1 00:00:04,320 --> 00:00:05,670 ‫Hey, welcome back. 2 00:00:05,700 --> 00:00:11,280 ‫In this video, we're going to talk about components and how our base pawn is going to want some of 3 00:00:11,280 --> 00:00:17,490 ‫these components for things like collisions and visual representation, like meshes, as well as a spawn 4 00:00:17,490 --> 00:00:20,740 ‫point from which our projectiles will appear. 5 00:00:20,760 --> 00:00:26,070 ‫We're going to talk about how components, support, attachment so we can attach various components 6 00:00:26,070 --> 00:00:32,760 ‫to each other, as well as how our pawn has a root component which stores the transform information 7 00:00:32,760 --> 00:00:33,930 ‫for the --. 8 00:00:34,200 --> 00:00:40,770 ‫Now we've already created our first C++ class called Base --, and now we're ready to start adding 9 00:00:40,770 --> 00:00:42,630 ‫some things to the base --. 10 00:00:42,690 --> 00:00:50,090 ‫The base -- is going to need some components, such as meshes for the base and turret of the tank. 11 00:00:50,100 --> 00:00:55,470 ‫C In our meshes folder, we have a tank base, we have a tank turret and for the tower we also have 12 00:00:55,470 --> 00:00:57,210 ‫a base and a turret. 13 00:00:57,540 --> 00:01:00,480 ‫So we're going to need a couple of mesh components. 14 00:01:00,480 --> 00:01:06,930 ‫We're also going to want a capsule component to handle collisions so our tank and turret won't be passing 15 00:01:06,930 --> 00:01:08,000 ‫through each other. 16 00:01:08,010 --> 00:01:10,890 ‫Now, let's talk about components for a second. 17 00:01:11,040 --> 00:01:17,180 ‫When we add a component to a class, we need to decide what class that component should be. 18 00:01:17,190 --> 00:01:19,830 ‫Now, one choice is a scene component. 19 00:01:20,070 --> 00:01:26,880 ‫The you seen component class has some properties, such as it has a transform, meaning it has a location, 20 00:01:26,880 --> 00:01:28,380 ‫a rotation and such. 21 00:01:28,440 --> 00:01:30,330 ‫It also supports attachment. 22 00:01:30,330 --> 00:01:34,530 ‫This means we can attach other components to a scene component. 23 00:01:34,530 --> 00:01:36,900 ‫We'll learn more about how that works later. 24 00:01:37,020 --> 00:01:42,780 ‫And a scene component does not have a visual representation, meaning it doesn't have a mesh or anything 25 00:01:42,780 --> 00:01:43,410 ‫like that. 26 00:01:43,410 --> 00:01:45,570 ‫We can't actually see it in the game. 27 00:01:45,570 --> 00:01:51,450 ‫Now there are some other classes in Unreal Engine that are derived from scene component, such as a 28 00:01:51,450 --> 00:01:52,650 ‫capsule component. 29 00:01:52,680 --> 00:01:59,130 ‫The YOU capsule component class is made to handle collision and that's just about all it's good for. 30 00:01:59,130 --> 00:02:05,190 ‫We use the capsule component so that our -- does not fall through the floor or move through walls 31 00:02:05,190 --> 00:02:06,240 ‫and things like that. 32 00:02:06,240 --> 00:02:11,850 ‫Now also derived from the scene component class is the static mesh component. 33 00:02:12,150 --> 00:02:19,110 ‫The use static mesh component class gives us the ability to have a visual representation, specifically 34 00:02:19,140 --> 00:02:25,830 ‫a mesh that will belong to our -- class that we can see in the world as we're moving it around. 35 00:02:26,100 --> 00:02:32,550 ‫Now, by default, our -- class already has a component, it's called root component. 36 00:02:32,550 --> 00:02:37,440 ‫Let's go back into VS code and see if we can find this root component. 