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‫Hello and welcome.

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‫In this lecture, we're going to be learning about something called the world object, a very important

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‫object in Unreal.

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‫I'm going to see how we can get the current time in our game from this object and print it out to the

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‫console by the end of this lecture.

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‫So let's dive in and see how this works.

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‫So to be able to do line tracers or sweeps, we need to understand another concept, another type of

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‫object that exists in unreal land, and that object is the world.

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‫So we've dealt a lot with levels.

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‫So if we go to our content draw, we've dealt with maps as well.

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‫So the map and level we've kind of talked about as being synonymous.

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‫However, a world is kind of there in the beginning.

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‫In the beginning was the new world and the new world is the type, is the class for basically the environment

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‫that we're seeing when we play a game.

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‫But it's not just necessarily one level.

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‫You can load a level which is called a you level in C++, which is just a collection of the actors that

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‫we should bring into the new world.

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‫So you can load a level into your world, but not just necessarily one level.

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‫You may load in multiple levels into a single world.

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‫And that's because often we have these streaming levels, we have very large levels where we don't want

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‫to load everything, every actor into the level in one go for performance reasons.

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‫So we split it up into multiple levels and that allows us to bring in only parts of the scene as they're

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‫required.

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‫So if we have a look at the documentation page on New World, I think it describes it rather succinctly

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‫that the world is the top level object representing a map or a sandbox in which actors and components

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‫will exist and be rendered.

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‫And if you look a little bit further down, it says that the world can be a single persistent level,

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‫basically meaning a level that will constantly be there or with potentially an optional list of streaming

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‫levels or basically levels that can be loaded whenever we want.

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‫Now, why is any of this interesting?

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‫It's interesting because it allows us to do line tracing.

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‫If we search the documentation here for line trace, then you will see that there's a bunch of functionality

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‫here, particularly the one that's most interesting to us is the line trace single by channel or the

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‫line trace multi by channel, which essentially allows us respectively to get hold of that first object

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‫hit or all of the objects hit by a line trace.

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‫And you can see that the list of arguments, especially if I look at the line trace single, the list

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‫of arguments has the start, it has the end, it has a trace channel for which to do the trace.

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‫And it actually gives us a result in the parameter list, which is a little bit strange and we will

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‫be covering that shortly.

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‫But anyway, this is the line trace.

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‫We also have the ability to do a sweep.

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‫So if we search for sweep, you can see there is a sweep multi bi channel.

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‫There's also a sweep single by channel.

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‫And here as well as the start and end, you also have a collision f collision shape type that you can

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‫pass in.

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‫Basically if we click on that F collision shape, you can follow through in the documentation in Unreal

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‫to read more about it and you can see that F collision shape basically supports being either a sphere

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‫capsule box or a line.

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‫So we're going to be using the sphere in our case like so and we'll see how to construct these later

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‫on.

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‫But you can see why we want to get hold of that new world, why it's important to us.

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‫But the question is how do we get hold of the new world?

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‫And once we've got hold of it, how do we use it?

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‫Well, let's go and have a look in Visual Studio code.

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‫On every component and every actor, there is a function called Get World.

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‫And if you type get world and then parentheses, this returns an object of type U world.

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‫In fact, a pointer to an object of type new world.

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‫So let's store that.

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‫We've got a New World pointer, which is going to be we'll just call it the world, shall we?

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‫And that's equal to get world.

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‫And then we can put a semicolon at the end there.

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‫Now, in order to actually get hold of anything from this world, we're going to use the arrow operator.

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‫So we're going to do World Arrow, and then we would be able to go and have a look at some of the details

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‫of that world.

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‫But before we do that, we need to include its header file because otherwise this C++ file, when the

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‫compiler gets to it, isn't going to know what is included inside a new world type.

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‫It has no information about a new world whatsoever.

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‫So to fix that, we need to look at our documentation for New World.

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‫Scroll to the top and look for that place where it.

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‫Says include and that gives us the include we need to use you can see include quote engine Ford slash

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‫world that's what we need so we'll just put that after I grab a H here and now if we hit control space,

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‫we should get a list of the things that we can do with this particular world.

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‫And there's many of them we've got.

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‫Obviously, we can find our line trace, we can find our sweep by multi or single.

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‫So I'd like to challenge you to print the time lapse.

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‫This is a property available on the New World object.

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‫You're going to find the time seconds property read up about it in the documentation which is linked

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‫against this lecture and store it in a variable of the appropriate type.

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‫Again, looking at the documentation will tell you what the type should be and then log that to the

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‫console again using the appropriate format.

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‫Specify a pause video and have a go.

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‫Okay welcome back.

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‫So we're going to make use of this in and the if I searched through for time in the new world documentation

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‫you can see there is a float called time seconds.

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‫That's the one that I want in this case is this is the game time.

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‫So if you slow down or speed up time, this gets slowed down or sped up as well.

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‫But there are ones where that doesn't get affected.

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‫There's different ones.

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‫You've got the time, seconds, the unpause time, seconds.

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‫There's also the real time seconds, which doesn't get paused or changed in any way.

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‫So I'm interested in the time seconds.

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‫It doesn't really matter which one we use because they're all floats anyway.

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‫So I'm going to create a float called Time and store the World Arrow Time.

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‫Seconds in there now for short, we don't actually need to put the world into its own variable.

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‫It's quite short enough to just call get world.

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‫So that's what we typically do.

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‫Will do get world then arrow time seconds like.

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‫So now we can do a log which we're going to say the current time is and then we're going to do a percent

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‫F because we are printing out a floating point number here and then we can give it the time as the inputs

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‫into the log.

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‫Now let's go control alt f 11 to live code and then we're going to open up and dock the output log.

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‫And hit play.

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‫And there you can see that we've got a current time which is counting up in seconds as the time elapses

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‫in our game like so.

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‫And if we actually hit the pause button, you notice that the time stops going and if we hit play it

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‫just resumes from where we were.

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‫He wants to.

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‫You could experiment with using the real time seconds and see whether that effect happens.

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‫But I'm not going to here.

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‫We've shown that we can get hold of this new world objects, this world object that we are currently

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‫in and that we can get properties from it using our arrow.

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‫Operator Pat yourself on the back and I'll see you in the next lecture.