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In this lecture, we're going to have a little bit of a play around with prefabs.

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Now, prefabs are a really important concept.

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We haven't got to them yet because we haven't really needed them, but now we're going to start creating

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content for our game.

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It's going to be very important that we know how prefabs work.

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So what are prefabs?

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Prefabs are game objects which we've turned into reusable templates and the original template is called

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the prefab.

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And the copies we add into our scene are called instances, and we'll play around with both of those

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in a moment.

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And turning a game object into a prefab means a lot of things.

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But one important thing it means is we can easily load that prefab into any scene in our game and in

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this particular section of the course we're going to be loading from one scene to the next.

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So it's important that we are able to persist certain things so we can have a player that goes from

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scene one to scene two to scene three, etc., and we need a prefab to be able to do that.

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The challenge throughout this lecture is very simple.

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We won't be saving our work in this lecture, so be sure to have fun experimenting with prefabs as I'm

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explaining them.

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That's the challenge.

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Play around with them.

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If you've already seen prefabs before, it's cool.

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This should be a pretty easy process, but if you haven't seen them before, make sure you're comfortable

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that you understand.

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Oh, that's how prefabs work as I'm experimenting and showing you what's going on.

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So just a reminder, we're not going to be saving our work here.

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It's all just to get a concept.

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In the next lecture, we'll start actually prefab ing things in our game.

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So over in the hierarchy, let's right click and create ourselves something.

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It doesn't really matter what will make a 2D object sprites and we'll do a circle behind all of our

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content.

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So I'm going to drag it over to the left over here.

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Like I said, we're not saving anything, so it's fine for us just to play around with things.

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We've got ourselves a white circle now.

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Up until now, we haven't needed a lot of white circles or things like white circles.

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So all we've been doing is control D to duplicate.

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Now we've got a second white circle.

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Maybe one more.

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Okay, then we've got three circles.

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That's all I wanted to do.

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Easy.

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But what if.

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Here we go.

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What if I clicked on the first one and said, Actually, I want my circles to be bigger and green so

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I go and change the colour to green.

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That looks nice and a little bit bigger.

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So I'm going to scale it up, click on the R tool, scale it up.

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Great.

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Oh, but now I need my other one.

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So what can I do?

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Well, I could delete these.

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Delete, delete and then click on this again.

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Duplicate W move it over.

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Duplicate again.

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There we go.

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Okay, it's all good, but oh, that wasn't quite in the right position.

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It was before.

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Oh, that's a pain.

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Okay, well, if I made a change, then I could go and put that information back onto here.

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So if I change this one to say red, then I could go and click on this one and make it red or orange.

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I guess that turned out to be as well, and so on.

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You get the point.

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It's a real pain, but that's cool.

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It's what we've needed to do up until now.

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So let's talk about prefabs.

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We'll take one of these circles.

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I'll take the original one, I think.

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There we go.

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Circle.

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Now, to turn this into a prefab is really easy.

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All I need to do is grab the circle from my hierarchy, drag it down into my project folder anywhere

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we like.

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And there we go.

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This is now officially a prefab.

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That process of dragging it in there made it prefab.

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You can see now it's blue and it's changed.

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The icon that now is clearly a prefab or it's a prefab game object.

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This is the prefab down here and you can see it's circle dot prefab.

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This has created a brand new thing that is saved on our hard drive.

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So it's just a right click show, an explorer and see in here.

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We've got a whole bunch of things.

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We've got to have folders, animation, scene, sprite, etc. and we've got this circled prefab.

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So that is now something that lives on our hard drive.

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If I was to delete it from here, it would delete from there everything else we put into our scene.

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So if I go to scenes and look at that, you can see we've got our sample scene.

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If I was to go and change something in here.

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So if I was just to add another circle or maybe a, let's see a square and just save it without making

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it a prefab, then the place that is being saved is within our scene, our sample scene that we've got

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at the moment.

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So all of this information is saved in there, which is okay, but not as good.

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We want to be saving our important objects in a separate place so we can use it in many places.

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We can use it from scene to scene.

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I guess that's just the fundamental structure.

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I'm going to get rid of the square fundamental structure of saving it as a prefab.

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Now what can I do?

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I go, go, drag, drag, drag, boom.

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I've got a whole bunch of circles in our scene and you can see it drops them into the hierarchy.

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They're all blue.

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These are all instances.

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So as I mentioned before, these are instances of the prefab.

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The original prefab is not that one there.

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That is now an instance itself.

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It's the original instance, if you will.

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It's the game object that we turn into a prefab.

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But the actual prefab is just here sitting down in the folder, saved as a prefab on our hard drive.

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This is just an instance of that prefab.

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Now say we want to make a change.

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So I get there, I say, Oh, orange.

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What was I thinking?

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What are you thinking, Ricky?

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Crazy.

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No one wants orange nowadays in the video games, they want yellow.

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I changed that one to yellow.

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It doesn't matter which of these instances we change.

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I change circle to group these down here so they're together or else it's going to freak me out a little

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bit.

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There we go.

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They're all nice and together.