37 00:02:37,440 --> 00:02:43,170 ‫So I'm here in Base Pont CP and I'm just going to click anywhere such as here in the constructor and 38 00:02:43,170 --> 00:02:48,270 ‫I'm going to type root component just like that. 39 00:02:48,450 --> 00:02:56,460 ‫Now I'm going to right click on this and click go to definition and all of a sudden we have actor opened 40 00:02:56,460 --> 00:02:56,850 ‫up. 41 00:02:56,850 --> 00:03:04,740 ‫And here in actors in a protected section we see a you seen component pointer called root component. 42 00:03:05,190 --> 00:03:10,470 ‫So this variable called root component exists on the actor class. 43 00:03:10,470 --> 00:03:15,690 ‫So anything derived from actor will inherit this root component variable. 44 00:03:16,260 --> 00:03:20,820 ‫That means our base -- also has this root component variable. 45 00:03:20,850 --> 00:03:27,360 ‫So whenever we think about the location of a particular --, we're actually talking about the location 46 00:03:27,360 --> 00:03:33,870 ‫information stored in the transform of that root component, which is a scene component. 47 00:03:33,870 --> 00:03:36,690 ‫So scene components have their own transform. 48 00:03:36,720 --> 00:03:42,930 ‫I'm going to go ahead and close Actor H and delete this line that I added to the constructor of base 49 00:03:42,930 --> 00:03:43,500 ‫--. 50 00:03:43,890 --> 00:03:50,640 ‫So we know that our -- has this root component and it's type is you seen component, which means our 51 00:03:50,640 --> 00:03:52,770 ‫-- has a transform. 52 00:03:52,770 --> 00:03:57,210 ‫But we also know that this root component does not have a visual representation. 53 00:03:57,210 --> 00:03:58,380 ‫It's invisible. 54 00:03:58,380 --> 00:04:05,820 ‫However, we can reassign that root component with some other object whose type derives from seen component. 55 00:04:05,850 --> 00:04:07,350 ‫Now we saw that the U. 56 00:04:07,350 --> 00:04:10,500 ‫Capsule component class is derived from scene component. 57 00:04:10,500 --> 00:04:17,670 ‫So if we create a capsule, we can assign that to be the root instead of that default scene component. 58 00:04:17,820 --> 00:04:21,360 ‫Now we mentioned that scene components, support attachment. 59 00:04:21,360 --> 00:04:26,790 ‫This means we can create other components and attach them to a scene component. 60 00:04:26,790 --> 00:04:32,730 ‫So if we create a static mesh component, for example, called base mesh, we can attach it to the root 61 00:04:32,730 --> 00:04:33,510 ‫component. 62 00:04:33,540 --> 00:04:40,080 ‫Now, because a static mesh component is derived from the scene component class, it also supports attachment. 63 00:04:40,080 --> 00:04:44,760 ‫So if we create another mesh, we can attach it to the first mesh. 64 00:04:44,760 --> 00:04:50,760 ‫So we could create a current mesh static mesh component and attach it to the base mesh component. 65 00:04:50,790 --> 00:04:53,940 ‫Now we can also just create new scene components. 66 00:04:53,940 --> 00:05:00,690 ‫For example, if we want a scene component that we can call projectile spawn point, we can attach it 67 00:05:00,690 --> 00:05:01,890 ‫to the turret mesh. 68 00:05:01,890 --> 00:05:03,750 ‫Now why would we just create a scene? 69 00:05:03,860 --> 00:05:04,510 ‫Component. 70 00:05:04,520 --> 00:05:07,020 ‫We can't give it its own visual representation. 71 00:05:07,040 --> 00:05:13,280 ‫Well, if we need a spawn point, a location from which we'd like to spawn projectiles, a scene component 72 00:05:13,280 --> 00:05:19,100 ‫is perfect for this because it has its own transform, its own location, rotation, etc. and we can 73 00:05:19,100 --> 00:05:22,460 ‫use that as a point to spawn projectiles from. 74 00:05:22,490 --> 00:05:28,880 ‫So after assigning a capsule to be the root component, our root component will now have the U. 75 00:05:28,910 --> 00:05:36,560 ‫Capsule component class type and the base mesh and the turret mesh would be static mesh components and 76 00:05:36,560 --> 00:05:40,460 ‫our projectile spawn point would be a U seen component. 