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‫or before because they don't have an impact on each other.

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‫We're going to set the start location equal to the current location, which essentially means that in

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‫the next frame the distance moved is going to be zero because we know that the distance between the

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‫start location and itself will be zero.

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‫Let's go back into Unreal, hit the compile button.

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‫And when that's done, let's hit play and see what happens now.

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‫So I expect this to go forwards and backwards.

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‫There you go.

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‫About the same amount of units always going back to its starting location, not going back any further,

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‫which is fantastic.

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‫Just what I wanted to happen.

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‫So that's it for this lecture we've learnt how to use our if statements and Boolean expressions in order

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‫to do that and we've allowed that to send our platform back and forth.

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‫Great stuff.

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‫I'll see you in the next lecture.