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And put that down there just so my OCD is all fine.

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I'm going to have four circles and one of them.

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Let's see this one here.

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Click on it.

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Circle two is yellow.

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What I can do to have all of my circles now become yellow is up in the top right hand corner on the

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inspector you see overrides.

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That's part of the prefab.

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It says prefab open, prefab select and then overrides overrides.

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You can see that there's one change we've made which is part of the Sprite renderer.

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The Sprite renderer is where we change the colour.

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If I click apply all block now all of my instances are yellow.

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It applied back to the prefab and if it's on the prefab then the change propagates out into the instances.

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Now what if I clicked on this and change the scale a little bit?

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So hit ah and scale it up, okay.

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And then go to overrides and apply all they all change on the scale as well.

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There's another way I could do this is by working directly on the prefab.

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So if I double click on the prefab in my folder, that opens up the fresh prefab setting all on its

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own, nothing else to distract us.

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And if I was to make a change within here, say, changed it to green.

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Now you can see the prefab has been changed to green up in the top left.

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A little bit hard to find this one, but in the hierarchy there's a little Chevron Arrow thing next

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to where it says Circle.

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If you click on that, it'll take us back to the scene.

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View.

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We're no longer editing within inside the prefab and you can see it's made the change.

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I don't have to go into that view.

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I could click on the prefab circle and then change the colour to a blue colour and you can see that's

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going to change it all on the fly.

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I like this because then I can see other instances in our seen a change as well.

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At the time that I'm changing the prefab one last place that we can click into the prefab, you see

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this little arrow thing next to my instance.

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If I click on that arrow, I'm now editing the prefab, I'm adding editing this guy down in here.

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And any changes I make to this particular instance is actually this particular prefab.

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So once again, if I go and change the colour to something else, it propagates.

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But this is a nice way of looking at it because I can see them all within context.

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If I double click on here onto the prefab, it's not necessarily going to show me all of those in context.

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I click back out on here, I'm back into the scene and you can tell if you're in the scene or in the

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prefab.

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I'll just click back into the prefab by what you see over here in the hierarchy.

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I don't see anything else, but what I see up at the top here is circle.

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And then if I click back, then you can see now it's showing me I'm on the sample scene.

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It doesn't have that circle on there as it did before.

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Now, one of the important thing I want to show you here is so I go and change one of my instances.

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Circle three, let's go and change circle three to I don't know, we'll make it purple.

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I haven't had that yet.

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Purple.

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That's great.

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And I want that to stay purple.

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But oh you know what?

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I want all of my other instances to be a different colour.

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So now if I go and click on the prefab and change the other instances to more of a red, they changed,

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but the purple one didn't.

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Why is that?

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Well, if you've made a change to the instance, that's different to the prefab.

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When you go and make a change to the prefab, it doesn't override that change that you've just made.

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So I could change the scale, I could change colour.

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I don't have a lot of other things on this particular object at the moment, but any of the components,

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this same logic applies to that.

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By making these changes I've gone and change the scale.

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And from this point on, if I go and change anything on the prefab and the X scale, it's not going

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to change the X scale.

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On my instance that I went and made a modification on that scale.

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However, if I was to go and change the Y scale up like that, they all change on the Y scale because

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I hadn't gone and made a change to the instance.

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Okay, hopefully that makes sense.

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If we change something on the instance then making a change on that same particular thing on the prefab

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is not going to change the instance or roll out and it's a lot easier to see on the light theme than

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it is on the dark theme.

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But any time you've changed something on the instance that's different to the prefab, it bolds the

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particular element.

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So here colour is bolded.

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I know it's hard to see and our x value is bolded as well.

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And if I look at and say, well, I really do believe that the colour is the best colour, but I don't

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actually want to change the scale.

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Then I can go up to overrides and choose a particular thing.

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What was it?

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Yeah, the sprite renderer.

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That's the one I want to apply.

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That's what the prefab has.

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That's what I've got on my instance.

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And I can click, apply and apply that and all of them will be purple.

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But we keep the scaling that they've all got on the particular objects.

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And the other thing to mention in here is that we're dragging these in.

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This is called instantiating our object or instantiating our prefab.

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So here's a prefab, I'm instantiating it.

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That creates an instance we can also instantiate in our code.

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And that's something we'll do later on in this section.

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We'll, we'll say, write some code that says Instantiate a thing and it appears on our screen.

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So that's another good use for prefab.

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So just to summarize then, prefab is a great it allows us to have a lot of objects in our scene, but

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it's all coming from one object.

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So it's an efficient way of creating things.

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It allows us to make changes to one game object on a prefab, for example, change the colour and then

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that will propagate to all the other things in our scene.

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That's an instance of that prefab.

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It allows us to load things from scene to scene.

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If we're on the next level or the next scene, we can easily add new circles to that next scene without

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having to create it from scratch.

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We've got this template that we can work from, so prefabs are really.

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Fundamental aspect of unity, very important.

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And from this point on, we'll be using prefabs a lot more freely.

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So good stuff.

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In this lecture, I hope you had a good chance to experiment, and I'll see you in the next lecture.