77 00:05:40,880 --> 00:05:46,340 ‫Now let's talk about this attachment thing for a second, because these things are all attached to each 78 00:05:46,340 --> 00:05:46,670 ‫other. 79 00:05:46,700 --> 00:05:52,850 ‫This means that as the root component moves around in space, everything that's attached to it will 80 00:05:52,850 --> 00:05:54,350 ‫move along with it. 81 00:05:54,740 --> 00:05:59,640 ‫But the base mesh itself can move relative to the root. 82 00:05:59,660 --> 00:06:06,260 ‫For example, it can rotate around and everything attached to the base mesh will follow along. 83 00:06:06,680 --> 00:06:14,210 ‫Likewise, we have this turret mesh attached to the base mesh and it itself can move independently from 84 00:06:14,210 --> 00:06:15,020 ‫the base mesh. 85 00:06:15,050 --> 00:06:21,320 ‫For example, if we rotate the turret mesh, it'll rotate and anything attached to it, such as the 86 00:06:21,320 --> 00:06:25,270 ‫scene component will follow along with the turret mesh. 87 00:06:25,280 --> 00:06:30,560 ‫So the scene component will move around along with the turret mesh as it rotates. 88 00:06:30,560 --> 00:06:35,450 ‫But of course if we wanted to, we could move the scene component relative to the turret mesh. 89 00:06:35,630 --> 00:06:40,550 ‫And since nothing is attached to the scene component, well, there's nothing to follow along with it. 90 00:06:40,580 --> 00:06:46,330 ‫Now let's take a look at how components work in blueprints, what the content folder selected. 91 00:06:46,340 --> 00:06:50,930 ‫I'm going to right click and select Blueprint Class to create a new blueprint. 92 00:06:50,960 --> 00:06:59,000 ‫Let's choose actor and call this Components Actor now double click components actor and notice that 93 00:06:59,000 --> 00:07:01,020 ‫we have default scene root. 94 00:07:01,040 --> 00:07:05,040 ‫This represents that root component variable we saw in C++. 95 00:07:05,060 --> 00:07:11,780 ‫Now, if we want, we can add new components by clicking the add button and selecting the type of component 96 00:07:11,780 --> 00:07:12,770 ‫we'd like to add. 97 00:07:12,770 --> 00:07:15,790 ‫Search for Capsule and Select Capsule Collision. 98 00:07:15,800 --> 00:07:17,900 ‫This is a capsule component. 99 00:07:17,900 --> 00:07:20,320 ‫It's C++ counterpart is the U. 100 00:07:20,330 --> 00:07:21,780 ‫Capsule component class. 101 00:07:21,800 --> 00:07:24,260 ‫Notice it's just under the default scene. 102 00:07:24,260 --> 00:07:27,440 ‫Root This indicates that it's attached to this scene. 103 00:07:27,440 --> 00:07:30,350 ‫Root We can continue adding more components. 104 00:07:30,350 --> 00:07:36,620 ‫For example, if you select Kub, then a static mesh component will be added and it's static mesh property 105 00:07:36,620 --> 00:07:40,430 ‫in the details panel will be automatically set to a cube. 106 00:07:40,430 --> 00:07:41,460 ‫Static mesh. 107 00:07:41,480 --> 00:07:46,420 ‫Now notice in the components panel, the cube is just under the capsule. 108 00:07:46,430 --> 00:07:52,280 ‫If we click the dropdown next to it, we no longer see the cube here so we can collapse this to hide 109 00:07:52,280 --> 00:07:55,490 ‫any objects that are attached to a given component. 110 00:07:55,490 --> 00:08:01,340 ‫Now we can reassign the root component by clicking and dragging one of our components on to the default 111 00:08:01,340 --> 00:08:01,970 ‫scene root. 112 00:08:01,970 --> 00:08:07,370 ‫For example, if I click and drag the capsule on to the default scene root, it now becomes the root 113 00:08:07,370 --> 00:08:08,210 ‫component. 114 00:08:08,210 --> 00:08:11,870 ‫So we've reassigned root component to this capsule component. 115 00:08:11,870 --> 00:08:14,180 ‫We can also assign attachment. 116 00:08:14,180 --> 00:08:16,430 ‫Let's click add and select sphere. 117 00:08:16,430 --> 00:08:21,200 ‫Now by default, the sphere is attached to the capsule just like the cube static mesh. 118 00:08:21,200 --> 00:08:27,560 ‫But if I click and drag sphere on to the cube, the sphere is now attached directly to the cube. 119 00:08:27,560 --> 00:08:33,530 ‫If we click the sphere and drag it on to the capsule, we have the option to either make new root or 120 00:08:33,530 --> 00:08:34,340 ‫attach. 121 00:08:34,700 --> 00:08:39,680 ‫If we select attach, the sphere will just be attached to the capsule again. 122 00:08:39,950 --> 00:08:46,010 ‫But if we were to select make new root, the sphere would become the root component instead. 123 00:08:46,550 --> 00:08:52,910 ‫So we not only have control over creation of new components and how they're attached, but we can also 124 00:08:52,910 --> 00:08:54,770 ‫reassign that root component. 125 00:08:55,130 --> 00:09:00,410 ‫Let's go ahead and select the sphere by left clicking hold shift and left click the cube to select it 126 00:09:00,410 --> 00:09:04,850 ‫as well and hit delete to remove these components. 127 00:09:05,180 --> 00:09:10,520 ‫Now for your challenge, I'd like you to become a little bit more familiar with components in blueprints. 128 00:09:10,520 --> 00:09:12,980 ‫Add a couple of components to our actor. 129 00:09:12,980 --> 00:09:17,510 ‫We already have a capsule component and that's currently the root component. 130 00:09:17,510 --> 00:09:23,960 ‫Add a static mesh component and for its static mesh, assign the tank base, then add a second static 131 00:09:23,960 --> 00:09:27,950 ‫mesh component and assign the tank turret as its static mesh. 132 00:09:27,980 --> 00:09:34,040 ‫Make sure to attach the base mesh to the capsule and attach the turret mesh to the base mesh. 133 00:09:34,040 --> 00:09:40,640 ‫Now once you've done this move and scale the base mesh and observe how the attached turret mesh behaves, 134 00:09:40,640 --> 00:09:42,800 ‫pause the video and give this a try. 135 00:09:45,720 --> 00:09:46,080 ‫Okay. 136 00:09:46,080 --> 00:09:48,780 ‫So I'm going to click Add and select static mesh. 137 00:09:48,780 --> 00:09:53,550 ‫Now in the details panel, I'm going to set the static mesh to the tank base mesh. 138 00:09:53,550 --> 00:09:57,150 ‫Next, I'm going to click Add and select static mesh again. 139 00:09:57,150 --> 00:10:02,760 ‫Notice it's automatically attached to the first static mesh because that's what I still had selected 140 00:10:02,760 --> 00:10:03,840 ‫in the details panel. 141 00:10:03,840 --> 00:10:06,840 ‫I'm going to set the static mesh to the tank turret. 142 00:10:06,870 --> 00:10:12,330 ‫Now with the first static mesh selected, I'm going to move it around and notice that the second static 143 00:10:12,330 --> 00:10:15,330 ‫mesh that's attached to it is moving along with it. 144 00:10:15,330 --> 00:10:18,750 ‫The same works for rotation and scale. 145 00:10:18,750 --> 00:10:22,770 ‫As I scale it up, the attached mesh gets bigger as well. 146 00:10:23,130 --> 00:10:29,400 ‫So we've talked about components and we've seen how we can attach components to other components and 147 00:10:29,400 --> 00:10:30,480 ‫moving and scaling. 148 00:10:30,480 --> 00:10:34,290 ‫One component affects the other components that are attached to it. 149 00:10:34,290 --> 00:10:41,100 ‫We also saw that pons inherit a root component from the actor class and this is the object that stores 150 00:10:41,100 --> 00:10:43,650 ‫the transform information for the pawn. 151 00:10:43,980 --> 00:10:48,270 ‫We'll learn about how to create components in C++ and the lectures to come. 152 00:10:48,840 --> 00:10:50,250 ‫I'll see you in the next video.